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Evolution (Molecular Evidence (gene expression (which genes are turned…
Evolution
Molecular Evidence
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For example, we can learn about the evoulution of humans and our closest living relative, the chimpanzee, by comparing chromosomes
humans have 23 pairs of chromosomes, while chimpanzees have 24 pairs
Speciation
Species
a popuation of similar organisms that can interbreed to produce viable, fertile offspring
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Microevolution
small scale, single popuation
Macroevolution
large scale, across species
Mutation
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can be beneficial, neutral or harmful
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Natural Selection
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when the above 3 criteria are met, evolution by natural selection will occur
Sexual Selection
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sexual selection is often powerful enough to produce featuresthat are mmore harmful to the individual's survival
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Migration/Gene Flow
movement of individuals, and their genetic material, from one population to another
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If gene versians are carried to a population where these gene previously didn't exist, gene flow can be a very important source of genetic variation.
Genetic Drift
genetic drift affects genetic makeup of the population, but unlike natural selection, through an entirely random process
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In each generation, some individuals leave behind a few more desendants than other individuals -- by chance
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Adaptive Radiation
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These species are distinct from one another, but are closly related
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Arificial Selection
instead of nature, people select which organisms get to reproduce
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Ex: produce, pets, livestock
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Homologous vs Analogous
Homologous
characteristics in different organisms that are similar because they were in herited from a common anscestor that also had that characteristic
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Analogous
have seperate evolutionary orgins but are similar because they have both experienced natural selection that shaped them in a similar wy
Convergent evolution
process in which two distinct lineages evolves a similar characteristic independently of one another
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Charles Darwin
A visit to Galapagos Islands in 1835 helped Drwin formulate his ideas on natural selection. He found several species of finches adapted to different enviromental hiches. THe finches also differed in beak shape, food source and how food was captured