BIOL 1001 Study Guide - Final Guide: Late Devonian Extinction, Extinction Event, Adaptive Radiation
Document Summary
G2: discuss events that shaped the history of life, applying knowledge of microevolution, phylogenetics, and speciation: differentiate between background and mass extinctions, particularly in terms of adaptation. Mass extinction- the extinction of large number of diverse evolutionary groups during relatively short period of geologic time (about 1 million years). May occur due to sudden and extraordinary environmental changes. A mass extinction occurs when at least 60% of species present are wiped out within one million years. They are catastrophic episodes that wipe out huge numbers of species and lineages in short time, giving the tree of life a drastic pruning. They are polar opposite to adaptive radiation. Background extinction- the average rate of low level extinction that has occurred continuously throughout evolutionary history. Background extinctions are thought to occur when normal environmental change, emerging diseases, or competition with other species reduce certain populations to zero. Mass extinctions result from sudden, and temporary changes in environment.
