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Mating Decisions : Females And Females

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A number of factors play into the decision of one individual to mate with another, and in many species the females are the ones making these mating decisions. In terms of successfully reproducing, the number of offspring a male produces is limited by the number of females he gets to mate with, whereas females are limited by the amount of resources available to her. Thus, if males want to maximize the number of offspring they can produce they will choose to mate with those females who have access to the most resources and therefore are the most fertile. So, in a species dominated by male choice, research has suggested that males will tend to choose those females whose physical characteristics indicate high fertility. Those females who are…show more content…
It had previously been found that male guppies preferred larger females, because body size correlates with the number of eggs she is capable of producing, and thus is an indicator of her fertility. As a result, male guppies transfer more sperm to larger females, because it increases their chances of fathering the most offspring. For a male to be interested in mating with a particular female, the benefits of mating with her must outweigh the costs. The benefit of mating with a larger female, as opposed to a smaller female, is that there are more eggs to fertilize, thus the male would have more offspring, and a higher reproductive success. On the other hand, the cost of mating with a larger female is the increase in sperm competition that he would face. With this in mind, Jeswiet et al. sought to determine if male guppies were simultaneously able to assess both size and sperm competition in choosing a mate, thereby increasing their reproductive success, and whether the benefit of successfully mating with a female of larger size outweighed the cost of having to compete with other males to mate with her. They hypothesized that male guppies who saw females interacting with another male, would be less likely to pursue that female, and as the number of competing males increased, the male would become increasingly uninterested in that particular female because the costs of mating with her would outweigh the benefits. To test their hypotheses, adult
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