Fun With Graphs- Exponential Growth

Take a look at this before Monday as well.

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. Id 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 that relate to exponential growth.

http://www.slideshare.net/secret/mavlOD8flFs67G

NOTE:

Any graphs that contain the incorrect axes will be considered to be completely wrong on all exams and assignments!!

Population Biology 2. Exponential Growth

We may start examining this material on Monday Feb 2nd so please look it over before then.

Lecture Video- http://mediacast.ttu.edu/Mediasite/Play/b8c64d66f62a4747b7983398113f0b391d?catalog=4dc7289a-d3e0-4ae5-8fdc-5b86c027a06b


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 then take a look at the blog post entitled "How Did I Know What the Exponential Growth Curve Looked Like?".

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
(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 describe 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.

Suggested Readings

Here are some articles you should look at from the Encyclopedia of the Earth. I wrote these so they are brilliant!!!

Population Ecology http://www.eoearth.org/article/Population_ecology

Exponential Growth http://www.eoearth.org/article/Exponential_growth

Logistic Growth http://www.eoearth.org/article/Logistic_growth

Carrying Capacity http://www.eoearth.org/article/Carrying_capacity

Intraspecific Competition http://www.eoearth.org/article/Intraspecific_competition

Powerpoint Presentation

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

Expected Learning Outcomes

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

- draw and interpret the following graphs associate with exponential growth

a) how population size change over time in exponential growth

b) how population growth rate varies over time in exponential growth

c) how the population growth rate depends on the population size

d) how per capita growth rate changes over time in exponential growth

e) how per capita growth rate depends on population size

- explain why exponential growth is an unrealistic pattern of growth for most species

- define and explain the carrying capacity

Population Biology. 1. Basic Parameters

We may have time to start this topic on Monday February 2nd so it would help if you take a look at this before then.

Lecture Video: http://mediacast.ttu.edu/Mediasite/Play/20ade8c97b0b40af8eaab29ae07eee6f1d?catalog=4dc7289a-d3e0-4ae5-8fdc-5b86c027a06b

IMPORTANT NOTE!!!
For the next several lectures we will be using math and graphs to help us explore population ecology. From my experience teaching this topic in the past, many of you will experience some difficulties with this material because you are not confident when dealing with math and graphs.

Rather than introducing the concepts to you in lecture and then having you work on activities to help you master the material out of class, this year I would like to "flip the class". This year I would like for you to study the material before coming to class so that we can use the class time to answer your questions and to help you master the material.

Assignment- Before Wed December 30th, I expect that you will have read the following post and are able to meet all of the expected learning outcomes listed below. If you have not mastered the material in this blog, then you will find that you will be hopelessly lost in the lectures that follow!!

Expected Learning Outcomes

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

- define b, d, r, B, D, dN/dt.

- identify and use the proper units associated with each parameter

- use the correct algebraic equations to calculate each of these parameters

- be equally comfortable referring to these concepts verbally or via their algebraic symbols.

Basic Parameters of Population Ecology

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 (5) 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 of elephants, there are 100 individuals.

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

1. 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?

2. List the equation/equations for calculating the following parameters
a) b
b) the population growth rate
c) r

Sexual Selection

This is the material that we will discuss on Monday February 2nd.

Lecture Videos to Watch- http://mediacast.ttu.edu/Mediasite/Play/46946a59e6fe4dfda9dcec19246d2acf1d?catalog=4dc7289a-d3e0-4ae5-8fdc-5b86c027a06b

I think that sexual selection is one of the most interesting topics in all of biology. First, studying this topic helps to illustrate that natural selection is much more than "survival of the fittest". Second, many of the traits produced by sexual selection are particularly weird and wonderful. Finally, I think that it is fun to use what we have learned about mate choice in animals to helping us to understand human behavior.

Expected Learning Outcomes

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

- discuss the critical difference between males and females and discuss how this difference influences differences in behavior and morphology between species.

