1. Based on cues in the environment, organisms change their behavior and physiology.
2. Communication between organisms in response to internal or external changes can change behavior.
3. Signaling changes the behavior of other organisms and is subject to natural selection.
4. A variety of signals (visual, auditory, tactile, chemical, and electrical) are used to indicate social dominance, find food, and induce or solicit mating.
5. Learned and innate behaviors are subject to natural selection.
6. Cooperation between members of the same population can increase fitness.

So, what I chose to do on Learn-Biology.com is to focus on some important biological literacy goals that will also help our students as we get them ready for the AP Bio exam. We want our students to be able to explain 1) how animal behavior can be elicited in response to environmental cues, 2) how animals communicate with one another, and  3) how animal behavior is optimized by natural selection. And, on top of that, being able to analyze sets of data and diagrams related to animal behavior is something that shows up pretty frequently on the AP Bio exam.

Holding all that in mind, here’s what I came up with. There’s a strong emphasis on case study analysis.

Teaching about Responses to the Environment on s Learn-Biology.com

Our module on animal behavior covers this material in four tutorials. You can find the main menu on this page.

Fixed Action Patterns and Behavior Genes

Learning and Orienting

In this tutorial, we move from hard-wired behaviors to ones that involve learning. The first of these is imprinting, first discovered (and hilariously manipulated) by Austrian zoologist Konrad Lorenz. This is followed by an analysis of much more complex learned behaviors: learning songs in songbirds, and navigation in wasps. The tutorial ends with an unbelievably cool study of how ants know how to make their way back to the nest after foraging. This is known as the ant odometer, and you don’t want to miss it.

Migrating

This tutorial examines the internal and external cues that animals use during migrations. In the first case study, we focus on how Indigo buntings navigate by learning how to follow the stars. In the second, we look at how sea turtle hatchlings are able to first find their way to the sea. Once the turtles make it out to sea, they face the challenge of long-distance migrations (that often span thousands of miles). To do that, they use magnetoreception and perception of geomagnetic signatures to find their way back to the beaches where they originally hatched. I found this to be mind-blowing when I first learned about it. My guess is that your students (and you) will feel the same.

Living in Groups

The module ends with a tutorial about group behavior and its biological basis. The first case study looks at alarm calls in Belding’s ground squirrels. Who do you think gives alarm calls first: males or females? Why would that be? What you’ll see this that this study is a great way to get into the concept of kin selection and inclusive fitness. This leads to a look at haplodiploidy in bees, and how that can explain the social structure of a bee hive. We end with a discussion of honey bee dances, and how bees use their dances to communicate about the direction and distance to food sources to other members of the hive.

Additional Resources

In the AP Biology Lab Manual, you can find the “Fruit Fly Behavior Lab” (investigation 12). I use a much simpler (and less expensive) version of this lab. My version involves pill bugs (Armadillium vulgare), which you or your students can probably find in any park (or backyard). If students collect 10 each, you’ll have more than enough. I have a set of choice chambers that I bought from Carolina biological supply, but you can have your students construct their own by cutting out the bottom of two milk cartons, cutting out a notch to make a pathway between them, and then scotch taping them together. Then just lay a paper towel that’s cut to size on the bottom of each carton and you’ll be set.

Here’s a link to my version of the lab. I’m sure it can be improved. And just to prove to myself that it could be done, I just spent about 10 minutes putting together a milk-carton choice chamber. Here’s a photo.

Learning objectives for Topic 8.2, Energy Flow through Ecosystems

Teaching about Energy Flow through Ecosystems on Learn-Biology.com

Topic 8.2 Part 1: Energy Use in Organisms

This tutorial starts by clarifying the ways that autotrophs, heterotrophs, and chemoautotrophs derive energy from the environment to sustain their life processes.

This leads to a general discussion of metabolic rate, and the way in which energy use scales with size, as shown in the graph below

That makes sense, right? You’d expect that the energy required to sustain an elephant would be much more than the energy required to sustain a smaller animal (like a pig) or a mouse.

But what’s fascinating is that as an animal’s mass increases, its metabolic rates/gram of tissue decreases. A gram of tissue in a shrew (the smallest mammal) is burning through energy a million times faster than a gram of elephant tissue does. When graphed, that relationship looks like this:

The reasons for this are largely (but not entirely) related to surface area: volume ratios and this topic will give you a great opportunity to do some review of topic 2.3 (Surface Area and life). For a deeper dive into this material, I strongly suggest that you read this archived article from the NY Times (from 1999: no subscription needed).

The tutorial ends with a discussion of metabolic differences between endotherms and ectotherms, and adaptations that occur in both groups related to optimizing energy use.

Topic 8.2, Part 2: Carbon Cycle

It’s hard to imagine teaching about ecosystems at the AP/Introductory college level without teaching about biogeochemical cycles. But the term “biogeochemical cycle” doesn’t appear anywhere in the 2019 Course and Exam Description. Nor does the term “carbon cycle.” Oversight? Hard to know. My first tutorial focuses on … the Carbon Cycle. It’s pretty easy, and I can’t imagine sending my students out into a world where the number 1 issue is climate change caused by disruption of the carbon cycle without them understanding the carbon cycle. I hope you feel the same way.

