Final Exam

This final exam is due on May 6th. Please email it to be at mark.mcginley@ttu.edu.

Each of these questions is worth 20 points. I expect that it should be possible to provide an excellant answer to each of these questins in less than two pages double spaced (per question). You may use the Ecology Reader, any notes you have, or any other source of information to help you prepare this exam (besides another class member). Please let me know if you have any questions.

Question 1. (20 points)

How would you respond if one of your student's parents asked you "Why should my students learn about evolution"?

Question 2. (20 points)

Why is exponential growth an unrealistic pattern for most species?

Question 3. (20 points)

List the major interspecific interactions that occur in a community? discuss the role that these interactions can occur in influencing population and community characteristics.

Question 4. (20 points)

Define natural selection. Why is this process important to biologists?

Question 5. (20 points)

Define, compare and contrast energy flow and nutrient cycling. (because of the difficulty in putting diagrams in Microsoft Word, you should be able to answer this question without using diagrams).

Final Assignment

I am afraid that I am badly overscheduled this semester and that combined with being sick for a while has caused me to be unexcusably far behind. I realized that I failed to write down the due date of your writing assignment in my schedule so you think that you have an assignment due soon that has not yet been assigned. I apologize for the inconveience.

First, the writing assignment due on the 25th is cancelled.

Second, your final exam for the course will be due on May 6th *not May 2nd as it says on the syllabus)

Third, becasue of the lack of writing assignment, your grades will be calculated as follows. I will calculate grades three ways and you will earn the highest grade.

Midterm Exam 30%
Cumulative Final Exam 70%

or

Midterm Exam 60%
Cumulative Final Exam 40%

or

Midterm Exam 50%
Cumulative Final Exam 50%

Evidence for Evolution

I think that it is important to be able to explain to students that scientists do not support evolution because they are anti-religious but rather because the theory of evolution helps us to understand every facet of biology. Here is a link to a powerpoint presentation that outlines some of the strongest lines of evidence in support of evolution.

http://www.slideshare.net/secret/yZbDE8FNSCzKFS

How I Introduce Evolution to My Students at Tech

My training is in ecology, with a emphasis in the field of evolutionary ecology, so it is really not possible for me to talk about biology without using an evolutionary framework. As you might be remember, I started out this class by talking about “natural selection”- microevolution.

I have no idea what the exact figures are, but I know that the majority of my students come to Tech not-believing in evolution because of what they have learned from the pastors and parents while growing up.

When I teach evolution, I am simply trying to teach students the background theory that will help them make sense of the biological world. In the same way that I thought that understanding how scientists use mathematical models such as the Lotka-volterra model of competition to understand communities, I think that it is imperative that students studying biology have a strong foundation in evolutionary theory. Thus, I am not trying to “convert” anyone or to challenge their religious beliefs. I do however find it interesting that I am more likely to challenge people’s religious beliefs when talking about evolution than I am when talking about competition models. We should spend some time talking about why that is.

I always start by talking about science. Science is a way of learning about the world. Other ways of learning about the world include philosophy and religion.

Science is differentiated from alternative ways of learning about the world by
1) what it studies
2) how it studies it

(a) Science deals with the natural world and assumes that the world is governed by “natural laws” (I don’t spend too much time worrying about where these laws came from, I just accept that they exist)and (b) science only studies things that can be observed

Religion, on the other hane deals with the supernatural so science simply can’t study it.

Scientists learn about the world using the scientific method. Scientists use observations and experiments to test predictions of hypotheses. Thus, data determines “truth” in science. Religious truth often relies on “revelations” not data.

Thus, science and religion differ on what they can study and how they study it.
Here is the critical question- which way of learning about the world is best? Any particular method is not the best, they are complementary ways of learning about the world and each works best within its intended boundaries. Science has nothing to say about religion, faith, or God.

My suggestion is that if you want to study observable phenomena that take place in the natural world then science is the best approach. We spend our lives surrounded by the applied knowledge that comes from using the process of science.

Think about a couple of examples

1) you come out in the morning and you can’t start your car.

Possible hypotheses
- you left your lights on and the battery has gone dead
- something is wrong with the starter

Where do these hypotheses come from? The knowledge that engines run according the laws of physics and chemistry helps us to understand how they work

Alternative hypotheses
-you ran over a fairy on the way home last night and they are punishing you
-your neighbor is a witch and has put a hex on your car because your dog barks too much

We are likely to laugh at these alternative hypotheses because we understand the mechanical basis of car problems. Who do you take your car to for repairs- (i) Gus the mechanic (who whether he knows it or not uses his knowledge of physics and chemistry to diagnose what is wrong and repair your car) or (ii) Princess Fatima the Gypsy around the corner? Obviously, we choose Gus.

2) What do you do if you get sick?

The most obvious answer is that you go to the Doctor and do what they tell you. Certainly you might ask people to pray for you or pray for yourself. Some religions (e.g., Christian Scientists) rely on spiritual healing alone and will not take their children to the doctor when they are sick. I doubt that most people around here would support that position.

Here is a great quote from Einstein- “The whole of science is nothing more than a refinement of everyday thinking.”

In my introductory Biology class I discuss the evolution of plants. Never have I had a student have problems with green algae giving rise to mosses, mosses evolving into ferns etc. The problem arises when we start talking about human origins. Humans descended from apes- monkeys are ancestors.


Why this is is difficult for me to understand- it appears that we are in the middle of a culture war. From an exhibit in the Institute of Creation Research Museum we learn that (i) Creationism gives us True Faith, True Morality, True Hope, True Americanism, True Family Life and (ii) Evolutionism gives us Communism, Naziism, Atheism, Slavery, Racism, Pornography, Genocide, Abortion, Infanticide , Homosexuality, Child Abuse, Bestiality. This goes back to William Jennings Bryan’s ideas of evolution causing a loss of morals. I don't understand this point of view, but clearly this is the way that many people think which is why they are willing to fight so hard to get creation in and evolution out.

I think that students should be encouraged to think about how they use the different ways of learning about the world. When do they use science, when do they use religion? What do they do when the two are in conflict? How do they justify using science to study the world expect for when it conflicts with their religious beliefs (why doesn’t science work then?). Each person needs to draw their own conclusion about these issues. However, I think that it is extremely important that we not allow people to push their “religious agendas” into the science classroom.

Creationism and Intelligent Design

We are now reaching what is usually the most difficult part of this course- talking about evolution. Because Lubbock is located near the buckle of the Bible Belt, this topic is always controversial with my students here at Tech (including past Multidisplinary Science Masters Degree students). If we were meeting in a face to face setting then you would hopefully know me well enough to conclude that I am not an evil person (and if you concluded that I was evil, it would be for a better reason than believing in evolution). Obviously, the teaching of evolution in Texas schools continues to be controversial and it remains to be seen what the revised TEKS will be like. Because my understanding of the process of evolution is the most powerful tool that I have in my biological toolbag I think it is critical that you learn why I think that evolution is such a powerful tool for helping us to learn about biology. My goal is not to be controversial or step on anyone's toes and I hope that we will be able to have good discussions about this topic.

Creationism and Intelligent Design

In his book “Tower of Babel The Evidence Against the New Creationism”, Robert Pennock reviews the various types of Creationists.

“Wild-type” Creationist

God dictated the bible word for word so we must take it literally. From Genesis we know (i)God created the world from nothing in 6 days, 6000 years ago and (ii) God destroyed the world with a great flood, all current people and animals are descendents of Noah’s Arc.