- discuss why sexual selection is just a subset of natural selection

- discus why females should be choosier about who they mate with than males

- discuss why males often compete with other males to fertilize eggs of females

- compare and contrast male-male competition in species with internal fertilization and species with external fertilization

- describe the studies used by scientists to see if females are capable of choosing the best males

- discuss how females can determine which is the best male

- discuss why the variation in female reproductive success is much less than the variation in male reproductive success

- discuss how you would use sexual selection to help you understand human behavior

Past Exam Questions (answers at the bottom of the post)

1. Why are females choosier than males about who they mate with?
(a) female gametes are much more expensive than male gametes
(b) male gametes are much more expensive than female gametes
(c) in some species, males are larger than females
(d) in some species, males compete to mate with the female
(e) c and d

2. Why should females prefer to mate with the oldest males?
(a) because they can pass on good mating genes to their daughters
(b) because they can pass on good survival genes to their sons
(c) because the can pass on good survival genes to their daughters
(d) a and c
(e) b and c

3. Why might females sometimes cause male-male competition to occur?
(a) to assure that she mates with the oldest male
(b) to assure that she mates with the most symmetric male
(c) the male who wins the fight is likely to have “good genes”

(d) a and c

(e) a, b, and c

Further Reading

Here is a link to a website that a student sent to me  called "The 30 Strangest Animal Mating Habits" http://www.neatorama.com/2007/04/30/30-strangest-animal-mating-habits/

Take a look at this and see if you can relate what the animals are doing to some of the theories that we have talked about in class.

Here is a link to a youtube video showing the mating display of lyrebirds. I was lucky enough to see a lyrebird doing its mating display when I was a kid living in Australia. There was a professional nature photographer who had been hiking around the bush for a couple of weeks waiting to see the display and he was pissed that my Dad and I were able to see the display after spending only about an hour in the woods. What do you think is going on with the lyrebirds?

http://www.youtube.com/watch?v=VjE0Kdfos4Y

Here is a link to the Powerpoint Presentation I prepared for this topic.

http://www.slideshare.net/secret/CG2HHvtrLA1KwL

Answers. 1. a, 2. e, 3. c

Here is a link to an interesting article that I  discovered on an ex-student's Facebook page. Biology is Cool!!!!!

Male spider snaps off own genitals inside female to fertilise her remotely, while being eaten.

http://blogs.discovermagazine.com/notrocketscience/2012/02/01/male-spider-snaps-off-own-genitals-inside-female-to-fertilise-her-remotely-while-being-eaten/

The Evolution of Antibiotic Resistance

I think that the evolution of antibiotic resistance is an interesting and important issue. Below I has listed the expected learning outcomes for this topic in BIOL 1404. Because this topic has widespread medical relevance I have included a lot of additional readings and a powerpoint presentation that I developed for another class last semester. This info is not required, but is only intended to provide more info to interested students.

Expected Learning Outcomes

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

- discuss the causes of the development of antibiotic resistance

- discuss what we have learned from ecology and evolutionary biology about potentila problems associated with antibiotic use

- discuss what we have learned from evolutionary biology that should help us fight microbial diseases more effectively

Past Exam Questions (answers at the bottom of the post)

In the 1950s, Japanese physicians began to notice that some hospital patients suffering from bacterial dysentery, which produces severe diarrhea, did not respond to antibiotics that had generally been effective in the past.

1. In order for the result described above to have occurred, which of the following must have been true in the population of dysentery-causing bacteria?
(a) there was variation in the susceptibility of the bacteria to antibiotics
(b) antibiotic resistance was heritable
(c) bacteria that were more resistant to antibiotics had higher survival rates than less resistant bacteria
(d) a, b, and c
(e) neither a, b, or c was true


2. What can be done in future to limit the problem of antibiotic resistance in disease-causing microorganisms?
(a) Doctors should only describe antibiotics when appropriate
(b) Doctors should prescribe larger doses of antibiotics
(c) patients should make sure to take all of the pills when antibiotics are prescribed
(d) a and c
(d) a, b, and c

Answers 1. d 2. d

Further Reading

Evolution of Antibiotic Resistance-
http://www.pbs.org/wgbh/evolution/library/10/4/l_104_03.html

Antibiotic resistance: Questions and Answers- CDC
http://www.cdc.gov/getsmart/antibiotic-use/anitbiotic-resistance-faqs.html

Antibiotic resistance- delaying the inevitable (parts 1 and 2) UC Berkeley
http://evolution.berkeley.edu/evosite/relevance/IA1antibiotics2.shtml

HIV the ultimate evolver (parts 1-3) UC Berkeley
http://evolution.berkeley.edu/evosite/relevance/IA2HIV.shtml


When Penicillin Pays: Why China Loves Antibiotics a Little Too Much http://www.time.com/time/world/article/0,8599,2103733,00.html

Here is a link to an article about India I just discovered.
The Super-Resistant Bacteria That Has India 'Hell Scared' http://www.theatlantic.com/international/archive/2012/01/the-super-resistant-bacteria-that-has-india-hell-scared/251731/

Here is an link to an article about what is going on in the US sent to my by a fellow BIOL 1404 students. Thanks!
Antibiotic-Resistant Bacteria Found in 37 U.S. States
http://news.yahoo.com/antibiotic-resistant-bacteria-found-37-u-states-204438989.html

Powerpoint Presentation

Here is a link the the powerpoint presentation I used in another class.