Topic 8.2, Part 3: Food Chains and Food Webs 

This tutorial will teach your students about autotrophs, heterotrophs, food chains, food webs, and the basics of trophic levels.

Topic 8.2, Part 4: Trophic Levels

This tutorial goes into depth about trophic levels and will take your students through energy pyramids and the 10% rule. Pyramids of numbers and biomass are also covered.

Additional Resources

As I said above, it’s not clear if the Carbon Cycle is part of the curriculum anymore. But if you teach it, I have a music video for you. I also have one about food chains. My Food Chains Song is one of the only songs I’ve written to someone else’s melody. It’s based on the Ballad of Jed Clampett, also known as the “Beverly Hillbillies Song.” Both songs are immensely singable (and playable on guitar). Here are the links.

1. Carbon Cycle
2. Food Chains Song

I can’t share the links for the next two items directly (because they’re copyrighted material) but the high school biology POGILS on “Energy Transfer in Living Organisms,” and “Ecological Pyramids are both excellent and highly recommended.

HHMI has a terrific video about how aquatic food webs in rivers can be studied. In addition, there’s an HHMI card-sort activity about modeling food webs in a tropical rainforest ecosystem.

NOTE: The material below has not yet been updated to reflect changes in Learn-Biology.com’s AP Bio v2.0 curriculum. 

Learning objectives for Topics 8.3-4 (Population Ecology) and 8.5 – 6 (Community Ecology and Biodiversity)

If you want to look at the College Board’s objectives for these topics, you can do so on my condensed outline (this link takes you to the Ecology unit: just scroll down). Or you can do the same at the College Board’s original pdf.

Here’s an outline of how I cover this material on Learn-Biology.com.

TOPICS 8.3 and 8.4, Population Ecology.

1. What is a population?
   1. Defining and describing populations
   2. How individuals in a population interact with each other and with their environment
2. Explain the general factors explaining population growth, and the general equation for this growth  (dN/dt = B – D)
3. Explain how exponential growth works (and its relevant equation: dN/dt = rmaxN
4. Explain how density can affect population growth by imposing limiting factors
   1. Density Dependent Limiting Factors
   2. Density Independent Limiting Factors
   3. Logistic Growth equation (dN/dt = rmaxN (K-N/K))

Topics 8.5 and 8.6: Community Ecology and Biodiversity

1. Species Interactions
   1. Mutualism
   2. Parasitism
   3. Commensalism, amensalism
   4. Competition (leading to niche partitioning and character displacement)
   5. Predator/Prey interactions (leading to evolutionary arms races)
2. Trophic Cascades and keystone species
3. Biodiversity

Teaching about Population Ecology, Community Ecology, and Biodiversity on  Learn-Biology.com

Here’s how I cover the objectives listed above (and more). Depending on where you are in the in the curriculum, “more” might or might not be equivalent to “better,” so read below.

Population Ecology 1: Key Attributes of Populations

This tutorial describes some of the dimensions by which population biologists describe populations. These include size, density, range, and dispersion patterns. I follow this by looking at age structure and survivorship curves. While this is important biology, it’s hard to know if this is what the College Board means in their objective about “How individuals in a population interact with each other and with their environment.” If you’re pressed for time, you can skip this tutorial.

Population Ecology 2: Understanding Population Growth

This tutorial teaches exponential growth and logistic growth. This includes limiting factors, carrying capacity, predator/prey-related population oscillations,  and r v. K selection.

The tutorial ends with a discussion of what I think is one of the most important issues facing our species: human population growth. Because that topic is definitely not on the AP exam, you can skip it if you’re pressed for time (but I hope you don’t).

Community Ecology 1: Species Interactions

This first community ecology tutorial starts with a discussion about niche and habitat. It then runs your students through the gamut of species interactions (mutualism, parasitism, commensalism, amensalism, predation, herbivory, and parasitoidism).

Two of these interactions receive special attention. The section on competition is expanded to include competitive exclusion, niche partitioning, character displacement, and realized v. fundamental niches. A section on evolutionary arms races gets students to take a closer look at the consequences of predator/prey and parasite/host interactions.

Community Ecology 2: Keystone Species and Trophic Cascades

This second community ecology tutorial looks at keystone species and trophic cascades. I built this tutorial around the HHMI video “Some Species are More Equal than Others.”

Community Ecology 3: Ecological Succession

The term “ecological succession” doesn’t appear in the College Board’s Course and Exam Description. I can’t imagine teaching a unit on ecology without teaching this concept. But if you have to skip a tutorial because you’re running out of time, then this would be the one to skip.

Community Ecology 4: Biodiversity

This tutorial looks at the three dimensions of biodiversity (genetic, species, and ecological). As a preview of the last topic of the course (ecosystem disruption) I provide an overview of biodiversity’s importance. The tutorial ends by looking at how biodiversity can be measured, and walks students through how to understand and use the Simpson Biodiversity Index.

Additional Resources

Flinn’s High School level POGIL on Population gives great reinforcement of exponential and logistic growth.

Ecosystem Disruption

Links

• AP Bio Exam Review Strategies (for teachers)
• AP Bio Teacher’s Guide Main Menu