BISC 121Lg Chapter 22: BISC 121 Chapter 22 Notes
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Phylogeny- evolutionary history for a species or group of species. Systematics- focuses on classifying organisms and determining evolutionary relationships. Domain kingdom phylum class orders family genus species. Branch points- represent divergence of two lineages from a common ancestor. Sister taxa- groups of organisms that share an immediate common ancestor. 1st branch point represents a common ancestor of all taxa in the tree. Basal taxon- a lineage that diverges early and is near the group"s common ancestor. Polytomy- branch points where >2 descendent groups emerge. Homologies- phenotypic and genotypic similarities because of shared ancestry: similar morphologies often indicate close relationships. Analogy- similarities due to convergent evolution not ancestry: caused by similar environmental pressures and natural selection. Cladistics- common ancestry is primarily used to classify. Monophyletic- an ancestral species and all its descendants. Paraphyletic- an ancestral species and some of its descendants. Polyphyletic- a group of organisms with no common ancestor. Shared ancestral character- characteristic that originated in an ancestor.