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

The Evolution of Sex

Lecture Video to Watch- http://mediacast.ttu.edu/Mediasite/Play/e42a326764d74e86b6f290c258365a6b1d?catalog=4dc7289a-d3e0-4ae5-8fdc-5b86c027a06b

Based on our understanding of natural selection, at first glance sexual reproduction doesn't appear to be advantageous from the female perspective (due to the two-fold cost of sex). However, the fact that sexual reproduction is so common in all groups of organisms suggests that there must be some major benefits of sex that outweight the costs.

Expected Learning Outcomes

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

- explain "the two-fold costs of sex"
- discuss possible benefits of sexual reproduction including adaptation to environmental uncertainty and fighting disease
- be able to discuss the problem of the evolution of antiobiotic resistant microbes
- be able to discuss what the medical field may be able to learn from observing how nature fights disease.

The Honors Section Exam will not contain multiple choice questions but you can quiz yourself by looking at these.

Past Exam Question (answer at the bottom of the post)

1. What is the “two fold cost of sex”?
(a) female gametes are twice as expensive to produce as male gametes
(b) the genetic variation produced by sexually reproducing females provides a benefit if there is environmental uncertainty
(c) individuals reproducing asexually pass on twice as many of their genes
(d) a and b
(e) b and c

2. Which of the following hypotheses can explain a benefit of sex?
(a) males pass on more genes in sexual reproduction than in asexual reproduction
(b) the genetic variation produced by sexual reproductions provides a benefit in uncertain environments
(c) females reproducing asexually pass on twice as many of their genes
(d) a and b
(e) b and c


Further Readings

Although I am usually a little skeptical of articles form Wikipedia, this one is pretty good. It goes into more detail than you need to know, but provides some useful information

Evolution of Sexual Reproduction http://en.wikipedia.org/wiki/Evolution_of_sex

Interesting Article by Evolutionary Biologist David Barash

The Good News About Sex http://chronicle.com/blogs/brainstorm/the-good-news-about-sex/43292

Life in Local Playa Lakes

If you would like to learn a little more about local playa lakes-

Playa Lakes http://www.eoearth.org/article/Playa_lake

Drawings of cladocerans similar to those inhabiting playa lakes.










This is what they don't look like.

answer- 1. c 2. b

Cultural Selection

In humans there are examples of alturistic behaviors that appear to be difficult to explain by kin selection of reciprocal altruism (e.g. soldiers sacrificing their lives in battle, police or firefighters risking their lives, catholic priests remaining celibate).

Genes are self replicating molecules. Genes produce our bodies which in turn produce more copies of their genes. Richard Dawkins has suggested that we think about genes as being "replicators" and our bodies as being "vehicles" whose job it is to make more copies of the replicators. If we can not explain altruistic behaviors as strategy for increasing the transmission of genes into the next generation them maybe we need to search for another kind of "replicator". Dawkins has suggested that "ideas" (he calls them "memes") are also capable of self replication. Because ideas differ in how long they survive and how well they are passed on it should be possible to have selection for ideas (cultural selection).

Expected Learning Outcomes

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

- identify examples of altruistic behavior that might be explained by cultural selection
- be able to compare and contrast "natural selection" with "cultural selection"

Further Readings

Cultural evolution http://plato.stanford.edu/entries/evolution-cultural/

As I mentioned in class, one of my favorite books of all time is "The Selfish Gene" by Richard Dawkings. He discusses some of his ideas about cultural selection in the final chapter of this book. Here is a link to that chapter in case you are interested
http://www.rubinghscience.org/memetics/dawkinsmemes.html

Reciprocal Altruism

Altruistic acts among non relatives can be understood by reciprocal altruism. As we discussed in class we would expect reciprocal altruism to be limited to species that show long term associations and are "smart" emough to be able to recognize individuals and remember who owes them and who does not.

