Phylogenetic/Molecular Evolution (W4-L1)

Primitive or ancestral character state

Ancestral homology, homologous trait retained from the ancestor of the group

Derived character state

Closest relative on the phylogenetic tree

refers to everyone in the clade or node

refers to specific species in the same clade, but not all species in the clade

species completely separate from one another, often do not have a common ancestor, in different clades

Character: general category for which species manifest different Character states ex. Character: wing color, Character state: blue wings

Unique derived character state: A derived trait unique to one species in the group of study.

Shared, derived character state

• out-group: ancestral, closely related but not within the same group • Embryology: characters expressed early in development are ancestral relative to ones expressed late in development • Fossil evidence: characters found early in fossil record are ancestral

The use of different organisms to study the evolution of DNA an protein sequences (i.e. how and when did genes originate)

rate per generation at which an error in replication occurs

the rate per year at which a mutation fixes in a population ex. rate at which a mutation reaches 100%

Under neutrality, the probability of a new mutation spreading in a population and fixing is 1/2N where 2N(mew) = Number of new mutation entering a population (mew) = mutation rate conclude fitness effects are a result of mutation and genetic drift only

• Not all DNA translates into protein • Not all protein variation translates into phenotypic variation • Not all phenotypic variation translates into fitness differences

• sequence evolution in mammals is rapid: 1 amino acid per 1.8 year • such a high mutation frequency suggests the majority of substitution have no fitness effects • conclude fitness effects are a result of mutation and genetic drift only