RISE OF FEMALE WEAPONRY DRIVEN BY POOP FIGHTS

That's right I said,"Poop" Females of the species Onthophagus sagittarius who had heftier horns won control of more available dung and thus laid more eggs. Researchers have often wondered the origins of females and horns in animals. Males have horns to compete for females. But females have remained a mystery in some species. Many females, especially in bovines have small horns to ward off enemies. While others have been speculated to be a genetic spill over from the males. But in case of this dung beetle, the horns are different then the males in placement and size. That's because they are for a different purpose. In lab tests, female beetles with larger horn were able to wrangle larger plots of "poop" to lay eggs. So from a evolution standpoint, the smaller horned beetles cannot produce as many eggs and in turn have less of a chance for survival.

http://www.sciencenews.org/view/generic/id/56846/title/Rise_of_female_weaponry_driven_by_poop_fights