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Lecture 1 Classification review and Virology I.Classification + Evolution A.Classification1.Systematics- Diversity of organisms + evolutionary relationships-Taxonomy-Phylogenetics2. Taxonomy-a.Binomial nomenclatureEach species is assigned a unique 2 part name- Genus + Specific epithet b. Classification-Species-Arrange organisms in increasingly inclusive categories-Hierarchy Taxon- Grouping at any levelEach taxonomic level is more inclusive than the nextB. Evolution1.Accumulation of genetic change in a population over time- change in allele freq in populations2.Natural selection- mechanism- Acts on variationC. Basics of Phylogeny- evolutionary history1.Phylogenetic Tree- shows patterns of descent- hypothesis2.Componentsa. Branch point = node- divergence of two evolutionary lineages from a common ancestor(CA)b. sister taxa share an immediate CA- closest relativesc. Basal taxon- lineage that diverged early in history of a group- on a branch that originates near CAd. Polytomy- branch point from which more than 2 groups emerge e. Extant Species- at tips of branches Figure 26.4+ 26.5