The Elements of Evolution (43-6-1) Backdoor Beetles

 Backdoor Beetles

Male coastal dung beetles develop extravagant weaponry in the form of horns or enlarged mandibles. They employ these armaments during combat over females, protecting the entrance to tunnels where the lady of the household resides. The horniest male beetle almost always triumphs.

At some point, the biological cost of built-in armory becomes too expensive. So it is with the coastal dung beetle. Their horns may make up 30% of body weight.

Because nutrients are shifted to horn growth, males with stunning racks may have stunted eye growth and tiny testicles. The cost is so high for coastal dung beetles that only a relative few males have competitive horns.

An adaptive alternative arose: cheat. Some male coastal dung beetles stay relatively small and grow no horns. Instead, they are vested with terrific testes that produce extraordinary amounts of sperm.

Sans fighting weapons, these nimble dung beetles dig backdoor tunnels, where they charm the female within while the brute at the den entrance is none the wiser. Ninja lovers do not mate as many females as the larger beetles, but they make the most of every opportunity.

For male coastal dung beetles, there are 2 ways to have the equipment where it counts.