Sexual selection and mate choice

It is reasonable to expect that males and females of a species have evolved behavioral traits related to mate choice that maximize their fitness in reproductive terms. In the case of elephants, consider the following aspects of social organization and physiology. As with other mammalian species, the females spend more energy directly in reproduction compared to males. In a polygy-nous society with an absence of male parental care, this difference between the sexes in costs of reproduction and rearing of offspring is even more accentuated. Given the long gestation period in elephants, less than a third of females in a population can potentially come into estrus at a given time. Females, however, come into estrus on average only every 15 weeks or so, and estrus lasts for only 3-7 days. It thus makes sense for a male to search actively for as many estrous females as possible rather than try to defend a harem. Once an estrous female is located, a male would normally have to compete with other males before successfully mating.

Male elephants have thus evolved traits that allow them to compete with other males as well as attract the attention of several estrous females. Potentially, a male could evolve honest signals of motivation in competing with rival males or cheat about its real motivational state. Similarly, a male could honestly advertise its true quality to potential mates or cheat about its inherent status. In theory, there could also be some form of mate choice by males. Among elephants, there is certainly much individual recognition given the longevity of the species. The issue of mate choice by males is probably a relatively trivial one among elephants (except to avoid inbreeding) as it would pay for a male elephant to copulate with as many estrous females as possible. This subject, however, is open to further study.

The female elephant, on the other hand, is better off by choosing the fittest male from the pool of males she attracts. A wrong choice of a mate would be expensive for the female as her offspring could be less fit if sired by an inferior male. She should thus be able to discriminate among her suitors, see through dishonest male signals, and recognize honest signals of male quality.

Various traits and behaviors associated with reproduction will thus have to be examined for their adaptive roles in the mating game. Could musth have evolved in male elephants as a means of signaling their fighting ability or announcing their motivation in holding resources (estrous females)? What information do musth males convey to estrous females? How do these relate to the spacing of musth among males in a population? How is female choice of mates influenced by musth and potential sexual ornamentation, such as tusks, in elephants?

0 0

Post a comment