Invasive Species

Invasive species are an important threat to biodiversity and can be very costly to humans.

Further Reading

1) Invasive Species- http://www.eoearth.org/article/Invasive_species

2) Marine Invasive species - http://www.eoearth.org/article/Marine_invasive_species

3) Aquatic Invasive Species- http://www.eoearth.org/article/Aquatic_invasive_species

4) Invasion Fact Sheet- http://www.eoearth.org/article/Invasion_fact_sheet

5) Invasive Species Slideshow- http://www.slideshare.net/secret/bL1TCLiLtoH5Np


Expected Learning Outcomes

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

- discuss threats caused by invasive species
- discuss strategies to exclude or eliminate invasive species
- discuss some invasive species in Texas
- discuss factors that allow species to invade new communities

Is this the coolest wildlife video ever? From Kruger National Park in South Africa

One of my former students sent me a link to this video. It seems like almost everything that we have talked about so far is going on in this video. The highlight of my biology life was visiting Kruger Park when I was about 13 (how sad to peak so young). I saw lots of amazing animals, but I didn't see anything like this. Enjoy! Make sure you watch all the way through- it just keeps getting better.

http://www.youtube.com/watch?v=LU8DDYz68kM

Community Ecology- The Portal Experiment

Here are some photos from the research site in Portal, Arizona. For more information about the research project at Portal you can look at their website at
http://portal.weecology.org/

Expected Learning Outcomes

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

- distinguish between direct and indirect, positive and negative effects
- describe the experiemental design that Dr. Brown and his colleagues used to study exploitative competition between desert rats and rodents
- discuss the "search the the missing indirect positive effect of rodents on ants" and how that dilema was solved
-discuss why and how the outcome of studies of interactions betwen organisms can vary over time
- discuss the way that the ecological community responded when they learned the importance of long term studies
- discuss how indirect interactions influence my facvorite phrase "the world is complicated"

Community Ecology

Suggested Readings

Community Ecology- http://www.eoearth.org/article/Community_ecology

Competition- http://www.eoearth.org/article/Competition

Interspecific Competition- http://www.eoearth.org/article/Interspecific_competition

Exploitative Competition- http://www.eoearth.org/article/Exploitative_competition

Predation- http://www.eoearth.org/article/Predation

Mutualism- http://www.eoearth.org/article/Mutualism

Expected Learning Outcomes

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

- define competition, exploitative competition and interference competition

- identify and explain examples of exploitative and interference competition from a variety of environments

- define predation (narrow and broad sense), herbivory, and parasitms

- identify and explain examples of predation, herbivory, and parasitism from a variety of environments

- identify examples of morphological and behavioral adaptations that animals have to help capture their food

- identify examples of morphological, biochemical, or behavioral adaptations that animals have to protect them from predators

- identify and explain examples of mutualisms from a variety of habitats

Writing Assignment #2: Human Population Growth

As you have probably figured out by now, I think that human population growth is one of the most interesting and most important topics that we will cover this semester. I am pleased the the rest of the scientific community shares my views. The July 29th edition of Science magazine (one of the most respected and influential scientific journals in the world) contains a special section on Population. This section contains 9 news articles and 8 review and analysis papers. You can find all of these articles online at http://www.sciencemag.org/site/special/population

Your Assignment: 1. Over the weekend take a look at this special section and choose three of these papers. 2. Read these papers carefully. 3. In your informal notes, summarize each of these articles. Be perpared to briefly discuss the paper you read. 4. For each paper prepare three questions that you think might generate some discussion in class. Be prepared to ask a question and lead any follow up discussion.

On Monday we will hold a class discussion on these articles. Be prepared to participate both as a participant and as a discussion leader.

Writing Assignment

For this assignment I would like you to choose an audience (parents or other family members, a friend or a group of friends, co-workers. fellow classmates, a ex or current teacher, readers of the Lubbock Avalanche Journal, random people that you meet in the mall, etc.) and then explain your views on human population growth.

These papers should have three parts.

