A plains mouse (Pseudomys australis) Roland Seitre/Minden Footage/Alamy
Male rodents with shorter breeding seasons are likely to have bigger testes, most likely as a result of the time strain will increase sperm competitors between males.
Research have discovered that males sometimes have larger testes when the females of their species have a number of mating companions. It’s because their sperm should compete inside the feminine reproductive tract to fertilise the eggs, that means it’s advantageous to have larger testes that may produce extra sperm.
“It’s like a raffle – the extra tickets you have got, the extra seemingly you’re to win,” …
