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35 Cards in this Set
- Front
- Back
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shared ancestry |
all living organisms are related to one another |
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phylogenies |
estimates of genealogical (evoluionary) relationships; exclude fossil species and only include a fraction of extant species; history of speciation events |
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speciation |
the process of species formation |
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topology |
specifies a nested set of common-ancestry relationships |
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sister species |
two species that are each others closest relatives |
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internal nodes |
indicate speciation events and MRCA |
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root node |
most inclusive node, it is the MRCA of the entire tree |
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terminal nodes |
species or groups of species; extant |
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internal branches |
connect two speciation events |
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terminal branches |
subtend the tips of the tree |
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cladogram |
branch lengths are arbitrary, only topological information |
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phylogram |
branch lengths reflect the amount of character change |
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chronogram |
branch lengths reflect temporal information |
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monophyletic groups (clades) |
natural groupings, it includes all of the descendant species of a given common ancestor |
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paraphyletic |
unnatural groups; includes some but not all of the descendants of a given common ancestor |
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polyphyletic groups |
exclude the MCRA of the included species |
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polytomies |
estimated phylogeny; shown for uncertainty |
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homologous |
any features shared by two or more species that have been inherited from a common ancestor |
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ancestral trait |
a trait that was present in the ancestor of a group |
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derived trait |
a trait found in a descendant that differs from its ancestral form |
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synapomorphies |
a shared, derived trait |
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convergent evolution |
independently evolved traits subjected to similar selection pressures may become superficially similar |
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traits |
observable features of an organism; heritable, discrete, fixed within species, potentially variable between species |
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homology |
similarity in a trait among different organisms that is due to inheritance from a common ancestor |
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homoplasy |
similarity in a trait among different organism that has evolved independently |
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data matrix |
table of trait information |
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invariant distribution |
all species have the same state |
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uniquely distributed states |
one species has one state, all other species have the other state |
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shared-derived states |
two or more species share the same state |
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syn |
shared |
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apo |
derived |
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morph |
form |
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occam's razor |
prefer the competing hypothesis that minimizes the number of ad hoc assumption (prinicple of parsimony) |
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ingroup |
the set of species that you want to estimate evolutionary relationships |
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outgroups |
used to objectively chose the correct rooting |
