BIO120H1 Lecture Notes - Lecture 3: Adaptive Radiation, Endemism, Biogeography
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BIO120H1 Full Course Notes
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Document Summary
Earth is very old, allows for immense amount of time for biological evolution. Intermediate forms provide evidence for common ancestors linking features of living organisms. Fossils in younger strata increasingly resemble modern species in same region, while older strata show increasing differences. Animals stick up fur when cold or scared. Only evolution explains vestigial characters, design doesn"t. More olfactory genes have become inactivated in species that rely less on sense of smell. Humans have high % of dead olfactory genes (over 50%) Dead gene for vitamin c synthesis (glo gene) Inactivation of glo gene leads to inability to synthesize. Humans have lost ability, get vitamin c from diet. Through mutation & gene activation, became lost. If not necessary, natural selection can lead to a loss. Organismal features are consistent with modifications of pre-existing structure. Not expected if each organism was optimally designed. Approx 500 genes shared across all forms of life.
