Evolution

• Homologous features


  Physical features shared between species because of a common ancestor, like particular skeletal structures
• Vestigial structures


  Reduced or non functional versions of features that serve little to no function to an organism
• Analogous features


  Physical features that evolved separately in different organisms in response to the same environmental pressures, like how most species have eyes
• Convergent evolution


  When two separate species evolve to have common traits independantly
• Homologous genes


  Related genes found in different species used to determine if and when those species were evolutionarily related to each other
• Fossils


  Preserved remains of previously living organisms or their traces, dating from the distant past
• Strata


  Layers of rock that build up which provide a sort of timeline for roughly dating fossils
• Phylogenetic tree


  Diagram that represents evolutionary relationships among organisms (hypotheses not definite facts)
• Taxa


  blanket term for groups used for categorizing organisms like domain, family, species, subspecies, group
• Branch


  Line on a phylogenic tree
• Branch point (internal node)


  Where two branches diverge on a phylogenic tree
• Divergence event


  When one population species gets far enough away from the rest of it that it becomes its own distinct species, branch point on a phylogenic tree
• Most recent common ancestor


  At every branch point, the last animal that both species at the end of two different branches both descend from
• Root


  First line on a phylogenic tree, where all the species on it share their last most recent common ancestor
• Relatedness


  Measure of how recent two species' last common ancestor was
• Polytomy


  A branch point that has three or more different species coming off of it, showing that we don't have enough information to determine a more specific branching order