Examples of Past Test Questions (answers at the bottom of this post)

1. It is not uncommon for college students to share items such as shampoo with their roommates. Which of the following hypothesis best explains this behavior?
(a) group selection
(b) kin selection
(c) reciprocal altruism
(d) selfish behavior
(e) altruistic behavior

2. Which of the following terms apply to a roommate who borrows your shampoo when she/he has run out, but will not allow you to borrow their shampoo when you need it?
(a) altruistic
(b) mutualist
(c) cheater
(d) a and c
(e) b and c



Further Readings

Reciprocal Altruism http://www.bbc.co.uk/nature/animals/mammals/explore/altruism.shtml

Reciprocal Altruism in Vampire Bats http://www.bio.davidson.edu/people/vecase/behavior/Spring2002/Perry/altruism.html

If you are interested in learning more about Evolutionary Psychology here is a link to a bunch of Frequently asked questions. Some of this goes into way more detail than we need to be worried about for this class.
FAQ Evolutionary Psychology http://www.anth.ucsb.edu/projects/human/evpsychfaq.html

Expected Learning Outcomes

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

- define reciprocal altruism
- discuss the conditions under which altruistic acts can be explained by reciprocal altruism
- examine an example of an altruistic behavior and determine whether reciprocal altruism is the best explanation
- explain how participants benefit by being involved in reciprodal altruism in real world examples (e.g, vampire bats)
- define a cheater in a reciprocal altruism system and discuss (a) why cheating is a problem in the system and (b) what organisms can do to reduce cheating
- discuss Trivers' ideas about how human psychology has been influenced by reciprocal altruism (be able to provide your opinion about Trivers' ideas and be able to back up your opinions)


Answers 1. c even though this is an example of altruistic behavior, the best explanation for this behavior is reciprocal altruism) 2. c

More Fun With Altruism

Question to Think About

Some birds have a behavior known as "helping at the nest". A female bird will sometimes help another bird rear offspring rather than laying her own eggs and raising them. There are two different hypothese to explain this behavior. First, this may be an example of an altruistic behavior that can be explained by kin selection. Alternatively, this may be an example of a purely selfish behavior. It is possible that young inexperienced birds are not very good at raising offspring the first time they try and by helping another bird to raise offspring they may get practice that makes them better at rearing offspring later on.

1) Explain how you as a scientist would conduct a study to distinguish between these two alternative hypothese.

2) Should a female bird who is capable of raising three offspring on her own help her sister to raise her sister's offspring if helping her sister allows her sister to raise five more offspring? Be sure that you would be able to explain to someone else how you determined your answer.

If you post your answers to the blog then I will be able to take a look at them and you can also get some feedback from fellow students.

Old Exam Questions

Here are some examples of old exam questions dealing with altruism. See if you can figure out the correct answers (answers provided at the bottom of this post).

Researchers studying black-tailed prairie dogs conducted an experiment where they dragged a stuffed badger (a predator of prairie dogs) across the colony. They repeated the experiment 698 times over the course of 3 years. The researchers observed that individuals with no offspring in the colony gave a warning call 19% of the time whereas individuals with offspring in the colony called almost 50% of the time. Which of the following could explain why individuals with no offspring would ever call?
(a) group selection
(b) other squirrels will return the favor in the future
(c) they have other relatives in the colony
(d) a and b
(e) a, b, or c would explain this observation


Which of the following are examples of an altruistic trait?
(a) an African wild dog sharing food with other members of the group
(b) a female choosing to mate with a symmetric male
(c) a sterile worker bee helping her sister (the queen) to reproduce
(d) a and c
(e) neither a, b, or c


Further Reading

Here are links to a couple of articles you might want ot take a look at-

Altruistic behaviors http://www.eoearth.org/article/Altruistic_behaviors

Kin selection http://www.eoearth.org/article/Kin_selection

More advanced reading

One of the problems with introductory courses is that we have to cover so many topics that it is not possible to go into very much detail over any of them. If you are interested in learning more about kin selection and altruism the following article would be good to look at.

Kin selection: fact and fiction. http://westgroup.biology.ed.ac.uk/pdf/Griffin&West_02.pdf

Why Group Selection Does Not Work

Photo: Large flock of European Starlings (a bird)




Group selection is the hypothesis that organisms have the traits they do (including altruistic traits) because selection has produced traits that assure that species survive. Although this is intuitively an OK idea, it turns out that it doesn't work.