There are different views of Creationism today which arises out of biblical interpretation

Most creationists consider themselves as Evangelicals
- Biblical inerrancy- can be understood in different ways
- Bible is the revealed word of God- so every word is true
- plenary verbal inspiration- Biblical writers directed by God but used own style
- inspired concepts- written down by people over time

Young Earth Creationism

Bible is meant to be taken literally on all matters of faith and the real world

-creation took 6 24 hour days
-Adam formed directly from the dust on the ground and Eve from Adam’s rib
- Jonah was literally swallowed and lived in the Belly by as great fish

1- sudden creation of the universe, energy, and life out of nothing
2- the insufficiency of mutation and natural selection in bringing about the development of all living kinds from a single organism
3- changes only within fixed limits of originally created species
4- separate ancestry of humans and apes
5- explanation of earths geology by catastrophism including a worldwide flood
6- A relatively recent inception of earth and living kinds

Dated by readings of ancestry in the Bible- 6000 to 10,000 years

Young Earth Creationists include-
1)Institute for Creation Research- San Diego - Duane Gish, Henry Morris and his son
2)Answers in Geneis- Kentucky-Ken Ham and Gary Parker
3)Center for Scientific Creationism- Phoenix

Old Earth Creationism

-still consider biblical inerrancy, just don’t read the bible literally

Days are not 24 hour human days, but are God-sized days
Others apply gap interpretation- gaps between Genesis 1:1 and 1:2
Days are “actual days” but they are not consecutive

There is a big battle between the Young Earth Creationists and the Old Earth Creationists

Progressive Creationism

Accepts much of the scientific picture of development of the universe, assuming for the most part that it developed according to natural laws.
- God intervened at strategic points along the way

Theistic Evolutionism

Theists who accept Darwinian evolution. Basically view God as a creator- started physical laws etc.

Evolutionary creationism

God directly guided the process of evolution

Intelligent-Design Creationism

Many ID proponents hold advanced degrees and positions in universities

Phillip Johnson- UC Berkely Law school
Michael Behe- Biochemist,Lehigh University Biology Department

Johnson’s view
1. personal creator
2. supernatural
3. initiated
4. continues to control the process of creation
5. in the furtherance of some end or purpose

“irreducible complexity”- some systems are complex and can only work if the entire system is in place
-therefore there is no way that they could be formed by gradual steps because there is no way that earlier versions could have been selected for

Interesting idea, but again I don’t see that it is science (even worse it doesn’t help us get anywhere- can’t make any predictions or lead to new avenues of study)

Is there a controversy between evolution and creationism?

1) Scientific controversy?

No- evolution remains the cornerstone upon which everything in biology makes sense. No “real biologist” that I know thinks that there is a problem. I know of no creation scientists or ID proponents that do not admit to being Christian and that that is a important part of why they feel as they do (I at least respect that most of these ID scientist are up front about their religious beliefs)

Theistic science- “The Bible is the ultimate scientific approach” This approach would fundamentally change the way that we approach science and the scientific community has certainly not seen the need for this.

2) Religious controversy?

The debate is often framed as being between scientists and fundamental creationists
-not necessarily the case because many mainstream Christian denominations have no trouble with evolution

-thus there may be a religious controversy between different Christian beliefs

3) Philosophical controversy?
Evolution/creation debate often linked to Gallileo and Church debate

Battle between the truth of nature and the nature of truth

Creationists have tried to use ID as a wedge to show that people are either for the religious position or against it- there is no middle ground.
-The Bible is either inerrant or worthless
-Christianity or atheism
-Certainty or sketpticism
-Absolute morality or subjectivism (relativism)

Many philosophers would argue that these issues are not so black or white.

4) Political controversy?

Controversy is a struggle for power
- whichever side gets the most votes should be the side that wins
- science be damned??

Brief History of Creationism

Modern History began with the Scopes “Monkey Trial” in 1925. The ACLU orchestrated a challenge of the Tenessee state law that banned the teaching of evolution. The trial was one of the first famous trials fought in the media featuring Clarence Darrow vs William Jennings Bryan. Bryan thought that American society was undergoing moral decay that he blamed on scientific materialism as exemplified by evolution were making people question biblical authority.

Even though Bryan officially won his case (Scopes was fined $100) the general public generally agreed that evolution had won (Bryan tried to defend the Genesis version of creation on the stand and was torn apart by Darrow).

Textbook publishers were uninterested in controversy so they basically excluded evolution from biology books up until the end of the 1950s.

In the 60s the sputnik scare revitalized American Science teaching – BSCS curriculum contained evolution.

In 1973 Tenesee passed a law saying that anyone who taught evolution also had to teach the Genesis account. In 1975 this law was found unconstitutional because it was blatantly including religion

Over the next several years creationists passed laws in several states requiring the teaching of “creation science”

1982 case in Arkansas challenged a law requiring the teaching of creation science. The case brought in experts on evolution, thermodynamics and geology also experts on religion to answer the question-was creation science really science?

Judge Overton defined science as “what scientists do” and “what is accepted by the scientific community”. He dentified the “essential characteristics” of science (based on the ideals of the philosopher of science Michael Ruse)

1. It is guided by natural law
2. It has to be explanatory by reference to natural law
3. It is testable against the empirical world
4. Its conclusions are tentative; i.e., the are not necessarily the final word
5. It is falsifiable

Overton ruled that creation science fails to meet the essential characteristics and was thus not science. From religious testimony he ruled that creation science was religious so the law violated the establishment clause.

2004 Georgia case

Required placement of sticker on biology books as “a theory not a fact”
Judge ordered the stickers removed

2004 ID case- Dover Pennsylvania

The policy required students to hear a statement about intelligent design before ninth-grade lessons on evolution. The statement said Darwin’s theory is “not a fact” and has inexplicable “gaps.” It referred students to an intelligent-design textbook, “Of Pandas and People.” (which turns out to be a creationist book that basically had the words “creation” replaced by the words “intelligent design”.)
Judge Jones, a Republican and a churchgoer appointed to the federal bench three years ago. decried the “breathtaking inanity” of the Dover policy and accused several board members of lying to conceal their true motive, which he said was to promote religion. A six-week trial over the issue yielded “overwhelming evidence” establishing that intelligent design “is a religious view, a mere re-labeling of creationism, and not a scientific theory”

ID “may be true, a proposition on which the court takes no position, ID is not science.” Among other things, he said intelligent design “violates the centuries-old ground rules of science by invoking and permitting supernatural causation”; it relies on “flawed and illogical” arguments; and its attacks on evolution “have been refuted by the scientific community.”

How do Creationists and proponents of Intelligent design attempt to attack evolution?

The IDers (and other creationists) often take these approaches to get their message across

1) Try to refute evolution
Set up a false dichotomy that there are two possible explanations for the origin of the life either by evolution or created by the Judeo-Christian God. They try to show weaknesses in evolution and then having shown that evolution is wrong we are forced to accept their view of creationism. However, here are many other possible creation stories than Genesis.

2) Equal time approaches
There are two valid scientific alternatives so it is only fair to present both ideas. This doesn’t work for two reasons- (i) there are not only two alternative (Australian aboriginals and Mayans have their own creation stories)and (ii) hese other approaches are not science because they inherently bring in a supernatural creator.

3) Force of Numbers

IDers from the Discovery Instute presented a petition showing that 400 scientists dissented from Darwinism- took them 4 years to get this many signatures. 128 signees were Biologists and virtually none of them conducted research that had anything to do with the subject (the one signatory I know from Tech is an Electrical Engineer).

Some scientists responded with The Four Day Petition, whose name A Scientific Support For Darwinism is an allegorical reference to the Discovery Institute's A Scientific Dissent From Darwinism, a petition that took four years to generate just over 400 signatories. This project, The Four Day Petition, ran from Sept 28th , 2005 to October 1st , 2005. R. Joe organized the Four Day Petition with no outside funding or professional society’s assistance and generated 7,732 verified signatories of concerned scientists, all by word of mouth (well e-mail actually). Of those signatories 6,965 are US residents including 4066 with a PhD.
“My genuine thanks to the thousands of you who felt strongly enough about this petitions statement to make the time during those four days to pass the word onto your personal network of peers. The response to your efforts was tremendous. Your efforts resulted in a response 1809% higher than the Discovery Institutes at a rate 697,000% faster. It is also interesting to note that the Discovery Institute budget is $4,000,000 a year while mine is, well non existent J These results are not bad my friends, not bad at all.”

4) Because Creationists have repeatedly had their ideas judged to be a religious they have tried to argue that evolution is really a “secular religion”

5) The Kansas Board of Education has taken a couple of clever strategies. They eliminated evolution from the state science standards. Teachers remain free to teach it, but won’t be tested on it which basically eliminates it from the curriculum. When in 1999, the board eliminated most references to evolution, a move Harvard paleontologist Stephen Jay Gould said was akin to teaching "American history without Lincoln."

