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2005_campbl25

2005_campbl25 - 1 Chapter 25 Phylogeny and Systematics...

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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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2005_campbl25 - 1 Chapter 25 Phylogeny and Systematics...

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