OEB 53 Chapter : Origin Study Guide 7&8

• School: Harvard University
• Department: Organismic and Evolutionary Biology
• Course: OEB 53
• Professor: Andrew Berry

Document Summary

The origin of the species: chapter 4 (natural selection) Darwin argues that natural selection requires heritable variation and a struggle for survival in order to take place. He states that changing environmental conditions allows the greatest potential for evolutionary change. Darwin also points out that population size is important because the more individuals there are, the greater the chances that favorable variations will arise. Darwin notes that sexual selection is less severe than natural selection: the losing male, although he survives, will produce few or no offspring. He also observes that victors are not necessarily more fit in terms of survival, but are better adapted to win at competing for females (versus natural selection, being better adapted for survival). Darwin makes the case that sexual selection is a relatively weak factor compared to natural selection, even as he posits that female selection could influence male traits over time.