Chapter 7

A recent experimental study by Bro-Jorgensen et al. (2007) suggests that variation in tail length in barn swallows reflects natural selection, because the aerodynamically optimal tail length varies significantly between males. How might this complicate the interpretation of long tails as a sexually selected ornament?

Why in some species do males compete for females by force while in others they do so by charm? Discuss the factors that might lead to one form of competition rather than the other.