chap16 - Reconstructing and Using Phylogenies Chapter 16...

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Reconstructing and Using Phylogenies Chapter 16
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All of Life Is Connected through Its Evolutionary History All of life is related through a common ancestor: Phylogeny —the evolutionary history of these relationships Phylogenetic tree —a diagrammatic reconstruction of that history
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A lineage is a series of ancestor and descendant populations, shown as a line drawn on a time axis:
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When a single lineage divides into two, it is depicted as a split or node :
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Each descendant population gives rise to a new lineage, which continues to evolve:
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A phylogenetic tree may portray the evolutionary history of: All life forms Major evolutionary groups Small groups of closely related species Individuals Populations Genes
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The common ancestor of all the organisms in the tree forms the root of the tree.
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The splits represent events where one lineage diverged into two, such as: A speciation event (for a tree of species) A gene duplication event (for a tree of genes) A transmission event (for a tree of viral lineages transmitted through a host population)
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Vertical distances between branches don’t have any meaning, and the vertical order of lineages is arbitrary.
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Taxon —any group of species that we designate with a name Clade —taxon that consists of all the evolutionary descendants of a common ancestor Identify a clade by picking any point on the tree and tracing all the descendant lineages.
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Clades Represent All the Descendants of a Common Ancestor
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Evolutionary relationships among species form the basis for biological classification. As new species are discovered, phylogenetic analyses are reviewed and revised. The tree of life’s evolutionary framework allows us to make predictions about the behavior, ecology, physiology, genetics, and morphology of species.
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Homologous features: Shared by two or more species Inherited from a common ancestor They can be any heritable traits, including DNA sequences, protein structures, anatomical structures, and behavior patterns.
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Each character of an organism evolves from one condition (the ancestral trait ) to another condition (the derived trait). Shared derived traits provide evidence of
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This note was uploaded on 01/09/2012 for the course BIO 160 taught by Professor Howardhaemmerle during the Winter '12 term at Bellevue College.

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chap16 - Reconstructing and Using Phylogenies Chapter 16...

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