The Kansas School Board then tried a new approach and rewrote the definition of science, so that it is no longer limited to the search for natural explanations of phenomena.

No wonder - "The 10 Worst Jobs in Science," as listed by Popular Science magazine, October 2005: #3 is Biology teacher in Kansas

Update

Hello Everyone,

I have returned from Malaysia and Big Bend so I guess that it is time to get back to work. Visiting Malaysia was an incredible experience. I spent about a week at Krau Wildlife Reserve working with researchers studying bat ecology. I have never seen a true rainforest before and I have to admit that after a week I still couldn't see the trees for the forest. We would to out every night and morning to check the trap for bats. The bats were really cool (some of them had bodies that was smaller than my thumb). I spent a day in Kuala Lumpur meeting with folks at the University of Malaya which was interesting. Canoeing down the Rio Grande through Big Bend was an ideal way to spend my spring break. Taking a group of interested students out in the field is obviously the best way to learn so I was a little embarassed this morning when I needed to meet with them in a room using Powerpoint.

Obviously, I am extremely far behind. I will try to take a serious look at all of your midterms by the end of the weekend and get back to you with feedback. After I take a look at the midterms I will have a better idea exactly what I would like you to do as a final project. I will have more info for you next week.

Invasive Species

Our understanding of most of the current environmental issues facing us would probably be improved with a stronger understanding of basic ecology. Environmental issues, such as invasive species, provide opportunities to apply what we have learned in an applied context.

Invasive species can have profound effects on an environment. Because the resident species have had no evolutionary history with the invader it is possible that the resident species are highly susceptible to the negative effects of an invader (e.g., they have no defenses agaist a predator or a disease). Last summer I saw first hand how evolutionary history can influence interactions bewteen species. The Galapagos Islands are so isolated from continental South America that no large predators have been able to colonize the archipelago. Thus, when we would go hiking on the Galapagos Islands, the birds and animals living there literally showed no fear so that we were able to approach them very closely (I used to be impressed at all of the amazing photos I have seen of birds on the Galapagos Islands, but now I know that the photographer was only two feet away). Imagine what would have happened had a predator been introduced; the fearless animals would have been easy prey to an exotic predator.

Further Info

1) Here is a link to a presentation that I made for my seminar on the Rio Grande River. It provides general information about invasive species, how species can harm communities, and efforts that people have used to try to control invasive species. It also discusses some examples of species that have invaded Texas.

http://www.slideshare.net/secret/bL1TCLiLtoH5Np

2) Here is a link to a presentation that I made for my seminar on the Rio Grande River discussing the invasive tree, tamarisk (Salt Cedar). Tamarisk is an important invasive species in riparian areas of the western US and has become an important environmental issue in the region. There is a lot more detail in this presentation than you need to worry about.

http://www.slideshare.net/secret/CxG30GwOj6yRr7


Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- discuss the variety of mechanism through which novel species are introduced into a community (TEKS 112.43. 12B & 12E and TEKS 112.44. 4C, 4D, & 4E)

- identity examples of introduced species in your own area

- identify examples where introduced species have caused economic and environmental damage to an ecosystem (TEKS 112.43. 12B & 12E and TEKS 112.44. 4C, 4D, & 4E)

- explain why introduced species might often have large negative effects in communities (TEKS 112.43. 12B & 12E and TEKS 112.44. 4C, 4D, & 4E)

- discuss potential ways to limit invasions or to remove novel species (TEKS 112.43. 12B & 12E and TEKS 112.44. 4C, 4D, & 4E)

Biodiversity

Biodiversity is a complicated concept because it can apply at so many different levels.

Further Viewing

I have been working to develop curricular materials to teach elementary students, their teachers, and college students about biodiversity, so I have presentations aimed at a variety of different levels. Hopefully, there will be elements in some of these presentations that will help you to better understand biodiversity and maybe use in your courses.

1) Here is a slideshow that I prepared for an ecology class that I taught last spring that introduces the concept of diversity in general before introducing biodiversity. In addition to a brief discussion of diversity at the genetic level, thus presentation focuses in diversity at the community level and introduces such important concepts as species richness, species diversity, and evenness.

http://www.slideshare.net/secret/4GyUbOQ0pXY5uC

2)Here is a slideshow that my ecology students and I developed to try to introduce biodiversity to elementary students. This presentation includes species definitions, classification, and a discussion of the value of diversity.

http://www.slideshare.net/secret/4wHpDC3GnCZ61c

3) Here is a slideshow that I prepared for students in my ecology class that focuses on the mathematical indices that we use to measure species diversity and evenness. I don't know if this is at the appropriate level for your students, but it is an excellant topic to integrate biology and math.

http://www.slideshare.net/secret/wDiDEN5QiEQV8V

4) Here is an exercise that I developed to teach my ecology class about biodiversity. My plan was to develop an activity that would mimic how we might try to teach this concept to younger kids. I thought that I was very clever coming up with an activity using candy, but then I learned that the Lubbock ISD doesn't allow candy in the classroom (that just left more candy for me). This is a fairly high level, but parts of it might be useful for your students.

http://www.slideshare.net/secret/JshtMR5gndzPEU

5) Here is an exercise that I developed to introduce the topic of biodiversity to elementary students using the characters from Finding Nemo. It is fairly basic, but it would be great if all middle school and high school students were able to do this work.

http://www.slideshare.net/secret/3S2mU4jlcVjsoc

Species Diversity

Ecologists are often interested in the species diversity. Diversity is a fairly complex concept because diversity in a system can be influenced by more than one factor.

Species diversity if influenced by species richness and by species evenness. Biologists have developed equations that allow them to quantify species diversity and evenness (these are known as diversity indices). I introduce two of these diversity indices, the Shannon Index and the Simpson's Index, in the slideshows I have included here.

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- define biodiversity and explain the various components of diversity including genetic diversity, species diversity, and functional diversity (TEKS 112.43. 7B)

- distinguish between species richness, species diversity, and evenness and be able to use indices to quantify these components of diversity.

- discuss the factors that influence diversity in an ecological community (TEKS 112.43. 7B, 12A, & 12E and TEKS 112.44 6C)

- explain why biodiversity is important (TEKS 112.44 4E)

- compare threats to biodiversity in their local region with those in a distant region (TEKS 112.44 4E)

Assignment for Midterm Exam

So far in this class I have tried to cover some of the main topics in ecology. Often we choose examples from different environments to discuss each of these topics. However, I think that our students would benefit more from seeing how these topics can be applied to the same environment.

Choose an "area" (I suggest that the more specific the better- e.g. don't just choose "the desert" choose a particular location in a particular desert)that either you are particularly interested in or that you think that your students will be interested in learning more about. Your area can be terrestrial, marine or aquatic or tropical, temperate or polar. The discussions of biomes and ecoregions found in the EoE may help you to choose an area.

Think about how the following topics relate to your "area".


1) Physical Environment
- discuss the causes of climate in your area

2) Adaptations of Plants and Animals to the Physical Environment
- discuss morphological, physiological, and behavioral adaptations to the physical environment of your area

3) Population Regulation
- discuss the factors that regulate population sizes in your area

4) Species Interactions
- discuss some important interactions between species in your area

5) Adaptations to Biotic Interactions
- discuss examples of morphological and behavioral adaptations that help organisms in their interactions with other species

6) Food Webs, Indirect Interactions, Keystone Species
- discuss the food web of your area- discuss important indirect interactions and keystone species

7) Energy Flow
- discuss pattern of energy flow in a chosen environment

8) Nutrient Cycling
- discuss either nutrient cycling or the hydrologic cycle in your area

9) Ecosystem Services
- discuss ecosystem services provided by species in your area

Assignment
You assignment for this exam is to write a paper discussing 5 of the 9 topics listed above. Not all topics will be equally interesting or accessible in different areas (and you may be more interested in teaching about some of these topics than others). Your audience for this paper is the parents of your students. Imagine that you are trying to stimulate them to be more involved in their children's educations by providing them with enough background information about biology that they can understand what their children are learning.

