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Unformatted text preview: Chapter 26 Concept 26.1: Binomial Nomenclature- Carolus Linnaeus The two part format of the scientific name of an organism The binomial name consists of- Genus and species- These are always written in a different font (e.g., italics)- Genus is always capitalized; species is always lowercase- E.g., Homo sapiens Hierarchical Classification Linnaeus also introduced the system for grouping species in increasingly broad categories D o K eep P ipes C lean OF G aS (Domain Kingdom Phylum Class Order Family Genus Species) Classification Kingdom: Animalia; Phylum: Chordata; Class: Mammalia; Order: Primates; Family: Hominidae; Genus: Homo ; Species- H. sapiens Linking Classification and Phylogeny Systematists depict evolutionary relationships in branching phylogenetic trees Each branch point (node) represents the divergence of the two species Deeper branch points represent greater amounts of divergence Lines represent lineages Concept 26.2: Phylogenies are inferred from morphological and molecular data Morphological and Molecular Homologies Phylogenetic history can be inferred from similarities in homologous structures and genes when compared among organisms Generally- Similar morphology and similar DNA sequences=closely related species But, beware of analogous structures or molecular sequences (a.k.a., homoplasies)- Similarity may be due to convergent evolution (analogy), not shared ancestry (homology) Convergent: acquisition of the same biological trait in unrelated lineages Concept 26.3: Shared characters are used to construct phylogenetic trees Cladistics A clade is defined as a group which includes an ancestral species and all of its descendants. (i.e. monophletic) Cladogram: o a diagram depicting patterns of shared characteristics among species Clade within a cladogram: o a group of species that includes an ancestral species and all of its descendents 1 Monophletic Grouping Made up of an ancestral species and all of its descendents (one node and everything beyond it) Only monophyletic groups qualify as legitimate taxa in cladistics Paraphyletic grouping Consists of an ancestor and some, but not all, of that ancestors descendents (like dinosaurs exclude birds despite common ancestor) Polyphyletic grouping Grouping that lacks the common ancestor of the species in the group (things that fly- bats and birds; analogous features but no relation) Shared Ancestral and Shared Derived Characteristics Shared ancestral characteristic: homologous structure that predates the branching of a particular clade from other members of that clade Shared derived characteristic: evolutionary novelty unique to a particular clade The less nodes that separate them, the more closely related they are Concept 26.4: An organisms evolutionary history is documented in its genome Gene Duplications and Gene Families Gene duplication: the production of multiple copies of a gene within a genome...
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This note was uploaded on 03/06/2012 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.
- Spring '08