3 Two Ways of Building A Phylogenetic Tree

3 Two Ways of Building A Phylogenetic Tree - Two Ways of...

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Two Ways of Building A Phylogenetic Tree (3) Taxonomy, Phylogeny, and Problem of Convergence Convergence - organisms show similar traits not only because of common descent but because of parallel selection- ex: spindle shaped bodies and fins of fishes and dolphins Evolution may occur unusually fast, appear less related as result of: Environmental changes Colonization of previously uninhabited areas Loss of predators Phylogenetic Trees Based on Molecular Data Evolution as combined result of random DNA changes and drift including bottleneck and founder effects Changes in DNA random- replication errors, exposure to chem mut, cosmic radiation Interbreeding pop- mutant alleles spread in gene pool Pop splits into repro isolated subpop, each will accumulate own mutant alleles Introns- junk DNA, no known function- represents pure “genetic drift” Concept of Molecular Clocks Molecular clock, if mut accumulate at steady rate, indicates how long 2 species evolved independently Problems: Accumulation distorted by rapid changes in pop size: bottleneck and founder
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3 Two Ways of Building A Phylogenetic Tree - Two Ways of...

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