All exam papers must include
(i)a discussion of topic 1 (physical environment)
(ii) a discussion of at least one section studying adapations (topics 2 or 5, you may discuss both)
(iii)at least one section discussing factors at the ecosystem level (topics 7, 8, or 9)

Feel free to incoude Figures, Graphs, or whatever materials you think would be useful.

DUE DATE

All assignments should be emailed to me and should arrive at in my mailbox no later than 10:00 PM on Monday February 23rd, 2009.

Note

This assignment makes perfect sense to me, but I imagine that I might not have explained perfectly well what I would like you to do. Please let me know if you have any questions.

Course Update and Midterm Exam

Hello Everyone,

I realized, with horror, how long it has been since I have last posted. I have been focusing on getting through the test period for my large Introductory Biology class (we have a test and then the students have an option to take a "retest" on the same materials the following), I have definitely learned that "the squeaky wheel gets the grease" and "out of sight, out of mind" have been running my life lately. Hopefully, I am nearly caught up with posts for this week's material. I am sorry for not posting for so long.

From the beginning, I have been a bit skeptical about being able to create an effective learning environment without seeing people face to face. I realize that I probably should have required a great deal more student involvement on a regular basis (e.g., requiring students to post weekly on the blog), but I hate requiring busy work. Hopefully, you have been able to read the material and are learning some things that will be useful in your classes. I encourage you all to give me feedback about how the course is going and suggestions about what I can do to make this course as useful possible.

Midterm Exam

When I looked at the syllabus it told me that your first midterm is due on February 21st. Because my intent was to allow you plenty of time to for you to work on the midterm exam, I would like to delay the due date for the First Midterm Monday February 23rd which will at least give you the weekent to work on the exam. I will post the exact form of the midterm exam sometime tomorrow (Monday) so that you will have a full week to work on the assignment.

Landscape Ecology

Landscape Ecology is a relatively new field (that was certainly not included in introductory level Ecology courses when I was in college or graduate school). However, as humans greatly alter and degrade the environment it has become critical that we understand how altering the spatial distribution of habitats affects ecology

Habitat Framentation

Factors such as deforesttation have reduced once uninterupted areas of habitats into smaller islands of native habitat surrounded by a sea of altered habitat. Habitat fragmentation is an issue that is especially important to conservation biologists who have to determine (1) what are the implications of habitat fragmentation to biodiversity and (2) how should we design conservation reserves? (i.e, if a government is willing to put so much land aside as reserves should we make several small reserves or one large reserve?).

Effects of Habitat Fragmentation on Malaysian Bat Diversity

In about a week and a half I will be heading out to Malaysia to work with researchers studying the ecology of rainforest bats. Although I am involved in this project because of my interests in science education, by co-worker Tigga Kingston is interested in bat conservation. She has been trapping bats in Krau Wildlife Reserve, an area that has been protected from logging, to see what bat communities are like in undisturbed forests. Because Malaysia has one of the highest deforestation rates in the world (see photo at top of this post) undisturbed forests are boing cut (primarily for agriculture) which may have profound effects on the bat community.

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- define the field of landscape ecology
- discuss how an understanding of landscape ecology can be useful for land-use planning and conservation biology

Free Learning

We are coming to the end of the basic ecology portion of the course and preparing to talk about biodiversity and environmental issues. Although deforestation is not an issue that I want to focus on in this course, it is an important issue that I think you, and your students should know about.

FYI here is a link to a slideshow on Deforestation that I have prepared as part of our Malaysian Bat Project. But don't think that deforestation is only an issue of concern in the tropics. Most people on the Southern High Plains would be surprised to know that this area once hosted the largest (in terms of area) oak forest in the United States which has not been almost completely removed.

http://www.slideshare.net/secret/eJe8rHdu5JC0kb

Ecosystem Services

Ecologists recognize that the ecosystem naturally provides many services to humans that we take for granted.(for some more simple info on this topic look at http://www.actionbioscience.org/environment/esa.html and for more detailed information check out http://www.eoearth.org/article/An_Introduction_to_Ecological_Economics:_Chapter_3)

Ecologists have begun to try putting a monetary value on the services that the ecosystem provides us. In 1997 a number of scientists valued ecosystem services at between 16 trillion to 5 trillion dollars each year (how many stimulus and bailout packages is that going to equal???). Obviously, this is a very difficult number to come up with and their methodology has been criticized.
http://www.eoearth.org/article/Value_of_the_world%C3%A2%C2%80%C2%99s_ecosystem_services%3A_the_influence_of_a_single_paper
However, it is important for us to be aware of many of the values that ecosystems provide to us and what services might be lost when we lose species and damage ecosystems.


Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- discuss ecosystem services provided by species in both terrestrial and marine environments (TEKS 112.44 5E)

Global Carbon Cycle and Global Warming

Human activity, including burning fossil fuels, deforestation, and buring trees, has altered the global carbon cycle. Carbon dioxide is an example of a greenhouse gas. (Greenhouse gas- http://www.eoearth.org/article/Greenhouse_gas). Thus, if the concentration of carbon dioxide has increased and carbon dioxide is a greenhouse gas, then we might predict that global temperatures should be increasing. Thus alternation of the global carbon cycle is the proposed cause of global climate change (global warming). Although global warming is not a focal point of this course, I think that it is important that you are able to address this issue intelligently with your students. Here is some info that you might find useful

Obviously, global climate change is a very imporant issue facing us today. If you are alive and paying any attention, then you probably know that there is some disgreement out there about (1) whether global warming is occuring, (2) if it is occuring is it a natural occurence or is it caused by humans, and (3)what should we as individuals and a society do about these issues. As I mentioned in class, it is very important that you understand what components of the debate are facts and what components of the debate are based on mathematical models or other forms of argument. I think that it is important that you should be able to explain to other people why scientists will never be able to conduct the experiment that will nail down whether or not humans are causing global warming (we have only one earth).

Unfortunately, there is a lot of misinformation about this topic. For example, on Thursday February 5th there was a letter to the Lubbock Avalanche Journal about global warming that clearyly contained some misstatements of fact. I think that it is important for you to have access to good information. Here are some links to what I consider to be some of the best and most reliable sources of information about this topic. Although some of these articles go into much more detail than are required for this class you should know where to find reliable information about this topic.

Further Reading

Carbon cycle- http://www.eoearth.org/article/Carbon_cycle

Global warming- http://www.eoearth.org/article/Global_warming

Global warming Frequenty Asked Questions- http://www.eoearth.org/article/Global_warming_frequently_asked_questions

Climate change FAQ- http://www.eoearth.org/article/Climate_change_FAQs

Intergovenmental Panel on Climate Change- http://www.eoearth.org/article/Intergovernmental_Panel_on_Climate_Change_%28IPCC%29

IPCC Assessment for Policymakers- http://www.eoearth.org/article/IPCC_Fourth_Assessment_Report%2C_Working_Group_I%3A_Summary_for_Policymakers


Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- diagram the global carbon cycle
- discuss how humans have altered the global carbon cycle
- discuss how the atmospheric concentration of carbon dioxide varies annually
- discuss the proposed relationship between human caused changes in the global carbon cycle and global warming
- discuss alternative causes of global warming
- discuss the experiment that would be required to determine whether or not human activity is the cause of global warming
- articulate and defend their own personal view of how they intend to deal with the global warming issue

Saturday Update

Not surprisingly, my home, Lubbock, TX, is not the center of enviromnetal awareness. In fact, reading articles in our local media denying global warming is a fairly regular occurance. The Saturday(February 7, 2009) issue of the Lubbock Avalance Journal contains another letter to the editor talking about global warming. The letter right refers reader to a site, www.petitionproject.org, where they claim that over 30,000 scientists (9000 of them have Ph. D.s) have signed a petition "firmly disagreeing with global warming theory". I would be interested in what you guys thought about the information available on this site relative to the info on the posts I have listed above.

Ecosystem Ecology- Global Carbon Cycle

Some nutrients cycle at a global level. We will use a simple example of the carbon cycle to illustrate an example of a global cycle (see figure at top of this post).

At the global level the major locations for carbon are living organisms, the atmosphere, water, and rocks. The two most important biological causes of movement between one reservoir and the next are photosynthesis and cellular respiration.

1. Photosyntheis- moves carbon from the atmosphere (for terrestrial organisms) or water (for aquatic organisms) to living organisms. Carbon dioxide ===> glucose

2. Cellular Respiration- moves carbon from living organisms to the atmosphere or water.

glucose ===> carbon dioxide.

Carbon in the Atmosphere

The major source of carbon in the atmosphere is carbon dioxide. Historically, the rate at which carbon dioxide was added to the atmosphere was about equal to the rate at which carbon dioxide was removed from the atmosphere were about equal. Thus, over time the atmospheric contentration of carbon dioxide didn't change very much.

Human Alteration of the Global Carbon Cycle

Humans have altered the global carbon cycle in three main ways.

1) By burning fossil fuels (e.g., gasoline in our cars and coal in our power plants) we have increase the rate at which carbon is moved from rocks to the atmosphere.

2) Deforestation- By cutting down trees for agriculture or development we have reduced the number of plants conducting photosynthesis. Thus, we have decreased the rate at which carbon is moved from the atmosphere to living organisms.

3) By burning trees after deforestation we have increased the rate at which carbon moves from lving organisms to the atmosphere.

Thus, humans have increased the rate at which carbon is being added to the atmosphere while decreasing the rate at which carbon is removed from the atmosphere.

Prediction- the amount of carbon in the atmosphere should be increasing.

Test of this prediction- scientists in Mauna Loa, Hawaii have tested this prediction by measuring the amount of carbon dioxide in the atmosphere over the past 50 years.

MaunLoa Curve- http://www.eoearth.org/article/Mauna_Loa_curve

This curve shows two things. First, that the concentration of carbon dioxide in the atmosphere has indeed increased over time. Second, that there is seasonal variation in the concentration of carbon dioxide in the environment. Carbon dioxide is most abundant in the atmosphere in the North American winter and lowest in the North American winter. This pattern is caused by seasonal variation in the amount of photosynthesis. In the summer, when photosynthetic rates are the highest, carbon dioxide is removed from the atmosphere at a high rate which reduces the amount of carbon in the atmosphere. Because there is more land mass in the Northern Hemispere and most photosynthesis happens on land, the global pattern is determined by seasons in the Northern Hemispere (this is truly a global cycle, carbon dioxide move so quickly though the environment that the conentration is virtually the same all over the world).

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- diagram the global carbon cycle and be able to explain how human activity has altered this cycle (TEKS 112.43. 12A).


What is Happening to the Rate Carbon Dioxide is Being Added to the Atmosphere?

Here is an article from the Associated Press entitled- Climate Warming Gasses Rising Faster than Expected that was published yesterday. Chris Field, one of the scientists quoted in this article, was one of my professors at University of Utah.

CHICAGO (AP) -- Despite widespread concern over global warming, humans are adding carbon to the atmosphere even faster than in the 1990s, researchers warned Saturday. Carbon dioxide and other gases added to the air by industrial and other activities have been blamed for rising temperatures, increasing worries about possible major changes in weather and climate.

Carbon emissions have been growing at 3.5 percent per year since 2000, up sharply from the 0.9 percent per year in the 1990s, Christopher Field of the Carnegie Institution for Science told the annual meeting of the American Association for the Advancement of Science.

''It is now outside the entire envelope of possibilities'' considered in the 2007 report of the International Panel on Climate Change, he said. The IPCC and former vice president Al Gore received the Nobel Prize for drawing attention to the dangers of climate change.

The largest factor in this increase is the widespread adoption of coal as an energy source, Field said, ''and without aggressive attention societies will continue to focus on the energy sources that are cheapest, and that means coal.''

Past projections for declines in the emissions of greenhouse gases were too optimistic, he added. No part of the world had a decline in emissions from 2000 to 2008.

Anny Cazenave of France's National Center for Space Studies told the meeting that improved satellite measurements show that sea levels are rising faster than had been expected. Rising oceans can pose a threat to low level areas such as South Florida, New York and other coastal areas as the ocean warms and expands and as water is added from melting ice sheets.

And the rise is uneven, with the fastest rising areas at about 1 centimeter -- 0.39 inch -- per year in parts of the North Atlantic, western Pacific and the Southern Ocean surrounding Antarctica, she said.

Also, highly promoted efforts to curb carbon emissions through the use of biofuels may even backfire, other researchers said. Demand for biologically based fuels has led to the growing of more corn in the United States, but that means fields were switched from soybeans to corn, explained Michael Coe of the Woods Hole Research Center. But there was no decline in the demand for soy, he said, meaning other countries, such as Brazil, increased their soy crops to make up for the deficit.
In turn, Brazil created more soy fields by destroying tropical forests, which tend to soak up carbon dioxide. Instead the forests were burned, releasing the gasses into the air. The increased emissions from Brazil swamp any declines recorded by the United States, he said.

Holly Gibbs of Stanford University said that if crops like sugar and oil palm are planted after tropical forests are burned, the extra carbon released may be balanced by lower emissions from biofuel in 40 to 120 years, but for crops such as corn and cassava it can take hundreds of years to break equal.

''If we run our cars on biofuels produced in the tropics, chances will be good that we are effectively burning rainforests in our gas tanks,'' she said.

However, there could be benefits from planting crops for biofuels on degraded land, such as fields that are not offering low productivity due to salinity, soil erosion or nutrient leaching.

''In a sense that would be restoring land to a higher potential,'' she said. But there would be costs in fertilizer and improved farming practices.

In some cases simply allowing the degraded land to return to forest might be the best answer, she said.

Ecosystem Ecology- Nitrogen Cycles Within an Ecosystem

Ecosystem ecologists define nutrients as biologically important elements (e.g., C, N. P, S). Nutrients can cycle either within ecosystems or globally

Nitrogen Cycle

We will consider a very simple example of the nitrogen cycle to illustrate how nutrients cycle within an ecosystem (ie., nutrient cycle within a prairie in Kansas or within a rainforest in Brazil).

Plants pick up nitrogen from the soil, herbivores get their nitrogen from eating plants, and carnivores get their nitrogen by eating herbivores. When organisms die there is nitrogen held in their dead bodies. Decomposers get their nitrogen from dead bodies and return nitrogen to the soil where it can be picked up by plants. Thus, it is possible for the same atom of nitrogen to recylce through the ecosystem over and over.

Ecosystem ecologists are interested in understanding how much nitrogen is found in plants, animals, soil, etc. and the rate at which nitrogen moves from one place to another.

What factors can influence the movement of nitrogen through and ecosystem and why is this important? Decomposers are responsible for moving nitrogen from dead bodies of organisms to the soil. The major decomposers, fungi and bacteria, thrive in warm and wet environments. Thus, we might expect the rates of decomposition in tropical rainforests to be much faster than in the desert. Thus, nutrients in dead bodies are quickly returned to the soil in tropical rainforests where they are quickly picked up by plants. Alternatively, the slow rate of decomposition can tie up nitrogen in dead bodies of plants so that nitrogen is not available for plant growth.

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- diagram the nitrogen cycle within an ecosystem and explain how the rate of movement from one reservoir to the next can vary between environments (TEKS 112.43. 12A & 12E).

-develop curricular material to illustrate nitrogen cycling withing a chosen environment (TEKS 112.43. 12A & 12E).

Ecosytem Ecology- Energy Flow

Ecosystems include all of the biotic components that we talked about in a community as well as abiotic characteristics. Ecosystem ecologists focus on the flow of energy and nutrients through the ecosystem.

Energy Flow

Energy is required to do the "biological work" needed to keep species alive. Almost all of the energy used by biological organisms on earth originates as electromagnetic energy from the sun that is then converted into chemical energy by the process of photosynthesis. Energy then flows up the food chain from one tropic level to the next.

Secondary Consumers
^
Primary Consumers
^
Primary Producers

Photosynthetic organism (plants and photosynthetic bacteria) are known as "Primary Producers" and they make up the bottom of most food chains. Species that get their energy by eating primary producers are known as "Primary Consumers". Organims that get their energy by eating primary consumers are known as "Secondary Consumers".
Thus, energy moves up the food chain from primary producers to primary consumers to secondary consumers.

All organisms are releasing energy to the atmosphere in the form of heat (you are releasing heat right now by the effort you are making to keep your eyes open).

