Overview

McGraw Hill Chapter 25Taxonomy and SystematicsKey Concepts:•Taxonomy•Phylogenetic Trees•Cladistics•Molecular Clocks•Horizontal Gene Transfer•TaxonomyScience of describing, naming, and classifying living and extinct organisms and viruses•SystematicsStudy of biological diversity and the evolutionary relationships among organisms, both extinct and modern•Taxonomic groups are based on hypotheses regarding evolutionary relationships derived from systematics•Hierarchical system involving successive levels•Each group at any level is called a taxon•Highest level is DomainAll of life belongs to one of 3 domainsBacteria, Archaea, and Eukarya•Previously kingdom was the highest (Linnaeus)Taxonomic hierarchySupergroup between a domain and a kingdom•7 eukaryotic supergroupsBelow domain and supergroup is KingdomPhylaClassOrderFamilyGenusSpeciesBinomial nomenclature•Every species has genus name and species epithet•Example: Homo sapiens•Genus name always Capitalized•Species epithet never capitalized•Both names are italicized•Rules for naming established and regulated by international associationsPhylogeny•Phylogeny - evolutionary history of a species or group of species•To propose a phylogeny, biologists use the tools of systematics•Trees are usually based on morphological or genetic data•Diagram that describes phylogeny•A hypothesis of evolutionary relationships among various species•Based on available information•New species can be formed byAnagenesis - single species evolves into a different speciesCladogenesis - a species diverges into two or more speciesBranch point in a phylogenetic tree are called nodes•Times when cladogenesis has occurred•Group species according to common ancestryClade consists of a common ancestral species and all of its descendant species

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