Note Focal animal sample Timemin Behavior 000 sit 333 walk 456 fight 522 walk 635 rest 850 walk 1000 Scan sample Interval Individual 1 2 3 4 5 ID: 713621
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Slide1
The last part of chapter 1 (on clutch size) will be considered after discussion of chapter 2 in a topic “Life history trade-offs”
Note:Slide2
Focal animal sample
Time(min) Behavior
0:00
sit
3:33 walk4:56 fight5:22 walk6:35 rest8:50 walk10:00Slide3
Scan sample
Interval Individual
1 2 3 4 5
0:00 walk walk fight fight walk0:30 walk walk walk walk ov1:00 walk rest feed walk feedetc...
1 2 3 4 5
samples mustbe independent!
1 2 3
4 Slide4
Focal behavior sampling
Tally instances of aggressive acts over set timeSlide5
Why do animals play?
Practice for learning adult skills
Play stimulates pleasure centers
Play side effect of high metabolism in endotherms
Play enhances brain developmentExisting variation in pop’nsExperimentally produced variationComparison of species
List independent, dependent variables and how you investigate:Slide6
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.When testing hypothesesSlide7
Consider the hyena
pseudopenis
….Slide8
Why a
pseudopenis
? Dominant females have high T and are aggressive…they get the pp. from high TPp serves to signal to females and reduces tensions among aggressive females during ‘greeting ceremony’
Sperm choice by femalesMoral: The function of a behavior/structure
presently may not explain why it first arose in the past..Consider the hyena pseudopenis….Slide9
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.
Over-
adaptionism
drive on right drive on leftSlide10
Animals are often limited in what can possibly evolve….another reason to avoid assuming adaptation
Constraints on adaptation
Example
: parental behavior in
mammals vs. birdsBird eggs
mammals nursingSlide11
Comparative approach
Social behavior in weaver birds
Solitary, group territory, or colonialSlide12
Crook (1964) Tried to find correlations between ecology and nesting behavior
Aspects of diet
Food distribution Predation pressure Habitat
Comparative approachSlide13
Weaver bird comparisonSlide14
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…
Comparative approachSlide15
Home range size and diet in primates
Leaf-eating
Fruit/insectivoresSlide16
Testis size vs. mating system
Testes
weight
Body weight
110
100
1
10100
Monogamous, or single male
Multi-maleSlide17
Comparing multi-species
Using a statistical approach w/quantifiable variables is more powerful and objective
Confounding variables
Continuous scale
Independence of data pointsSlide18
Testes
weight
Body weight
1
10100
1
10100
Gorilla
Pongo
Tamarins, marmosets
Pan pan.
Pan t.Slide19
Testes
weight
Body weight
1
10
100
1
10
100
Gorilla
Pongo
Pan
Saguinus
Callitrix
Choosing genus instead of species level avoids
statistical bias towards groups with many speciesSlide20
Instead of using pure species data for analysis, use amount of difference (contrasts) between species.
Independence by using ‘contrasts’