When organims die energy is held in their dead bodies. Decomposers "feed" on the energy held in dead bodies and decomposers also release energy to the atmosphere as heat.

3 Key Facts About Energy Flow

1. Energy enters the system as sunlight energy, moves up the food chain, and is ultimately lost as heat.

2. The flow of energy is one way only.

3. The flow of energy from one trophic level to the next is inefficient. Only approximately 10% of the energy held in one trophic level is passed on to the level above it. The

Energy Pyramid

Because the flow of enrgy up the food chain is inefficient, the amount of energy available in each trophic level decreases as you move up the food chain. This can be shown in a diagram known as an "energy pyramid" (see example at the top of the post).

This is important for two reasons. First, there is a limit to how long food chains can be because there is eventually not enough energy available to add another level to the chain. Second, the amount of energy in a trophic level influences the population size of species in the trophic level above it. For example, all else being equal we expect population sizes of predators to be smaller than the population sizes of herbivores because they have less energy to feed on.

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- identity the source of most energy used by biological organisms on earth and explain the energy transformations experienced by this energy (TEKS 112.43. 9D,12A, & 12E and TEKS 112.44. 6A, 6B, & 6D)

- diagram the energy pyramid and explain why it has the shape it does and how it affects population structure at different trophic levels (TEKS 112.43. 9D & 12A and TEKS 112.44. 6B, 6C, & 6D).

- diagram food chains and food webs from a variety of environments (TEKS 112.43. 9D, 12A, & 12E and TEKS 112.44. 6B, 6C, & 6D).

- develop curricular materials to illustrate the food web and pattern of energy flow in a chosen environment (TEKS 112.43. 9D, 12A, & 12E and TEKS 112.44. 6B, 6C, & 6D).

Community Ecology- Food Webs

The take home point of my classes on Community Ecology is the "the world is complicated!" It is relatively simple to think about species interactions when we are studying interactions between only two species at at a time. However, species exist in very complex food webs. All species are potentially a source of food for other species and all species (except for plants) must use another species as food. (of course, plants are competing with each other for light, nutrients, and water!).

Direct Effects

Species can directly influence the growth rate or population size of another species directly by (1) acting as a source of food, (2) by using the other species as a source of food, or (3) by interference competition.

Let's try an example. Imagine that we are interested in studying the ecology of the Serengetti National Park in Tanzania. To keep things simple lets say that (1) lions eat wildebeasts, and (2) leopards eat wildebeasts. If we increase the population size of lions, then we would expect the population size of their prey (say wildebeasts) to decrease because there are more lions preying on wildebeasts. Alternatively, if we increase the population size of wildebeasts then we would expect the population size of lions to increase because there is less food for lions. These would both be examples of "direct effects"

Indirect Effects

What happens to the population size of leopards if we increase the population size of lions? If we assume that there is not interference competition going on between lions and leopards then we see that there are no direct effects of lions on leopards. However, it is easy to see that changing the population size of lions will affect the population size of leopards. If we increase the population size of lions that would decrease the population size of wildebeasts and decreasing the population size of wildebeasts would decrease the population size of leopards. Thus, lions have an indirect effect on leopards through their effects on the population size of wildebeasts. Lions and leopards are expoloitative competitors which tells us that exploitative competition is an indirect interaction.

The World is Complicated

Thus, all species are being influenced by a variety of direct and indirect effects. Thus, altering the population size of a single species may have effects on many other species and the population size of a single species can be influenced by many other species.

Actually determing how changing the population size of a specific species will affect the rest of the community is difficult to determine without careful long-term manipulative experiments in the field. These studies are costly and have therefore only been conducted in a few ecosystems.

Keystone Species

One of the interesting outcomes of studies of complex interactions is the discovery of "keystone species". Emmet Duffy's article on the EoE discusses some of the classic examples of keystone species

Expected Learning Outcomes (slightly modified from the Ecology Reader)

At the end of this course a fully engaged student should be able to

- determine the position of a species in the food chain (TEKS 112.43 10D, 12B, 12E and TEKS 112.44 6B)

- distinguish between direct and indirect effects and provide examples of indirect ecological effects occurring in specific communities (TEKS 112.43 12B)

- identify examples of keystone species (TEKS 112.43 12B and TEKS 112.44 4D, 4E)

Community Ecology- Species Interactions

Community Ecology is one of fhe most interesting topics in all of ecology (in my opinion). The major biological interactions between species (competition, predation, and mutualism)are important because they can influence aspects of community structure such as species diversity, aspects of population biology including population size, and act as important selective pressures influencing the behavior and morphology of species.

Competition

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- identify and explain examples of exploitative and interference competition from a variety of environments (TEKS 112.43. 12 B & 12 E and TEKS 112.44. 4 A).

- define the competitive exclusion principle and explain how this principle can influence patterns of community structure (TEKS 112.43. 12 B & 12 E).

- develop curricular materials to illustrate competition in a particular environment (TEKS 112.43. 12 B & 12 E and TEKS 112.44. 4 A).

Predation

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- identify and explain examples of predation, herbivory, and parasitism from a variety of environments (TEKS 112.43. 12 B & 12 E and TEKS 112.44. 4A).

- identify examples of morphological and behavioral adaptations that animals have to help capture their food (TEKS 112.43 7B, 12B)

- identify examples of morphological, biochemical, or behavioral adaptations that animals have to protect them from predators (TEKS 112.43 7B, 12B)

- explain the role that predation plays in regulating population sizes of species (TEKS 112.43. 12 B & 12 E and TEKS 112.44 7A).

- explain how predation can influence the species richness of a community (TEKS 112.43. 12B)

- develop curricular material to illustrate predation in a chosen environment (TEKS 112.43. 12 B & 12 E and TEKS 112.44. 4A).

Mutualisms

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- identify and explain examples of mutualisms from a variety of habitats (TEKS 112.43. 12 B and 12 E).

- explain the role that mutualisms can play in determining community structure (TEKS 112.43. 12 B and 12 E).

- develop curricular materials to illustrate mutualism in a chosen environment (TEKS 112.43. 12 B and 12 E).

Human Population Growth

I have spent a lot of time telling you that exponential growth is an unrealistic model of population growth. Interestingly, human populations have experienced exponential-like growth. How can this be?

What makes humans different from other species?

In other species per capita birth rates and per capita deaths rates are density dependent. However, as human populations have increased there has been no corresponding decline in per rates or increase in death rates. What makes humans different from other species?

Humans have the ability to alter their environment so that they can avoid the density dependent effects on birth and death rates. 1) Humans have increased food production by improvements in agriculture (e.g., irrigation, fertilization, mechanized farming, genetically improved crops). 2) Humans have been able to decrease death rates by improvements in medicine and public health (things as simple as not pooping in the water you drink helps a lot!). 3) Humans have elimnated most human predators (ocassionally, someone gets killed by a shark or a mountain lion).

Where is human population growth occuring?

The rates of human population growth are not the same in all regions. Today, human populations are increasing in size much faster in developing countries (e.g., Mexico, other countries in Central America, Africa, and Southeast Asia) than they are in developed countries (e.g, USA, Canda, Western Europe). The figure at the top of this post shows the patterns of population growth in developed and developing nations.

Thus we see that populations are increasing most rapidly in the countries that are least able to deal with a rapidly increasing population. See "Population Challenges-The Basics" that can be downloaded from the Population Institute's website.
http://www.populationinstitute.org/population-issues/index.php

Human Population Growth Proble?

There is a great deal of debate about whether increasing human populations are a problem or not, and if they are what should be done about it. Unfortunately, we don't have time to discuss this issue in very much detail in class. My personal opinion is that we have too many people consuming too many resources and the last thing that we need are billions more people living on the planet. This is an issue that I am always intersted in talking more about if you would like to chat.

Further Reading

See the article "Human Population Explostion" from the EoE.
http://www.eoearth.org/article/Human_population_explosion

Pay particular attention to the "demographic transition".

Really Cool Video

Here is a link to a YouTube video on "World Population" The first minute and a half or so is a little boring, so you can skip over it if you wish. However, I think the animation showing when and where human population growth has been occuring is really cool.

http://www.youtube.com/watch?v=4BbkQiQyaYc

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- describe patterns of human population growth in developed and developing nations
- discuss some reasons why the pattern of population growth in humans is so different from that in other species
- describe the demographic transition
- discuss their own personal view of human population growth.

