What we find is when you take into account seasonal changes in the population, it creates a scenario where there are two rounds of mate choice. A female that is choosing early has a different pool of available mates to choose from.
We've known awhile that in many species, females prefer the most extravagant and flashy males. We've also known that when individuals choose mates that are highly related to them, it's often a bad thing, leading to offspring of poor quality.