1. Note:
The last part of chapter 1 (on clutch size) will be considered after discussion of chapter 2 in a topic “Life history trade-offs”

2. Focal animal sample Time(min) Behavior 0:00 sit 3:33 walk 4:56 fight
6:35 rest
8:50 walk
10:00

3. Scan sample Interval Individual 1 2 3 4 5
samples must
be independent!
Interval Individual
0:00 walk walk fight fight walk
0:30 walk walk walk walk ov
1:00 walk rest feed walk feed
etc... 4

4. Focal behavior sampling
Tally instances of aggressive acts over set time

5. Why do animals play?
Practice for learning adult skills
Play stimulates pleasure centers
Play side effect of high metabolism in endotherms
Play enhances brain development
List independent, dependent variables and how you investigate:
Existing variation in pop’ns
Experimentally produced variation
Comparison of species

6. When testing hypotheses
Just because a hypothesized function appears to explain the behavior doesn’t mean that it is right.
Always consider alternative hypotheses and of course you need to test hypotheses.
Understand causal (proximate )vs. functional (ultimate) explanations
Also – remember we are seeing currently the result of past selection.

7. Consider the hyena pseudopenis….

8. Consider the hyena pseudopenis….
Why a pseudopenis?
Dominant females have high T and are aggressive…they get the pp. from high T
Pp serves to signal to females and reduces tensions among aggressive females during ‘greeting ceremony’
Sperm choice by females
Moral: The function of a behavior/structure presently may not explain why it first arose in the past..

9. Over-adaptionism
We sometimes tend to look for function and adaptation everywhere, but it can’t always be assumed
Consider the example of driving in US vs. Britain.
drive on right drive on left

10. Constraints on adaptation
Animals are often limited in what can possibly evolve….another reason to avoid assuming adaptation
Example: parental behavior in
mammals vs. birds
mammals nursing
Bird eggs

11. Comparative approach Social behavior in weaver birds
Solitary, group territory, or colonial

12. Comparative approach
Crook (1964) Tried to find correlations between ecology and nesting behavior
Aspects of diet
Food distribution
Predation pressure
Habitat

13. Weaver bird comparison

14. Comparative approach
Food type and predation pressure explained nesting behavior, mating system, sexual dimorphism
Jarman (1974) similar approach with ungulates
But there are issues with these early comparisons…

15. Home range size and diet in primates
Fruit/insectivores
Leaf-eating

16. Testis size vs. mating system
100
Multi-male 10
Testes
weight
Monogamous, or single male 1 1 10
100
Body weight

17. Comparing multi-species
Using a statistical approach w/quantifiable variables is more powerful and objective
Confounding variables
Continuous scale
Independence of data points

18. Testes weight Body weight Pan t. Pan pan. 100 Gorilla 10 Pongo
Tamarins, marmosets 1 1 10
100
Body weight

19. Testes weight Body weight Pan 100
Choosing genus instead of species level avoids
statistical bias towards groups with many species
Gorilla 10
Pongo
Testes
weight
Saguinus
Callitrix 1 1 10
100
Body weight

20. Independence by using ‘contrasts’
Instead of using pure species data for analysis, use amount of difference (contrasts) between species.