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Unformatted text preview: 1 Chapter 25: Phylogeny and Systematics MacroevolutionaryRelatedness Phylogenies are evolutionary histories Systematics is an analytic approach to understanding the diversity of relationships of organisms p. 491, Campbel & Reece (2005) Taxonomy is the ordered division of organisms into categories based on similarities and differences. p. 495, Campbel & Reece (2005) Shown is a phylogenetic tree Microevolution is Any time you consider natural selection genetic drift mutation gene flow between populations the randomness of mating within populations you are considering microevolutionary processes Indeed, microevolution is all those evolutionary things up to and just about including the act of speciation itself Macroevolution is Any time you consider the likelihood of births of new species (speciation events) the likelihood of the death of species (extinction) the adaptive radiation of lineages (birth of many species) mass extinction (death of many species) evolutionary relationships between species the evolutionary history of a lineage biogeography, or shared derived characters you are considering macroevolutionary processes Connections... Adaptation of a species to its natural environment (microevolution) will not necessarily have a positive impact on the ability of that species to give rise to descendant species (macroevolution) That is, microevolution and macroevolution are not identical processes However, microevolutionary processes do impact on macroevolutionary processes For example, macroevolution is affected by the adaptations displayed by organisms (e.g., dispersal or dormancy ability) and adaptations are a product of selection (a microevolutionary process) Fossils 2 Classifying Organisms Fossils allow us to compare extinct organisms with modern organisms People study fossils to understand past environments plus to discover clues to evolutionary relationships among organisms Taxa (sing. taxon) are units of classification of organisms So far we have considered the taxonomic categories species & domain Ideally, all taxonomic categories group organisms according to evolutionary (blood) relationships Also ideally, more closely related species should be grouped into more-similar taxonomic categories Taxonomic Categories Do ( Domain ) Keep ( Kingdom ) Privates ( Phylum ) Clean ( Class ) Or ( Order ) Forget ( Family ) Getting ( Genus ) Sex ( Species ) Other Mnemonics Darn Kids Picking Cacti On Fridays Get Stuck...
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