Have you ever noticed large "roosts" of birds in trees around town. Roosting birds gather by the hundreds or thousands in one, or a few, trees (maybe you have mistakenly parked you car underneath a roost and suffered the consequences). Biologists are interested in understanding the causes of roosting behavior. People who support the group selection hypothesis have proposed that the reason that these birds are roosting is that it gives them an opportunity to examine how large their population is. Becasue the birds do not want to overpopulate their environment, because overpopulation could lead to a loss of all of the food so that the entire species dies, birds want to know how many other birds are there so they know how much to reproduce. If birds see that the roosts are large then they know that the population is large so they decide to produce only a few babies. However, if the birds see that the roost is small then they are decide to produce many babies. Thus, the population never gets so large that they eat up all of the food.

Unfortunately, the math required for group selection just doesn't work out. Imagine a species of birds that mated monogamously for life. If the parents wanted to keep population sizes constant than their best strategy would be to produce two offspring during their life so that they make just enough kids to replace themselves. For this to happen all females would have a gene that said "make two babies". Imagine that a mutation occurs that says "make three babies". This mutation would quickly spread througout the population so that eventually all females would produce babies.  If mutations that said produce 4 or more babies occurred then these mutations would also spread. It is thus possible to imagine that each female would make so many babies that the population would indeed get large enough to consume all of the food which would cause the population to go extinct.  Thus, the math of natural selection does not allow organisms to artificially reduce their fitness for the "good of the species".

The observation that led group selectionist to thinking that roosting and reproduction could be explained by group selection was that females produced fewer eggs when more individuals were at the roost than when fewer individuals were at the roost. Can you think of another hypothesis to explain this observation?

So why do birds form roosts? There are at least two hypotheses. First, some scientists propose that organisms roost because they are safer from predators when living in large groups. Others think that organisms form roosts because they can benefit from information gained by living with lots of other individuals. For example, if you flew to the south to look for food and didn't find much and you noticed that those birds returning to the roost from the north looked well fed, then you might head out to the north the next day.

Expected Learning Outcome

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

- discuss why the classic notion of group selection does not work in nature

Altruism part 1

Lecture Video to Watch


http://mediacast.ttu.edu/Mediasite/Play/63042145bb50446dbff54ad0f1d7c7611d?catalog=4dc7289a-d3e0-4ae5-8fdc-5b86c027a06b


From our discussion about natural selection you should have learned that organisms have the traits they do because traits that produce phenotypes that are more successful at transmitting genes to the next generation (surviving and reproducing) become more common in a population over time. Thus, we expect organisms to have traits that maximize their individual survival and reproduction (we call these selfish traits).



Examples of Altruistic Behaviors



1. Broken wing display by kildeer
kildeer live around here so you should be able to see this behavior later on this spring (that will require going outside!)

http://www.youtube.com/watch?v=TNG7y0caqj0



2. Group defense in musk oxen
you can't see this around here even if you go outside.

http://www.youtube.com/watch?v=pb6Rke7jiTc



3. Food sharing in African Wild Dogs

http://www.sandiegozoo.org/animalbytes/t-wild_dog.html



4. Prairie dogs giving warning calls

http://www.youtube.com/watch?v=rXCPaNWcTFo



We should originally be a little bit confused when we learn about altruistic traits. How can genes that produce traits that decrease an organisms abilty to survive or reproduce become more common in a population?!? Luckily, we have learned that understanding what happens in natural selection requires us to focus on the transmission of genes. Apparently, organisms that behave altruistically are actually passing on more genes by behaving altruistically than they would by behaving selfishly.  How can this be? (this problem perplexed Darwin).



Fortunately, a lot of really smart scientists have thought about altruism and have recognized that their are a variety of different ways that organisms behaving altruistically could pass on more genes than organisms acting selfishly. There are at least 4 different hypotheses that can explain the evolution of altruistic behaviors (one of these will probably only help to explain altruism in humans).

