BIO 102 Lecture Notes - Lecture 3: Horizontal Gene Transfer, Molecular Phylogenetics, Polyphyly
26 Sep 2016
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Monophyletic group: (clade) includes ancestral species and all its descendants, share derived characters. Paraphyletic group: common ancestor and some, but not all, of its descendants, share ancestral characters. Polyphyletic group: several evolutionary lines that don"t care recent common ancestor, unnatural grouping that misrepresent evolutionary relationships. Science of molecular systematics focuses on molecular structure to clarify evolutionary relationships. All living things can be identified by unique sequences of dna or rna, like a genetic maker or barcode. Method: compare dna sequence of a highly conserved gene. The more subunit sequences of 2 species correspond, the more closely related the species are considered to be. Molecular systematics: ribosomal rna"s have been extensively used to determine evolutionary relationships among bacteria. When we think of how organisms acquire genes, vertical gene transfer: genes are transmitted from parent to offspring within the same species. Horizontal gene transfer: gene swapping between organisms in one taxon. Accumulation of genetic changes within a population over time.
