Chap3 - heritable phenotypes in a population • In text...

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Natural Selection mechanism of evolutionary change Malthus intersection of population and food curves=point of crisis. Darwin read his essay and took away idea of struggle for existence 4 postulates (fig 3.4) individuals in populations are variable morphologically and in genes variations are (at least in part) passed to offspring=heritable pedigrees reconstruct how heritable it is some individuals are more successful in surviving and reproducing---Malthus selection increases as environmental context becomes more limiting not random, tied to variations. Some phenotypes survive and reproduce more successfully than others. Change in frequency---most offspring, more common phenotype. Natural selection =non-random differences in the avg reproduction and/or survival of different
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Unformatted text preview: heritable phenotypes in a population. • In text, modern example of Daphne finches—medium ground finch ◦ variable ◦ heritable-proportion of genetic control over trait in terms of inheritance ▪ measure heritability by comparing parents (midparent=avg of mom and dad) and kids ◦ vary in fitness =contribution of genes to future generations. ▪ Survival, reproduction, quality of offspring. ▪ '77 drought-less seeds, smaller and softer. Population of finches crashed. Fitness NOT random! Avg beak depth increased. ...EVOLUTION! • Can't always see natural selection at work ◦ Ex: longer horned lizards more likely to survive. ..natural selection?...
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