The first explanation for why organisms were altruistic was the idea of group selection. Group selection is the idea that organisms have traits becasue those traits "assure the survival of the species". At first glance this seems like a pretty useful idea, but it actually does not work and it has been a very difficult idea to remove from the minds of the general public even though scientists have know that it is wrong and unecessary (there are much better theories about the causes of altruism) for over forty years. It would take a while for me to explain why group selection doesn't work so I won't spend any more time talking about it either in class or here on the blog. However, if you are interested in learning more about this I would be happy to chat with you.



It is important for this class that you are able to understand under which conditions the other hypotheses could explain the presence of altruistic behaviors.



Hamilton's Rule



Hamilton's Rule is a mathematical equation that helps scientists understand under which conditions organisms should behave altruistically and when they should behave selfishly. It is important that you understand (1) how sceintists use mathematical models to help us understand the world and (2) what Hamilton's Rule tells us about when organisms should behave altruistically.



Suggested Readings

Biological Altruism- http://plato.stanford.edu/entries/altruism-biological/



Expected Learming Outcomes



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

1) define altruistic traits and provide several examples

2) compare and contrast selfish traits and altruistic traits

3) explain why altruistic traits at first glance appear to be difficult to understand based on what we know about the process of natural selection

4) discuss at least four possible hypotheses that explain the presence of altruistic traits and explain under which circumstances these theories are expected to apply

5) use “Hamilton’s Rule” as an example to illustrate how biologists use mathematical models to help them understand biology

6) discuss how Sherman’s work with Belding’s Ground Squirrels provided support for Hamilton’s Rule

7) be able to determine which hypothesis best helps you understand any examples of altruistic traits that I give you and be able to justify that answer

Patterns of Selection

As I mentioned in the natural selection expected learning outcomes, I want you to understand the three patters on selection- directional selection, stabilizing selection, and disruptive selection. In addition, to the readings in your textbook, you will find useful info on this topic in the Encyclopedia of the Earth article on Evolution http://www.eoearth.org/article/Evolution.

Expected Learning Outcomes

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

- distinguish between directional, stabilizing, and disruptive selection
- describes how directional. stabilizing, and disruptive selection work
- give examples of traits produced by each of these patterns of selection
- draw the graph that shows the relationship between fitness and trait size that produces each of these patterns of selection.

Natural Selection

An understanding of the process of natural selection helps us to understand the amazing diversity of life on the earth.

Expected Learning Outcomes

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

1) define the process of natural selection

2) distinguish between the patterns of stabilizing, disruptive, and directional selection and provide examples of each pattern

3) describe how the process of natural selection has produced a trait that is an adaptation to a particular environmental condition.

4) explain why organisms are not expected to be perfectly adapted to their environments

5) discuss the conditions that would cause natural selection to stop

6) explain why natural selection is expected to produce selfish traits

Readings

Natural selection http://www.eoearth.org/article/Natural_selection

Here is a link to a website from UC Berkeley that might be useful to take a look at-

http://evolution.berkeley.edu/evolibrary/article/evo_25

The Mark McGinley Story

Here is the perfect cure for insomnia!


The Formative Years

I was born in Corpus Christi, TX and after a couple of moves we ended up in Rosenberg, (near Houston) where I attended grade school. I was interested in biology from an early age; I watched Marlin Perkins and Jacque Cousteau (your parents should know who they are) and I spent a lot of time outdoors on family camping and fishing trips. Even though I grew up near Houston during the Apollo years, I always thought that it would be much cooler to be a biologist than an astronaut.

When I was in the sixth grade my family moved to Australia for four years. This was an amazing life change for a kid who thought that the annual trip to my grandparents’ house in Oklahoma was a big deal. I had the incomparable experience of living in another country and experiencing a whole new way of life. Probably the biggest difference between Australia and the U.S. was the schools. I went to an all-boys English-style, private school where we had to wear uniforms (suits and ties) and straw boater hats to class everyday (this probably explains my preferred style of dress today).

The move also provided me with the opportunity to travel the world. During trips through Europe and Asia we saw many places of historical and cultural interest. Among my favorites were the Coliseum in Rome, the Tower of London, and Mt. Fuji in Japan. More importantly, my travels exposed me to many new biological experiences including seeing hippos, gazelles, elephants, and a cheetah in South Africa, snorkeling and  beach combing in Hawaii, Tahiti, Fiji, and the Great Barrier Reef, chasing emus through the Australian outback, watching a male lyrebird do his mating dance, watching fairy penguins come ashore for the night off of the coast of southern Australia, and many sightings of other Australian wildlife including kangaroos and koalas (how many people do you know that have ever seen a koala running along the ground?).

