Biology 1001A Lecture Notes - Lecture 19: Speciation
18 Oct 2012
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Document Summary
Abiotic vs. biotic components: biotic: a way in which an organism interacts with other living things same members, or other species (species that eat it, or the species they eat, abiotic: everything else. Ecological interactions affect evolutionary processes: rates of speciation and extinction, patterns of selection and evolution. Biodiversity (number of species) reflects a balance between speciation and extinction. Biodiversity: a total number of species around (i. e. population, habitat, etc ) Most species extinct, that have ever lived. Ancestral species quickly differentiates into many descendant species. This causes: evolutionary innovations (i. e. types or species of flowers, release from competition (colonizing new islands can feed on new resources) and (mass extinctions) Background extinction level: mostly low, but nonzero, extinction risk independent of species age, some groups are more extinction prone . The big 5: 5 major extinctions decrease in number of species, most recent wiped out dinosaurs. Human impacts: hunting, species introductions, habitat and climate alteration.
