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Present Knowledge 1. Fossil Record shows history of life back 3.5 Billion Years with change over time. 2. Age of Earth 4.5 billion years old. 3. Heredity and Genetics (40 years after publication) 4. Comparative anatomy 1. Homologous – SAME evolutionary origin/structure DIFFERENT use/function 2. Analogous - SAME use/function DIFFERENT evolutionary origin/ structure Relatively Recent Knowledge 1. Molecular Biology - Degree of similarity in DNA yields relationships. Degree of difference + fossil knowledge = estimate of rate of evolution. 2. Ontogeny - Development of organism by the embryo yields information about evolutionary history of a species (phylogeny) Forces of evolutionary change • Natural selection – traits that improve survival or reproduction will accumulate in the population • adaptive change • Genetic drift – frequency of traits can change in a population due to chance events • random change Natural Selection • Selection acts on any trait that affects survival or reproduction – predation selection – physiological selection – sexual selection Predation Selection • Predation selection – act on both predator & prey • • • • behaviors camouflage & mimicry speed defenses (physical & chemical) Physiological Selection • Acting on body functions – – – – disease resistance physiology efficiency (using oxygen, food, water) biochemical versatility HOT STUFF! Some fish had the protection from injury variation of producing anti-freeze protein 5.5 mya The Antarctic Ocean freezes over Sexual Selection • Acting on reproductive success – attractiveness to potential mate – fertility of gametes – successful rearing of offspring Survival doesn’t matter if you don’t reproduce! Sexual selection QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. It’s FEMALE CHOICE, baby!