During the summer before my sophomore year in high school we moved to Thousand Oaks, CA (old-timers will remember TO as the former summer home of the Dallas Cowboys before they were ruined by Jerry Jones) where I graduated from high school. During my senior year I spent a week studying ecology and philosophy in Yosemite National Park and this trip confirmed by desire to be a biologist.



Education



I enrolled at the University of California, Santa Barbara to study biology. UCSB is an incredible place to go to school (I could see the ocean from my bedroom window three out of the four years that I was there) and it also happened to have one of the best ecology programs in the world. Joe Connell (one of the most influential ecologist of our era) taught the ecology section of my intro biology course and also taught my first ecology course, so it is probably his fault that I am here today because after finishing his course I knew that I wanted to be an ecologist. Later, after taking courses from Steve Rothstein and Bob Warner, I became interested in behavioral and evolutionary ecology and I decided to go to grad school to study behavioral ecology. I went to Kansas State University in Manhattan, KS which was a pretty big change from UCSB. I enjoyed K-State (I learned to bleed purple for Wildcat basketball) and I was lucky to be able to spend summers working for my advisor Chris Smith at the Mountain Research Station in Colorado studying pollination in lodgepole pine. My Masters Thesis extended optimal foraging models to examine woodrats foraging for non-food items (sticks that they use to build their houses). I also did a theoretical study examining how food stress should affect sex ratios. I earned a Ph. D. at the University in Salt Lake City. For my Ph. D. thesis with Jon Seger, I developed models and conducted experiments to understand the causes of seed size variation in plants. During my little free time, I played volleyball with the U of U Volleyball Club team and I was probably the only person in the whole city who did not ski (I still don’t see the point of intentionally getting cold). I spent two years working as a post-doctoral researcher with Dave Tilman at the University of Minnesota. Our research focused on succession in old fields at Cedar Creek Natural History Area just north of Minneapolis.


Life at Texas Tech

I started as an Assistant Professor in the Department of Biological Sciences at Texas Tech University in 1991. I am currently an Associate Professor with a joint position in the Honors College and the Department of Biological Sciences. In the Honors College I work closely with the Environment and the Humanities degree. (http://www.depts.ttu.edu/honors/evhm/).  Last year I was appointed as an Assistant Dean in the Honors College.


Teaching


I teach a wide variety of classes at Tech. Two of my favorite courses are Tropical Marine Biology (taught in Jamaica and Belize) and the Rio Grande Class (we take a week-long canoe trip through Big Bend over Spring Break). For the past 6 summers I have worked as a scuba instructor and marine biologist with Odyssey Expeditions leading sailing and scuba trips through the Caribbean (British Virgin Islands, Martinique, St. Lucia, and St. Vincent & the Grenadines).



Scholarship

For several years I conducted ecological research in the sand shinnery oak community in West Texas. My current interests are in science curriculum development, environmental education, and informal science education. I am currently the Editor-in-Chief of the Encyclopedia of the Earth (http://www.eoearth.org/) an online source of information about the environment.



Fulbright in Malaysia



I spent the 2010-2011 academic year as a Fulbright Visiting Scholar at the University of Malaya in Kuala Lumpur, Malaysia. In addition to teaching a class at the UM, I was able to travel throughout the Malaysia and other parts of SE Asia (Thailand and Cambodia). In enjoyed exploring the rainforests and islands of Malaysia.  Some of the coolest things I saw were a sea turtle laying eggs, Orangutans, and a Borneo Pygmy Elephant. To learn more about my adventures in Malaysia you can check out my blog. http://markinmalaysia.blogspot.com/



Traveling

I enjoy traveling and I have been able to explore my passion for scuba diving on dive trips in Texas (San Solomon Springs in Balmorhea and the Flower Garden Banks) throughout the Caribbean as well as Yap, Palau, Solomon Islands, Fiji, Malaysia, Indonesia, and Galapagos Islands. My favorite marine critters include hammerhead sharks, pygmy sea horses, and “the pea”. Over the holidays I visited the Philippines, Malaysia, Thailand, Vietnam, and Cambodia.

Here I am giving the "guns up" with a girl from the Kayan tribe in NW Thailand.  The Kayans are sometimes known as the "long-necks" because the women wear brass rings on their necks to make it appear that their necks are longer.