Biology 1001A Lecture Notes - Lecture 9: Background Extinction Rate, Evolutionary Arms Race, Adaptive Radiation
15 Mar 2015
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Document Summary
Ecology: interactions between organisms and their environment. Ecological processes affect evolutionary processes: rates of speciation & extinction, patters of selection and evolution. Biodiversity: total number of species in a geographic region (earth, genetic variation in each population, constantly turnover and replacement of species, reflects balance between speciation and extinction. Adaptive radiation: extreme speciation: ancestral species quickly differentiates into many different descendent species, triggering factors. Evolutionary innovation: allows lineage to open up to many ecological niches. Release from competition (ancestral species colonizing new islands) Part of the process of evolution ultimate fate of all species. Today there are more extinct than living species. Fossil record demonstrates a continuum in time from one species to another. Background extinction rate: average rate of extinction of taxa through time, mostly low, but nonzero always happening, extinction risk independent of species age, some groups more extinction prone . Environments change poorly adapted organisms do not survive and reproduce.
