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Biogeographic Realms and the Geography of Diversification March 11 th, 2014
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Cosmopolitan
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Endemic
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Relict
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Disjunctions
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Faunal regions Floral regions Floral & faunal biogeographic regions
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Evolution of Mammals Mammals first appeared 220 mya Small in size; egg layers Small size and warm-blooded physiology allowed some mammals to survive KT Extinction Adaptive radiation occurred as mammals evolved to fill the many vacant niches caused by the extinction of the dinosaurs
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Marsupials and Placentals
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Wombat Tasmanian devil Extinct marsupial lion opossum Marsupials
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Monotremes Egg-laying mammals Have cloaca – serves as anus, urinary tract, and reproductive tract Animalia, chordata, mammalia, monotremata Platypus Spiny anteater
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Wallace’s Line Biogeographic line – a line dividing biogeographic realms
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North American Deserts
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Islands Continental Islands – support plants and animals that are closely related to forms on the nearby mainland –Madagascar, New Zealand, British Isles Oceanic Islands – typically have biotas of lower taxonomic richness – often forms are endemics that are well differentiated from their apparent relatives on nearby continents –Hawaii, Galapagos
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Convergence Convergent evolution – when distantly related organisms have independently evolved similar adaptations because they live in similar physical environments Euphorbia Cactaceae S.A. Cactaceae N.A.
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Convergence
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