Seminar Two
Evolution of sexuality
Sexual behavior in nature

Lions break the rules.

A consorting lion and lioness in the Serengeti-Mara typically mate every fifteen minutes for three days. If she walks away from him, he follows her. Is he playfully biting at her tail, as shown above?

We naively thought so at first, then realized that he is really flehmening, sampling the airborne molecules with which she advertises her mating readiness. At the moment of climax, he grimaces and she roars at him, at which point he dismounts and she rolls over onto her back.

Lions are highly social,living in prides. Prides consist of related females, their cubs, and unrelated males who have taken over the pride after ousting the previous adult males. A takeover by a new male coalition is dangerous for young cubs, which are often killed by the new males. This behavior brings the females into estrus and allows the new males to mate sooner.

A lioness is choosy with whom she mates. She may repel advances and may even court males outside of her pride. One study in the Serengeti found that a female delays her ovulation for up to one hundred days after beginning to mate with different males before committing her eggs to fertilization. Why might she do this?

One hypothesis is that she is taking a look at outside males and evaluating the risk of a takeover by a new male coalition, in order not to waste her resources on cubs fathered by current pride males. If genes arise which predispose to this behavior, and if she enjoys a net improvement in her reproductive success as a result, those alleles (variations of a gene) may outcompete other alleles of the same genes and spread in future generations. The behavioral predisposition, or proclivity, would be coded for in her genome. We are not speaking of conscious behavior or insight on her part, only behavioral predispositions.