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Evolution 1. Change in the inherited characteristics of biological populations over successive generations2. Mutation- change in genes, random3. Natural selection- traits that are successful get passed on, nonrandomAdaptation1. Specializations of a basic “organ” an organism possesses that performs 1 or more functionsa. Central concept of evolution theory is that the various adaptations evolved from a common origin2. Darwin’s contributiona. Proposed the concept of common ancestry for diverse organisms withobvious similar featuresi. Evolutionary divergence- increase the degree of difference through timeb. Large geographic distribution of lifei. Evidence1. Large flightless birds different in America, Europe, Africa, and Asia2. Isthmus of Panama3. Island species4. Galapagos tortoise, finchesc. Anatomical evidence in embryos in support of common ancestry for vertebratesd. Homologyi. Similar structures hinting at common ancestore. Vestigial organsi. Have a feature that no longer serves a purposef. Natural selection is the mechanism of evolutioni. If a mutation occurs and isn’t helpful, it will go awayii. Survival of the fittestiii. Traits that allow you to adapt to environmentiv. Artificial breeding- why not natural breeding (dog breeding)v. Requires1. Survival of particular genetic traits2. Production of offspring with particular genetic traitsSpeciation1. Darwin’s Challenge- How organism passes along favorable genetic trait to offspring2. Mendel’s experiments lead to modern geneticsa. Punnet squareb. How genetics are passed on3. Each parent contributes ½ of genetic material (1/2 of its chromosomes)4. Genes are chemical structures that undergo chemical changes called mutations5. Speciation- the origin of a new species from individuals of a preexisting species 6. Speciation eventa. Branching event on a tree of lifeb. Creates new reproductive barriers between preexisting species and new speciesc. Often occurs as a result of spatial isolation of one population- geographicEvolutionary Trends1. Fossilsa. Rates of origination, evolution, and extinctionb. Evolutionary radiations- point in time when degree of differences of an organism increases2. Graduala. Change in oyster bodies- become flatter over time3. Rapida. Mutationb. Genetic change in a regulatory gene4. Both patterns have been documented from the fossil record5. Fossilsa. Only direct evidence6. Extinctiona. Predationb. Diseasec. Competitiond. Change in physical conditions7. High rates of extinction make useful index fossils (time/ event markers)8. Mass extinctionsa. Often linked to a major environmental change b. Can serve as an event marker bedc. Earth history average extinction rate- 1 extinction a dayd. 20-30 projected predictions- several hundred species a day9. Evolution is irreversiblea. Has directionalityb. Dollo’s law- evolutionary transition resulting from at least several genetic changes is unlikely to be reversed by subsequent evolution i. Confirmed by analysis of fossil recordii. Once a species is extinct, it does not

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LSU GEOL 1003 - Lecture notes

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