BIO 200 Lecture Notes - Lecture 4: Tiktaalik, Equidae, Hyracotherium
3 Apr 2017
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Darwin"s theory in three parts: there must be variation in the population, variation must lead to differences among individuals in lifetime reproductive success, variation must be transmitted to the next generation. 1: populations tend to overbreed relative to available resources, leading to a struggle for survival, better variations have better survival, survivors will reproduce and non survivors wont, traits leading to better survival and reproduction must be heritable. Grant and grant- variation in head and beak size in medium ground finches-seed availability. 1977-severe la ni a- extreme drought and population declined, withered vegetation, large hard seeds remained, small seeds quickly eaten. Surviving finches have bigger and deeper beaks than non survivors. 19842/1985- el ni o- unusually wet, abundant vegetation, abundance of small soft seeds and fewer large hard seeds. Larger beak sized bird population declined, smaller beaks flourished. Offspring will not acquire traits gained during lifetime.