Fun With Graphs- Quiz Yourself

Here are some questions that I have designed to let you know if you are understanding the graphs well enough to meet the course expected learning outcomes. I suggest that you do not try to answer these questions until you have thoroughly reviewed all of the information about the population ecology graphs. (I will put the answers for the multiple choice questions at the bottom of this post, for the others you need to find out whether your answers are correct or not).
1. What are the correct axes for a graph showing how population growth rate depends on population size in logistic growth?
a) x- N y- t
b) x- N y- dN/dt
c) x- dN/dt y- N
d) x- dN/dt y- t
e) x- N y- r

2. Which of the following best describes the graph that shows how the per capita growth rate varies over time in exponential growth?

a) the per capita growth rate decreases over time
b) the per capita growth rate increases over time
c) the per capita growth rate does not change over time
d) the per capita growth rate increases until it reaches a maximum and then decreases to zero when the population reaches the carrying capacity
e) the per capita death rate is initially very negative and gets less negative over time.

3. What would I ask to make you draw this graph

a) show how the population size varies over time in logistic growth when the initial population size is much smaller than the carrying capacity

b) show how the population growth rate depends on the population size in logistic growth when the intitial population is much smaller than the carrying capacity

c) show how the population size depends on population size in logistic growth when the initial population size is much smaller than the carryuing capacity

d) show how the population size varies over time in logistic growth when the intitial population is much larger than the carrying capacity

4. What are the axes of a graph showing how the per capita growth rate depends on the population size in logistic growth?
a) x- logistic y- exponential

b) x- logistic y- r

c) x-N y-r

d) x-r y-N

e) x-N y-dN/dt

5. Which of the following is true when populations are at their carrying capacity?

a) N = 100 individuals

b) dN/dt = 0

c) b > d

d) b = d

e) b and d

6. Describe how the population growth rate varies over time in logistic growth when the intial population size is much larger than the carrying capacity.

7. Draw the graph that shows how the population size varies over time in logistic growth when the initial population size is much smaller than the carrying capacity.

Answers. 1.c, 2.c, 3.b, 4.c, 5.e

Fun With Graphs- Logistic Growth

We are trying to develop a mathematical model that helps us to understand patterns of population growth. So far our first attempt, the exponential growth model, did not help us to understand population growth (for reasons that I hope that you understand by now).

The "Real" world

In our attemtp to think about population growth in the real world, we attempted to examine how per capitat birth rates and per capitat death rates should vary as population size varies. The model that describes this pattern of growth is known as the logistic growth model. It is important to realize that although this model is much more realistic, and therefore useful to us, than the exponential growth model, the logistic growth model still only exmaines what I call "the theoretical real world". That is, this model applies to our ideas about how populations should generally behave and do not thus relate directly to studying the population sizes of white tailed deer in central Texas or parrot fish on a coral reef in Fiji. These real world situations are much harder to understand than the simple "idealized" populations that we need to cover in this class (it is definitely more complex than you need to be able to explain to your students).

Logistic Growth

We have discussed why, in the real world, r should decrease as population sizes increase. If this is the case then there is a population size at which the per capita birth rate equals the per capita death rate. We call this population size the carrying capacity.

1) When populations are smaller than the carrying capacity we expect them to increase in size until they reach the carrying capacity.

2) When populations are larger than carrying capacity we espect them to decrease in size untile they reach the carrying capacity.

3) When the population size equals the carrying capacity we expect no change in the size of the population.

The logistic growth equation is a mathematical equation developed by biologists to describe patterns of population growth consistent with the ideas above. Before focusing on the biological isights that we can gain from the logistic growth model (the real purpose of everything we have been doing) it is important to really understand patterns of logistic growth. Hopefully, this powerpoint presentation will help you understand these patterns better.

Powerpoint Presentation

Click here for a powerpoint presentation entitled "Fun With Graphs- Logistic Growth"
http://www.slideshare.net/secret/gyB3cjnSplLw41

Fun With Graphs- Exponential Growth

How do I know which graph to draw?

1) In the population ecology portion of this course we will be discussing two models of population growth- exponential growth and logistic growth. Thus, you need to know which growth model you are describing before you know which graph to draw.

2) You can't draw a graph until you know what the axes are.

Hopefully, this is a review, but it is probably worth talking about. The x-axis (the horizontal axis) is known as the independent variable. The y-axis (the vertical axis) is the dependent variable. Changing the value of the independent variable results in a change in the dependent variable. It DOES matter which variable goes on which axis so try to get it right.

In population ecology there will be two main independent variables that we are interested in studying. Because we are interested in patterns of population growth, we will often want to observe how variables change over time. Time is always the independent variable, so it always goes on the x-axis. Sometimes we are interested in how parameters depend on population size. In this case, population size is always the independent variable.

Powerpoint Presentation

This powerpoint presentation "Fun With Graphs: Exponential Growth) reviews the graphs you are expected to be able to draw, understand, and interpret.
http://www.slideshare.net/secret/mavlOD8flFs67G

Population Ecology II

This section on population ecology is the topic that I am most concerned about teaching via distance. It seems easier to show you in person how I work problems than it is to try to explain in writing how to work the problems. In addition, I have always found it easier to teach math and graphing when I can give students some problems to solve and I can walk around the classroom peering over their shoulders while they work (it is fun to freak out freshmen that way!).

After you are comfortable with the paremeters that I introduced in teh Population Ecology I. blog, then I would read the articles from the EoE in the following order.

Population ecology
Exponential growth
Logistic growth
Carrying Capacity
Intraspecific competition

These articles (which I have written) attemtp to introduce the readers to the two most important mathematical models that have been used to describe simple population growth.

Exponential Growth

From the first lesson on Population Ecology we learned that the population growth rate (dN/dt) can be calculated as the product of the per capita growth rate (r) and the population size (N).

dN/dt = rN

This is the fundamental equation describing population growth and this equation is always true.

If we want to use this equation to analyze how population sizes change over time, then it makes sense to start by examining the simplest formulation of this equation which occurs when the per capita growth rate is constant. The equation dN/dt = rN when r is constant is known as the exponential growth equation and this equation describes a patter on growth known as exponential growth.

The graph plotting how population size changes over time is shown in the Exponential Growth article. This graph shows an exponential growth curve (sometimes known as the "j-curve"). If you have questions about why the graph has this shape let me know and I will try to explain it more thoroughly.

It is important that you are able to look at this graph and determine all of the information held in the graph. The exponential growth curve allows us to discuss how two parameters change over time- 1) the population size (shown by the x-axis) and 2) the population growth rate (shown by the slope of the line). I find that it is easier to discuss only one parameter at a time so let's start with the population size.

1) Over time, the population size increases (we know this because the line has a positive slope).

Now let's think about the population growth rate.

2) Over time, the population growth rate increases (we know this becasue the line gets steeper over time.

3) Over time, the rate at which the population growth rate increases over time, increases over time (we know this because the slope increases faster and faster over time).

Thus, if populations are growing exponentially then they keep increasing in size at an ever faster rate forever and ever.

Now try this-

Can you draw the following graphs?

1) plot how the population growth rate varies over time.

(hint- we have alredy described what this pattern will look like using words- just turn these words into pictures).

2) plot how the population growth rate depends on population size.

(hint- this graph is a little trickier, but we do have an equation that relates the two variables)

3) plot how the per capita growth rate varies over time.

(hint- think about what the basic assumption we made aboiut exponential growth)

4) plot how the per capita growth rate varies over time.

(see the hint from number 3)


Exponential Growth is Unrealistic

Because population sizes keep increasing at ever faster rates for ever, exponential growth does not seem to be an accurate description of population growth in most animals, plants, and microbes. If this is an unrealistic model then why did I teach it to you? I started with exponential growth becasue it is the simplest model of population growth and scientists always like to describ the world using the simplest models that they can.

Obviously, in this case we have started with a model that is too simple to realistically describe the world. What is wrong with the exponential growth model? The fundamental assumption we made about exponential growth is that the per capita growth rate is constant. This must not be a realistic assumtpion.

It is important that you understand, and are able to explain, both the mathematical reasons and biological reasons that exponential growth is an unreasonable model of population growth. I tried to explain biologically why exponential growth is unrealistic in the "Exponential Growth" article and the attached Powerpoint presentation so take a look at those.

Powerpoint presentation "Why is Exponential Growth Unrealistic?" http://www.slideshare.net/secret/IDPugQtl2wvONv


Final Thoughts

Many students find using math to think about biological concepts and using graphs to illustrate pattersn to be difficult. It is probably difficult for students because they have not had very much practice doing it. If you are comfortable using math and graphs, then most of what we are doing will not be too difficult. However, if you lack a lot of experience using math and graphs, this section might be a bit frustrating. My advice to you is to keep plugging away. Once you learn how to approach these problems, then you will find that you have developed a skill that you can use over an over again. It will, however, require some practice to develop these skills. Please let me know if you are having any problems or questions. You can post on the blog, send me an email, or if you think it will help to actually talk, then we can talk over the phone (it is frustratingly difficult to quickly and easily show you graphs electronically). I need to go educate the masses of Texas Tech, but I will be back on-line soon to talk about logistic growth (a more realistic and useful model of population growth).

Population Ecology I. Basic Parameters

Here is a brief introduction to some of the important parameters that we will need to understand to be able to study population ecology. For each of the parameters it is important that you know (1) the name of the parameter, (2) the algebraic symbol used to represent the parameter, (3) the units of measurement for the parameter, (4) how to calculate the parameter, and (r) how to describe (in words) what a particular value of that parameter means.

It is probably easiest for me to introduce these concepts using an example.

Imagine that in a population of 100 elephants that in one year 10 elephants are born and 5 elephants die.

1) Population Size (N) units- individuals. Measures the number of individuals in a population.

N = 100 individuals

In this population, there are 100 elephants.


2) Population Birth Rate (B) units- number of births per time. Measures the number of births per time that occur in a population.

B = 10 births/year

In this population, each year there are 10 births.


3) Population Death Rate (D) units- number of deaths per time. Measures the number of deaths per time that occur in a population.

D = 5 deaths/year

In this population, each year there are 5 deaths.


4) Population Growth Rate (dN/dt) units- number of idividuals per time. Measures the rate of change of the population size.

dN/dt = B - D

dN/dt = 10 births/year - 5 deaths/year = 5 individuals/year

In this population, the population size increases by 5 individuals each year.


5) Per Capita Birth Rate (b) units- births per time per individual. Measures the number of births per time averaged across all members of the population.

b = B/N

b = (10 births/year)/100 individuals = 0.10 births/year/individual

In this population, each year 0.10 babies are born for each individual in the population.


6) Per Capita Death Rate (d) units - deaths per time per individual. Measures the number of deaths per time averaged across all members of the population.

d = D/N

d = (5 deaths/year)/100 individuals = 0.05 deaths/year/individual

In this population, each year 0.005 individuals die for each individual in the population.


7) Per Capita Growth Rate (r) units = individuals/time/individual. Measure the rate of change in population size averaged across all individuals. The per capita growth rate can be calcuated two ways.

a) r = b - d

r = 0.10 births/year/individual - 0.05 deaths/year/individual = 0.05 ind/year/ind


b) r = (dN/dt)/N

r = (5 individuals/year)/100 individuals = 0.05 individuals/year/individual

In this population, each year 0.05 individuals are added for each individual in the population.


Practice Problem

In a population of 50 tigers, in one year 10 tigers are born and 20 tigers die. What is B, D, dN/dt, b, d, r?

Adaptations to Desert Environments

Selection Thinking

The true power of the process of natural selection is that it provides us way of thinking about the diversity in the world around us. If we expect that organisms will be adapted to the condition in their environment the we can think like engineers and ask the questions- how would I design the a trait in that environment? We call this approach "selection thinking". This approach has been highly successful in allowing scientists to understand aspects of physiology, morphology, life history, and behavior in all sorts of environments in all sorts of species. In my research I have used this approach to study behavior in sparrows, woodrats, and beavers and reproduction in deer and plants.

Often, ecologists use mathematical models (often models ripped off from economists and engineers) as tools to help them understand traits of organisms. Although explicitly using mathematical models to study adaptations is probably too advanced for most middle school and high school science classes, I do think that it is important for you as teachers to know that math is an extremely important tool for scientists and be able to express that to your students as often as possible. It is unfortunate that math and science are usually taught as separate topics. As a Zoology Major at UCSB I took calculus during my Freshman year because that is what my advisor told me to do. During the final quarter of my senior year when in a graduate level Reproductive Ecology the professor used calculus to solve a problem that I had the "Oh, now I understand why I was supposed to learn all of that math!" moment.

Using mathematical models forces scientists to do very important things. First, we must clearly state our assumption. Second, it forces us to formailze out logic. When scientists don't use mathetical models they are often forced to rely upon what we call "arm waving" verbal arguments (you should be familiar with these arguments because we see them all of the time when we watch politicians on TV). Often, conclusions that seem reasonable based on verbal arguments actually are incorrect because they are based on either unrealistic assumptions or faulty logic.

I came across an example of a faulty verbal argument while I was working on my Ph.D. I was interested in understanding how parents should invest resources to their offspring, specifically, how big should plants make their seeds. This is a relatively simple problem to think about. When plants reproduce they should be selected to make as many surviving offspring as possible. The number of surviving offspring should be the product of the number of seeds produced and the probability that a seedling survives after it germinates. The number of seeds produced depends on seed size; you can make fewer larger seeds or more smaller seeds. Because the size of a seed is influenced by how many resources that seed contains, the probability that a seedling survives is positively correlated with the size of the seed. The original models predicted that fitness would be maximized if a maternal plant made all of here seeds exactly the same size. However, when you actually measure sizes of individual seeds (and I measured tens of thousands of seeds during my Ph. D.) you see that there is a lot of variation in the size of seeds produced by the same plant. The focus of my Ph.D. research was to try to figure out why plants produced seeds of different sizes.

Several years earlier a scientist named Dan Janzen (a very famous tropical biologist) had published a theory suggesting that producing different sized seeds was an adaptation. His theory was based on a "hand-waving" verbal arguement. In a class I took in graduate school I developed a model to try to see if Janzen's arguement really made sense. My model suggested that Janzen's conclusions were wrong because the verbal logic he used was faulty. My professor suggested that I tried to publish my model. While I was writing that paper, another professor from Orgegon published a matehmatical model that came up with the completely different conclusions than my model. When I compared our two models, I saw that his conclusions were based on an unrealistic assumption and when you used the correct assumption in his model we drew similar conclusions.

Selection Thinking in Arid Environments

Because the environmental conditions in arid environments are particualarly severe, deserts offer an interesting location to study adaptations to local environmental conditions. Hopefully, the readings will give you a broad exposure to how natural selection can mold physiology, morpology, reproduction, and behavior in arid environments.

Powerpoint Presentation

Click here to see a powerpoint presentation "Introduction to Desert Flora and Fauna"
http://www.slideshare.net/secret/pw2UrKumkR7KRT

Expected Learning Outcomes

At the end of this course a fully engaged student should be able to

- identify and discuss the unique challenges associated with living in arid environments (TEKS 112.43 12C)
- explain adaptations of animals and plants for water uptake and water conservation (TEKS 112.43. 7B)
- explain adaptations of animals and plants for dealing with high temperatures (TEKS 112.43. 7B
- develop curricular materials to teach students about adaptations to arid environments TEKS 112.43. 7B)
- develop curricular materials to teach how animals or plants are adapted to a different (non-desert) environment ((TEKS 112.43. 7B & 112.43.12B)

Practice Assignment

To test your understanding of how natural selection affects traits, I suggest that you try to develop a lesson to teach your students how the traits that you observe depends on the environmental conditions. In about one page, outline the lesson you would use to explain how and why the same trait varies between two very different environments. I suggest that you choose an adaptation to life in the desert and compare that train in an very different environment such as a tropical rainforest (much wetter) or the arctic (much colder). If you post your answers here I, and hopefully your classmates, will provide you some feedback.