1. A short paragraph describing the audience you have chosen to write for. Provide some background about their currrent knowledge and attitude about the topic and why you chose to communicate to this audience.

2. The main body of the paper where you should explain your views of human population growth to your audience.

3. References that you used to develop your ideas.

Length: The first two sections should be limited to a maximum of three double spaced pages. I suggest that you use Times New Roman 12 point font and normal margins. You may include your references on a separate page.

Rough draft of the papers are due next Friday and we will workshop the papers on Monday.

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 capita birth rates or increase in per capita 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 Problem?

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

Here is a link to the article "Human Population Explostion" from the EoE.
http://www.eoearth.org/article/Human_population_explosion

7th Billion Person- http://www.thehindu.com/sci-tech/science/article2412108.ece

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

This link contains lots of interesting data- take a look

http://www.worldometers.info/

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.

Population Ecology- 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 I am talking about in BIOL 1404. You can take an Advanced Population Biology course if you want to learn more about how to apply these models to the "real real world".

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

Expected Learning Outcomes

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

- define the carrying capacity
- draw, and interpret the following graphs associated with logistic growth
-how population size changes over time in logistic growth when the initial population size is much smaller than the carrying capacity
-how the population size changes over time in logistic growth when the initial population size is much larger than the carrying capacity
-how population growth rate changes over time in logistic growth when the initial population size is much smaller than the carrying capacity
-how the population growth rate changes over time in logistic growth when the initial population size is much larger than the carrying capacity
-how the per capita growth rate varies over time in logistic growth
-how the population growth rate varies over time in logistic growth

- discuss the causes for the shape of the s-curve (this answer will need to include a discussion of both math and biology)

- discuss the factors that regulate population size, be able to distinguish between density dependent and density independent factors that regulate population growth and give examples

Population Ecology- Exponential Growth

From our earlier lessons 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
(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/Exponential_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 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, 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?

Readings


Population- http://www.eoearth.org/article/Population

Population ecology- http://www.eoearth.org/article/Population_ecology

Population growth rate- http://www.eoearth.org/article/Population_growth_rate

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


Expected Learning Outomes

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

- define and calculate the value of basic population ecology parameters

- draw and interpret the following graphs

a) how population size changes over time in exponential growth

b) how population size changes over time in logistic growth

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

- define and explain the carrying capacity

- discuss the factors that regulate population size, be able to distinguish between density dependent and density independent factors that regulate population growth and give examples

Writing Assignment #1

The web post "Adaptations to desert environments" on this site examines how natural selection has molded the morphology, physiology, and behvior of organisms living in arid environments.

Writing Assignment #1

Imagine that you have been assigned the job of developing material that can be used in the visitors center of a desert nature park. The purpose of this information is to teach park visitors about the organisms that live in deserts. You should think of your audience as being reasonably intelligent non-scientists (e.g., your roommate, your grandma, etc). Make sure that your material addresses the following points.

1) identify and discus the unique challenges associated with living in arid environments

2) explain adaptations of animals and plants for water uptake and water conservation

3) explain adaptations of animals and plants for dealing with high temperatures

Format: Maximum length is three pages. Use Times New Roman 12 point font, black color. You should put your name, date, and the title of your essay at the top of the page (there is no need for a "cover sheet".)

Due: First Draft Due Friday September 9th. Bring 3 copies of the paper with you to class on Friday (make sure you have a STAPLER and staple the pages together)! One copy will be for me and two copies will be for the other members of your "workshop" group. We will workshop the papers in class on Monday and the final paper will be due on Friday September 16th. Please make sure all work is turned in on time!!

Adaptations to Desert 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

Readings

Adaptations of desert birds and mammals http://www.eoearth.org/article/Adaptations_of_desert_birds_and_mammals

Adaptations of desert reptiles and apmphibians
http://www.eoearth.org/article/Adaptations_of_desert_amphibians_and_reptiles

Adaptations of desert plants
http://www.eoearth.org/article/Adaptations_of_desert_plants

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

- explain adaptations of animals and plants for water uptake and water conservation

- explain adaptations of animals and plants for dealing with high temperatures

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-

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