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Sexual selection in spiders shows how sexual selection explains the evolution of phenotypic traits in spiders.〔Buss, D. M. The evolution of human intrasexual competition: tactics of mate attraction. Journal of personality and social psychology 54, 616–28 (1988).〕 Male spiders have many complex courtship rituals and have to avoid being eaten by the females, with the males of most species survive a few matings, and having short life spans. Pre-copulatory mate choice processes have been observed in a wide range of spider species, including ''Stegodyphus lineatus, Argiope aurantia, Schizocosa floridana, Hygrolycosa rubrofasciata, and Schizocosa stridulans''.〔Maklakov, A. a., Bilde, T. & Lubin, Y. Sexual selection for increased male body size and protandry in a spider. Animal Behaviour 68, 1041–1048 (2004).〕〔Foellmer, M. W. & Fairbairn, D. J. Competing dwarf males: sexual selection in an orb-weaving spider. Journal of evolutionary biology 18, 629–41 (2005).〕〔Rosenthal, M. F. & Hebets, E. a. Resource heterogeneity interacts with courtship rate to influence mating success in the wolf spider Schizocosa floridana. Animal Behaviour 84, 1341–1346 (2012).〕〔〔 Sexual selection occurs after copulation as well as before copulation.〔Eberhard, W. G. Postcopulatory sexual selection: Darwin’s omission and its consequences. Proceedings of the National Academy of Sciences of the United States of America 106 Suppl , 10025–32 (2009).〕 Post-copulatory sexual selection involves sperm competition and cryptic female choice. Sperm competition occurs when the sperm of more than one male competes to fertilize the egg of the female. Cryptic female choice involves the expelling of a males sperm during or after copulations.〔Peretti, a V & Eberhard, W. G. Cryptic female choice via sperm dumping favours male copulatory courtship in a spider. Journal of evolutionary biology 23, 271–81 (2010).〕 ==Male to male competition== Size is a factor in the reproductive success of males with species such as ''Stegodyphus lineatus, Argiope aurantia and Argyroneta aquatica'' showing sexual dimorphism, beneficial for larger males, stronger and more aggressive, who fight off the smaller ones using their large chelicerae and forelegs.〔〔Tedore, C. & Johnsen, S. Weaponry, color, and contest success in the jumping spider Lyssomanes viridis. Behavioural processes 89, 203–11 (2012).〕 This leads to a decrease in the paternal success for smaller males since they are unable to gain access to females.〔Maklakov, A. a. & Lubin, Y. Indirect genetic benefits of polyandry in a spider with direct costs of mating. Behavioral Ecology and Sociobiology 61, 31–38 (2006).〕 In ''Argiope aurantia'' males can lose legs in combat, with the loss more prevalent in smaller maless, evidence that larger males arre favored in male-to-male competition.〔 In the water spider ''Argyroneta aquatica'', where males and females permanently live in the water〔Schutz, D. & Taborsky, M. Sexual Selection in the Water Spider: Female Choice and Male-Male Competition. Ethology 117, 1101–1110 (2011).〕 the males are larger, indicating sexual selective pressures for large body size. The large male water spiders are more mobile, helping them obtain more females. Sexual selection provides benefits to smaller male spiders under certain conditions, such as ''Misumena vatia'' and ''Nephila clavipes'', whose smaller males climb faster to reach their mates:〔Moya-Laraño, J., Vinković, D., Allard, C. M. & Foellmer, M. W. Optimal climbing speed explains the evolution of extreme sexual size dimorphism in spiders. Journal of evolutionary biology 22, 954–63 (2009).〕〔Moya-laraño, A. J., Halaj, J. & Wise, D. H. Climbing to Reach Females : Romeo Should be Small. 56, 420–425 (2001).〕 Explained by the gravity hypothesis,〔 outcompeting larger males thus having more reproductive success,〔 especially when females live in high patches of flowers,〔 whereas females live in low lying areas, larger males are favored.〔 In spiders like Tetragnathidae, Araneidae, Thomisidae and Pholicidae〔 there is an optimal body size that favors climbing speed. Smaller males will have an advantage over the largest males of the species, however the smallest male will not be the fastest climber.〔 This optimal body size for climbing is observed in different Males from the same species express phenotypes, weapons such as chelicerae, teeth or even legs to fight off competition are used to fight off oncoming rivals, with larger bodied spiders contained larger chelicerae.〔 In most cases body size correlated with mating success.〔 This isobserved in ''Lysommanes viridis'', whose males display weapons that are very pronounced in comparison with females and selected to help males fight off competition.〔 The time it takes to develop is crucial to the overall fitness of a spider. This idea is true, however does not mean that larger males will always have better fitness. In ''Latrodectus hasselti'', larger males outcompete smaller males by getting to the females web first. However, these large male spiders have long development times, meaning that the larger male will need more time before being able to copulate. Smaller males tend to have a quick development time which gives them an advantage in mating with a female. This advantage correlates with high paternal success in the species ''Latrodectus hasselti''. Larger males are able to outcompete smaller males, but not able to mate. Smaller males risk getting outcompeted, but are more likely to have paternal success.〔Kasumovic, M. M. & Andrade, M.C.B.A change in competitive context reverses sexual selection on male size. Journal of evolutionary biology 22, 324–33 (2009).〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sexual selection in spiders」の詳細全文を読む スポンサード リンク
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