Importance Of Sexual Selection

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Darwin’s second observation was that of sexual selection (Hosken & House, 2011). Sexual selection selects for traits that make an individual more successful in finding a mate and producing offspring (Kansehiro, 2009). Most often, this type of selection involves males (Hosken & House, 2011). A prominent example of a male trait that is subject to sexual selection is courtship behaviour (Eberhard, 1994). Courtship allows mates (most often females) to gain information about the quality of their potential mate, and often involves displays, or the giving of “gifts”, often in the form of nutrients (“Courtship”, 1998). These behaviors have been observed in many different types of animals, including insects. Courtship has been studied …show more content…
C. maculatus is a sexually dimorphic seed beetle, with females having a larger body size than that of males (Savalli & Fox, 1999). Despite their small size, males are known to have relatively large ejaculates, which act as a source of resources for their mates (Edvardsson, 2007). Although having access to these nutrients provided by their mates is of benefit to the females, it appears that living in the presence of males is costly to female C. maculatus health. Both females who were provided nutrients and those who were nutrient depleted had a shorter lifespan when housed with males, due to the cost of mating and being chased by males. Savalli and Fox also investigated the effects of several variables on mating success, including male size, age, experience and persistence on mating success. It was found that the only factor that increased mating success for males was large body size (due to competition between males), and that virgin females weren’t particularly selective about their mates. This came as a surprise, as mating can be quite costly for female C. maculatus (1999), since the males’ intromittent organs can cause significant internal damage to their mates during copulation. There is apparently no benefit for male reproductive success as a result of harming the females. It has been postulated that the barbs simply evolved as an anchoring device, and that the damage caused to the female genital tract is an unfortunate side effect (Edvardsson & Tregenza, 2005). However, reproduction is not without costs to male C. maculatus, as transferring such a nutrient risk ejaculate can be costly to the males. In fact, ejaculate size has been shown to reduce with successive matings. This result is significant because the life history of her mate may have implications for a female’s fecundity. Females that mate with only virgin males receive more ejaculate

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