Testing Hypotheses in Animal Behavior (4)

Includes testing hypothesis (hypo + question), 3 Types of study (Observation, experimental, and comparative), an older comparative study (good and bad), and a new comparative study (independent/primates)

Define these terms:

Hypothesis

Prediction

Type 1 error

Type 2 error

1. Statement that answers the “why”

2. Follows a hypothesis (predicts because of “why”)

3. An alternative hypothesis confirms prediction

4. Prediction does not confirm correct hypothesis

How does a statistical hypothesis differ from a scientific hypothesis?

Statistical: no significant pattern (null hypothesis)

Science: significant pattern (functionally important differences)

What are the three approaches to study and a brief description of each?

1. Observational - compare within species

2. Experimental - manipulate a variable

3. Comparison - look at genotype similarities

Explain an observational study further. What does it compare? What are the limitations?

1. Compares solitary versus groups

2. Alternative hypothesis could affect the outcome

Explain an experimental study further. What is it? What are limitations?

1. Vary one factory at a time

2. Unnatural treatments could skew data or covariance with a manipulated variable are not controlled for.

Who did the older comparative study with primates? What 3 things was different about the study that allowed for comparisons?

1. Brock and Harvey

2. They used genera instead of species comparisons to reduce similarities due to genes, a continuous scale of measurement, and multivariate/alternative hypotheses.

What were the three patterns observed in Brock + Harvey’s primate study, problems/alt. hypos with each, and their results?

1. Food types and home range size

   1. Problem = body size (larger animals need more space) so they graphed home range by weight and grouped data by food.

   2. Found that insectivores had higher range than folivores.

2. Sexual dimorphism in body mass

   1. Problem = was dimorphism really for niche separation and not sexual selection? If so then monogamous couple would have more separation and if not then polygamous groups would have more separation (females like larger males = more mating).

   2. Niche separation was not supported, and more separation was found in polygamous groups.

3. Testes size and breeding system

   1. Found that increased size meant females were mating with more than one male (sperm competition)