ENVI 101 Lecture Notes - Lecture 9: Holocene Extinction, Speciation, Lithosphere
18 Sep 2016
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Evolution: the process whereby the earth"s life changes over time through changes in the genes/alleles of populations of organisms in succeeding generations. Mutation (exposure to uv rays, chemical radiation, product of imperfect dna replication, etc. ) Drift (chance event that disproportionately changes the underlying concentration of a certain species) Natural selection (organisms" interactions with environment affects change) Theory of evolution by alfred wallace (1823-1913) and charles darwin (1809-1882) Organisms are constantly in competition with others. Some are better at survival and reproduction than others. The good traits would be passed on from generation to generation making them better suited for the environment. Darwin embarked on five-year voyage to map the world and ended on the galapagos islands. Darwin"s finches show similar but different characteristics. Study in the 1970"s shows that a drought caused a shift in species characteristics. The drought changed the morphology of certain seeds, leaving only large seeds favoring organisms with large beaks.
