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Chapter 26 Phylogeny -- Evolutionary history of a species or group of related species; attempts to trace macroevolution. Macroevolution – Origins of broader groups of organisms; studied in relation to major events of environmental change. Systematics -- Study of biological diversity in an evolutionary context. Current biological diversity reflects past episodes of speciation and macroevolution. Taxonomy – Component of systematics which includes identification and classification of species. System used today was developed by Carl Linnaeus in the 18th century. Two main features: 1) sort and name separate species, and 2) organize them into categories based on relationships. Binomial nomenclature: Two-part Latin name unique to each species. Ex: Genus Felis includes many species of related organisms (cats). Species Felis silvestris; Felis lynx; Felis leo. Kingdom Animalia Phylum Chordata (phyla, plural) Class Order Family Genus (genera, pl) Species Mammalia Carnivora Canidae Canis Canis familiaris 5 kingdom system Monera (bacteria) Protista (algae and protozoans) Fungi Plantae Animalia 6 kingdom system Archaebacteria Eubacteria Protista Fungi Plantae Animalia Outward similarities; embryonic development; life cycle stages. Homology – similarities due to common ancestry. But superficial features don’t always reflect evolutionary relationships. Analogy -- Similarities due to convergent evolution, not common ancestry. Convergent evolution -- Similar characteristics due to sharing similar ecological roles; natural selection shapes adaptations. Phenetics: makes no evolutionary assumptions. Comparison is made of as many phenotypes as possible. If enough characteristics are compared, homology will overshadow analogy.(?) Overall phenotypic similarity is not a reliable indicator of phylogeny.(?) This may be more useful for analyzing DNA sequence data. Cladistics: classifies organisms according to phylogeny. Cladogram -- a branching “family tree”. Each species in the cladogram has a mixture of primitive characters that existed in the common ancestor and characters that evolved more recently. A major difficulty in cladistics is finding appropriate categories for each branch point.