BIO 200 Lecture Notes - Lecture 8: Emperor Penguin, Parental Investment, Frequency-Dependent Selection
17 Mar 2017
School
Department
Course
Professor
Document Summary
Yes: bottleneck-natural event causes natural population to decline, finches were affected, did genetic drift change their beak size, the force that changed the finch beaks was natural selection, the only adaptive evolutionary force. Factors required for natural selection to operate: there must be variation, variation must lead to differences among individuals in lifetime reproductive success, variation must be transmitted to the next generation, selection is the only adaptive evolutionary force. *finesses switch: sexual selection-traits chosen to become better mates. 2: mate guarding, long term mating behavior, parental care, offspring spacing. Darwin notes: females often do not mate with the first male they seem, females are choosy. Energy- human eggs are 195,000 times larger than sperm and contain far more nutrients. Time- gestation limits new mating opportunities, maternal care takes time. Purely mathematical- females cannot have as many offspring as males. Take home message: for males, sex is cheap, for females, the after effects can be very costly.
