BIO318Y5 Lecture Notes - Parental Investment
Document Summary
Why are female battles rare? (why males are more gorgeous) Long tailed dance flies: females form swarms shaped like a disk. Females breathe air to inflate their abdomen to look like they have lots of eggs. Males come from under the females to select the females who have the most eggs (from the size of their abdomen) females eat the insects which the males bring to them. Therefore, females are being strongly sexually selected on. But being big is not so anti-survival because although females are more likely to be caught in spider webs than males, bigger females are also more likely to escape! Competition is about something that is in short supply. Females are in short supply because they are raising offspring + have to eat more to feed zygote. Less females available for mating than males => sexual selection => sexual differences. Therefore the skewed sex ratio causes the competition.
