Natural selection the non random survival of random

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Natural selection = the non-random survival of random variants -- Natural Selection is not progressive, and does not lead to perfection. It can only filter variation in a population 342
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Natural Selection More nuances An appropriate metaphor, developed by the great French geneticist Francois Jacob, is to think of evolution as a “ tinkerer ” rather than an engineer Tinkering proceeds step-by-step. Including such complex structures as the eye This imposes important limitations, or “ evolutionary constraints ,” on evolutionary change Evolution cannot select on variation that does not exist, and biases in the production of variation can influence the route taken by a population 343 Convergent evolution of a camera-like eye 344 How does a camera-like eye evolve? 345
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Natural Selection More nuances - An adaptation must evolve by increasing the reproductive output of its possessor - Reproduction, not survival, determines which genes make it to the next generation - A gene that benefits reproduction at a young age, yet leads to wrinkles, grey hair, stiff joints, beer guts, and an enlarged prostate gland in old age, can be favored by natural selection - Natural selection never favors a trait “for the good of the species,” as it can only act on individuals and proceeds without foresight (no teleology!) 346 Natural Selection African wild dogs killing an Impala 347 The End
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