Sometimes it seems that men and women are completely different. A lot of the times they are. We all know the physical differences between men and women in humans, but also the peacock is a good example in which the male has a large bright tail which he shows off to all the ladies, while the female is plain brown with a normally sized tail (see the picture below). These differences between male and female peacocks are caused by sexual selection.
The differences in the peacock are very clear, but when we look closely we can also find differences between the sexes in insects. More specifically, when a structure evolves to further the advantage of one sex at the expense of the other sex we call it “sexual antagonism”. Recently, Khila et al. (2012) published about just such a trait in the waterstrider (Rheumatobates rileyi). In this species it is very hard for males to get females to mate (isn’t it always?). The females struggle vigorously to reject male mating attempts. But these males are no quitters; they evolved very special antennae to overcome the female resistance. Contrary to the female antennae, male antennae evolved to be shaped wrench like, able to grasp something. Furthermore, in their wrench like antennae they have 3 more structures adapted for grasping; a hook, a spike, and a pad (see the awesome figure below!).
I want to thank Abderrahman Khila for providing me with these cool pictures to add to my post!
You can find the full story in Science here: