Learning to describe and quantify animal behavior

1. Learning to describe and quantify animal behavior

2. Objectives • 1) Be able to describe the scientific method for making observations and testing hypothesis about animal behavior • 2) Be able to compare and contrast the multiple met

3. It all begins with an observation… Squid Inking

4. Scientific Method • Observations • Form a hypothesis • Null hypothesis • Alternate hypothesis

5. Scientific Method • Make Specific Predictions • Determine your independent and dependent variables • (Independent variable) causes a change in (Dependent Variable) and it isn't possible that (Dependent Variable) could cause a change in (Independent Variable). • Determine what specific behavioral response are you measuring • Are you measuring the state of an animal or an action/event that is occurring?

6. Scientific Method • Test Predictions • Identify or develop sampling or experimental techniques to test hypothesis • Select analytical tools to determine if your data supports you null or alternate hypothesis

7. Behavior Experiments: Testing your hypothesis • The method you use often depends on your question • 1) What is the effect of factor X on variable Y? Manipulative Experiments - • Pros: allows you to isolate variables • Cons: experiments can be difficult and time consuming; behaviors hard to observe in some manipulations

8. Behavior Experiments: Testing your hypothesis • The method you use often depends on your question • 1) “Are there spatial or temporal differences in Variable Y?” • Requires survey data to sample behaviors or another variable at two different sites or times • Pros: sampling is often easier than manipulation • Cons: Correlation is not causation! • Many times survey data is just a first step

9. Behavior Experiments: Testing your hypothesis • For instance: • Do fish avoid shallow water to avoid foraging birds? • Hypothesis: fish numbers should be lower in shallow habitats with high numbers of foraging birds

10. Behavior Experiments: Testing your hypothesis • Other variables might explain this pattern • Seagrass density? • Nutrients? • Abundance of fish prey? • Human disturbance? Bird abundance Fish abundance in shallow habitats

11. Behavior Experiments: Testing your hypothesis • The method you use often depends on your question • But what if your question is about the difference in strategies or adaptations within or amongst species? • You can perform comparisons between individuals of the same species • Do fish in schools avoid predators better than solitary fish? • Often complicated by confounding variables- solitary animals behave differently than schooling animals

12. The comparative method • A comparison of groups of related species to determine how their differences in behavior reflect their differences in ecology

13. Testing your hypothesis • Method depends on your question • 1) Manipulative Experiments • 2)Comparisons between individuals of the same species • Often complicated by confounding variables • 3) Comparisons among species • Differentiate different adaptations, or environmental selection on entire species • Why does Species A use X Strategy and Species B use Y strategy?

14. Black Back vs. Kittiwake gulls • Black back gulls nest on the ground • Observed behaviors • Adults fly over approaching predators and send out alarm calls for attacks • Adults don’t defecate near nests • Remove empty egg shells (white interiors) • Chicks are camouflaged and hide in vegetation • Hypothesis: These are adaptations to avoid predation, because gulls nests are vulnerable to attack on the ground

15. Black Back vs. Kittiwake gulls • Kittiwake gulls nest on cliffs, and are therefore harder to attack and less vulnerable to predation pressure

17. Problems with the Comparative Method • Alternative hypothesis • Could the difference between these two gulls be due to other traits? Competition? Proximity to feeding grounds?

18. Problems with the Comparative Method • Alternative hypothesis • Doesn’t quantify ecological variables • Do eggshells make chicks more vulnerable to predators

19. Problems with the Comparative Method • Alternative hypothesis • Doesn’t quantify ecological variables • Alternative adaptive peaks or non-adaptive differences • Not all differences between species must be adaptive

20. Problems with the Comparative Method • Alternative hypothesis • Doesn’t quantify ecological variables • Alternative adaptive peaks or non-adaptive differences • No Statistical Analysis • Common in many early ecological studies

21. Phylogenetically Independent Contrasts • Species are not independent • Species can share traits because they share a common ancestor

22. Phylogenetically Independent Contrasts • But what if you found out Animals A,B,C all descended from a common ancestor? F A D B C E

23. Phylogenetically Independent Contrasts • Hyptohesize Larger rodents have larger range sizes (due to metabolic needs) • Compile species values, and then regress body mass against home range size Home range (Dependent) Body Mass (Independent)

24. Phylogenetically Independent Contrasts • However, a species body size or home range size is not independent of its relatives • Therefore species are not necessarily independent data poits

25. Phylogenetically Independent Contrasts • Species are not independent • Species can share traits because they share a common ancestor • Confounds independence • Must take evolutionary relationships/phylogeny into account and remove phylogenetic independence

26. Phylogenetically Independent Contrasts • Felsenstein (1985) • A set of traits • A fully resolved phylogeny • A model of evolution • (time of species evolution, time of divergence etc)

28. Comparative studies • Most useful to examine broad trends in evolution, social organization, and ecology • Proper use requires • Controlling for social organization • Avoiding or addressing confounding variables using experimental manipulation • Using phylogenetically independent contrast to account for evolutionary constraints • Account for alternative hypothesis and address them when necessary

29. Returning to comparing gull species • Comparative studies can yield specific hypothesis to test with experiments • What happens if egg shells aren't removed?

30. But behavior is not always adaptive • Some behaviors are just a different way to accomplish the same goal • Unfortunately, determining if a behavior isnt adaptive is an exclusionary case

31. Class Exercise Designing Behavioral Experiments Sea Turtles and Light Pollution