Lecture 3 Flashcards
(17 cards)
What are phylogenetic trees?
hypotheses about relationships between taxa
At what level can a phylogeny be done?
at any taxanomic level
What does homoplasy mean?
End up on the same character state but from different origin (starting points)
How many character states are possible when building a phylogeny with genetic data?
four possible character states
What are slowly evolving genes useful for?
distantly related species
in terms of constructing ohylogency, What are rapidly evolving genes useful for?
for closely related lineages
What is parsimony?
the simplest evolutionary explanation that fits the evidence
What is the outgroup?
the most distantly related to the other species of a phylogenetic tree. has the fewest number of changes
Are traits that all sepcies share useful for inferring phylogenies?
no
Are traits that only one species has useful for inferring phylogenies?
no
What are the most useful character traits for inferring phylogenies?
shared derived traits
Why is estimating phylogenies complicated due to homoplasy?
- homoplasy means independent origin of similar traits in different lineages
What are two possible causes of homoplasy?
- repeated evolution of a trait (convergent evolution)
- loss of a trait
Where is the outgroup on a phylogenetic tree?
at the root of the tree
What is homology?
traits that are shared because they are inherited from a common ancestor (must mean the trait is useful)
What are synapomorphies?
these are shared derived traits that evolved in the common ancestor of the group and were inherited by all of its desendents
Is character similarity more due to homology or homoplasy?
The consequence of this is that a similarity in a derived character state is more likely to be due to a common ancestry (homology) than through random or non-random assimilation of the same feature in two different lineages (homoplasy).
