Comparative Method

Question 1

What are three things which must be done in comparative studies?

Answer 1

• Correlate behaviours to ecology across species (or other taxa)
• Reconstruct evolutionary history
• Separate effects of ecology (selection) from phylogeny

A good sample with a known phylogeny is preferred for comparative studies.

Question 2

What are two criteria for choosing variables in a comparative study?

Answer 2

• Relevant

- Measurable

Question 3

What are three steps to doing a comparative study?

Answer 3

1. Choose relevant, measurable variables
2. Control confounding variables (eg. using statistical methods or control measures)
3. Consider phylogeny

Question 4

What are three ways of ensuring data points are independent in comparative studies?

Answer 4

• Compare independent taxa where variation is highest (eg. group similar taxa together)
• Make a phylogenetic tree and count transitions
• Contrast phylogenetically independent traits (eg. variation among different groups, grouped within phylogenetic tree so that the data is re-expressed as differences within branches)