CAS BI 107 Lecture Notes - Lecture 11: Adaptive Radiation, Volcanism, Axial Tilt
1 Oct 2015
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Mass extinction typically results from external forcing factors. Characterized by the cambrian explosion -- formation of multicellular eukaryotes and every major phylum of animals. After every mass extinction since then, adaptive radiation occurred. The mass extinction eliminates the dominant groups, allowing for new species to flourish. Release from pathogens, predators and other limiting factors. Can be triggered by extinction, colonization events and morphological innovations. Critical component for adaptive radiation is ecological opportunity (ex. Galapagos finches being on the same habitat and learning to utilize all resources) The most important factor leading to adaptive radiation is : mass extinction, colonization of new regions or habitats, evolution of a novel morphology and/or behavior, ecological opportunity. Answer: d (mass extinction leads to adaptive radiation but isn"t the most important) Mass extinction is most often caused by : rapid environmental change, extraterrestrial bolide impact, plate tectonics, volcanism. Answer: a (the other three examples are examples of what can generate environmental change)
