1. Explain why natural and sexual selection can be competing forms of selection and give an example from lecture (20pts).
Natural selection favors traits in individuals that lead to an organisms becoming better adapted to their environment. Sexual selection will often produce large ornaments that favor males in the context of female choice. Such ornaments invariably lead to a survival cost, which causes decreased fitness. Thus, ornaments would not be favored by natural selection, but are strongly favored by sexual selection. Ornaments have no benefit for the organisms in the context of environmental adaptation. An example would include color in fish, which makes guppies attractive to both females of the same species, and to predators!
2. Address the nature versus nuture debate using the question of I.Q.
heritability (20pts).
"Nature versus nature": are the behaviors a product of the organisms genetic
background, or their environment? From an analysis of IQ it is clear that roughly 34% of the variation in IQ is due to additive genetic causes. However, the identified enviromental factors such as maternal womb environment (5-20%) and the common household environment (17%) during rearing together total 22-37%, nearly the same as additive genetic factors. Needless, to say, considerable room for improvement in human IQ should rely on attention to pre-natal and post-natal environmental factors. There are also many unidentified environmental factors over and above this 22-37%.
Thus, it is not just nature or just nurture, but a complex interaction between both factors!