Biology 1201A Chapter Notes - Chapter 20: Phylocode, Parallel Evolution, Cladistics
18 Dec 2017
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Chapter 20 understanding the history of life on earth. Phylogenies: show the evolutionary history of a group of organisms. Phylogenetic trees: formal hypotheses identifying likely relationships among groups of organisms. Based mainly on morphological characters also includes behaviour patterns, physiology, cellular structures, subcellular structures, molecular sequences and organ systems. Seek characters that are independent markers of genetic similarity and differentiation. Tries to exclude differences caused by environmental factors. Homologous characters: characters in different organisms that are similar because they were inherited from a common ancestor that also had that character. Similar in structure but might not be in function. Emerge from comparable embryonic structures and grow in similar ways. Homoplasies: characteristics shared by a set of species but not present in their common ancestors; often the product of convergent evolution. Convergent evolution: the evolution of similar adaptations indistinctly related organisms that occupy similar environment. Analogous characters: characters in different organisms that serve the same function that evolve in independent lineages.
