5/30/2023 0 Comments Definition of choosySome types of nuptial gifts are considered a direct benefit, because they enhance a female’s survival and reproduction. However, if a female bites the head off a male after copulation has been initiated, mating typically continues until sperm is transferred. Females will bite off the head of males, sometimes before even mating with them. The most popular example of sexual cannibalism is in mantids. However, the high prevalence of sexual cannibalism in several species of spiders gave rise to the common name “black widow spider”. In any event, this type of sexual behavior is quite rare because the costs are often assumed to out-weigh the benefits, particularly for males. Some suggest that males that submit to females and are cannibalized gain a selective advantage by producing higher quality offspring. Experiments show that females on low quality diets are more likely to cannibalize her mates, compared with females given high quality diets. The reason for sexual cannibalism has been heavily debated. Because copulatory movement in males is controlled by nerves in the abdomen, not the head, removal of a male’s head does not affect mating, sperm transfer, or proper fertilization. Most often, a female mantid will begin feeding by biting off the head of a male, as they would with regular prey. Most predatory species of preying mantids practice a type of extreme nuptial feeding known as sexual cannibalism, in which a female will eat her mate prior to, during, or after copulation. For example, in some species of ground crickets, females receive a nuptial gift by chewing on a specialized spur structure on the male hind tibia (i.e. In extreme cases, males will even sacrifice parts or all of themselves to females. In this way the size or quality of the nuptial gift can serve as another trait through which females can judge the quality of a potential mate. Such is the case in many insects and spiders where males present these nuptial food gifts to females in the hopes that she will choose to mate with him. A female great grey shrike will choose a mate according to the size of the prey item presented to her. For example, male great grey shrikes- a predatory bird- will present prey items like rodents, other birds, lizards, and large insects to females immediately before mating. These resources, called nuptial gifts, provide nourishment to females that they may not otherwise get. Males will sometimes provide females with a food gift before mating. Direct benefits increase the fitness of choosy individuals through material resources. Broadly, there are two types of fitness benefits that drive mate choice: direct and indirect benefits. How do females decide whether a male is a suitable mate? There are several, non-exclusive models of how and why mating preferences evolve. A female simply has more to lose by making a bad choice about her mate. Therefore, females have a vested interest in protecting their eggs from males who are less fit. As we discussed above, the difference in gamete size and production predicts that females should be choosy about whom they mate with because eggs are costlier to produce than sperm.
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