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
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This study 's findings, while interesting - males with more complex copulatory courtship behaviours being more likely to influence female choice – may not be entirely accurate. Shuker et al. defined their measures of success as "copulation duration and mount duration" (2002); as outlined by Eberhard, these events do not necessarily signify fertilization (1994). However, Shuker et al. performed another interesting experiment with respect to copulation duration and the timing of insemination in P. viridicoeruleus. By freezing and dissecting females at various points during copulation, they provided support for the idea that behaviours they associated with copulatory courtship continue after sperm transfer has occurred, and are therefore unrelated to intromission (2002). Tallamy et al. also chose to dissect female cucumber beetles in order to observe their genitalia. As previously mentioned, this group found that males that stopped stroking their mates during copulation were successful in transferring their spermatophore. Upon dissecting females whose mates had finished stroking, it was observed that sperm could be transferred to the spermatheca, such that fertilization could occur. In comparison, females whose mates had not finished stroking would only allow for sperm to be deposited in …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
This study 's findings, while interesting - males with more complex copulatory courtship behaviours being more likely to influence female choice – may not be entirely accurate. Shuker et al. defined their measures of success as "copulation duration and mount duration" (2002); as outlined by Eberhard, these events do not necessarily signify fertilization (1994). However, Shuker et al. performed another interesting experiment with respect to copulation duration and the timing of insemination in P. viridicoeruleus. By freezing and dissecting females at various points during copulation, they provided support for the idea that behaviours they associated with copulatory courtship continue after sperm transfer has occurred, and are therefore unrelated to intromission (2002). Tallamy et al. also chose to dissect female cucumber beetles in order to observe their genitalia. As previously mentioned, this group found that males that stopped stroking their mates during copulation were successful in transferring their spermatophore. Upon dissecting females whose mates had finished stroking, it was observed that sperm could be transferred to the spermatheca, such that fertilization could occur. In comparison, females whose mates had not finished stroking would only allow for sperm to be deposited in …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