general phylogeny Flashcards
derived character state
a shared character state that arose in the most recent common ancestor of a taxon, but not in an earlier one
ancestral character state
a character state inherited from a far ancestor (NOT the most recent common ancestor of a taxon)
plesiomorphic character state
ancestral character state
apomorphic character state
derived character state
homologous structures
arise from the same structure in a common ancestor
embryonic origin as evidence for homology
similar structures can have significantly different embryonic origins, which would be great proof that they’ve arisen from convergent evolution
if structures (even if they appear very different or have different functions) arise from the exact same embryonic origin, this is very good evidence for homology
when using as evidence, be as specific as possible!
specific function vs biological role
when considering the specific function of a structure, think EXACTLY
ex. generate electrical field, or sense sound waves NOT see or hear
phylogeny
the evolutionary history of any group of organisms
phylogenetic tree
graphical representation of a hypothesis a group of organism’s evolutionary relationship
cladogram
branch length doesn’t represent a specific amount of changes or lengths of time
just because two ancestors are in line on a cladogram, they weren’t necessarily alive at the same time.
extant
alive today
extinct
dead and gone
could you count nodes to det. which was more recent?
no because any branch could be expanded!
what evidence could you use to construct phylogenies
molecular (structure of proteins, genetic)
developmental
embryonic origins
morphological characters - synapomorphies
convergent evolution
produces similar characters due to similar evolutionary pressures, not because or inheritance from a common ancestor
