Phylogeny 2

Question 1

can we treat each species as a replicate for evolutionary studies (2)

Answer 1

• no, species aren’t independent replicates because they evolved from common ancestors
• using species as replicates could lead to a proposed pattern that is just due to coincidence

Question 2

sister clade comparison (2)

Answer 2

• method where you find a pair of sister clades that differ in a trait and see which clade has more species
• if many pairs show the same pattern, where the one clade with a certain trait has more species than its sister with a certain trait, then this is evidence that the trait affects diversification

Question 3

what are the general rules for parsimony

Answer 3

• if all members of a clade have the same state, than all of the ancestral nodes up to and including the MRCA, have the same state
• if two sister clades have different states, then the state in their MRCA depends on the neighbouring clades

Question 4

what can correlations between two traits tell us (2)

Answer 4

• might suggest two traits are functionally related and can give us a hint about: evolutionary adaption or physiological, biochemical and cellular mechanisms
• correlation reflects function and adaptation, but can be misleading

Question 5

to tell correlation from coincidence, in what cases do we need more repetition (2)

Answer 5

• when assessing the correlation between two traits

- when assessing whether a certain trait allowed a clade of species to diversify

Question 6

pseudoreplication

Answer 6

• using replicates that are actually not independent; samples have some other sort of connection such as a common genetic history

Question 7

in phylogenetic correlation, what is the relevant sample size

Answer 7

• the number of evolutionary events, not the number of species

Question 8

comparative biology/comparative method

Answer 8

• approach of finding patterns across many species to understand biological processes