Chamorro-Florescano Ivette A, Favila Mario E, Macías-Ordóñez Rogelio
Facultad de Ciencias Biológicas y Agropecuarias, Universidad Veracruzana, Tuxpan, Veracruz, Mexico.
Red de Ecoetología, Instituto de Ecología A.C., Xalapa, Veracruz, Mexico.
PLoS One. 2017 Aug 10;12(8):e0182931. doi: 10.1371/journal.pone.0182931. eCollection 2017.
Fights among females are frequent, although less attention has been placed on them than on male fights. They arise when females compete for food, oviposition, mates, brooding sites, or access to resources which increase offspring survival. It has been shown that the outcome of female fights may be less predictable by asymmetries in resource holding power, than in male fights. Male roller beetles fight over food resources, food balls, needed for mating and nesting, and it has been show in some species that asymmetries in reproductive experience and resource holding power in terms of size predict fight outcome, including ties in which contenders cut and split the food ball. In this study, we tested the influence of asymmetries in reproductive status (experience) and body size on female fight outcome in the carrion roller beetle Canthon cyanellus cyanellus. As predicted, and as previously found for males of the same species, female reproductive status of both contenders and relative size predict fight outcome. Larger and reproductively experienced contenders have a higher probability of winning. Furthermore, ties are more likely in fights involving opposing asymmetries (vgr. Large reproductively naïve owner versus small reproductively experienced intruder). Also as predicted, food ball splitting is more likely to be started by the predicted loser. This mode of resource sharing may be the result of a fighting strategy in which the costs of continuing to fight are greater than the benefits of not splitting, if a fraction of the disputed resource is more than the minimum needed for the present reproductive needs, and reduces costs associated to a longer fight.
雌性之间的争斗很频繁，尽管与雄性争斗相比，人们对其关注较少。当雌性为食物、产卵地、配偶、育雏地点或获取能提高后代存活率的资源而竞争时，就会发生争斗。研究表明，与雄性争斗相比，雌性争斗的结果可能较难通过资源占有能力的不对称性来预测。雄性蜣螂会为交配和筑巢所需的食物资源——食物球而争斗，并且在一些物种中已经表明，生殖经验和体型方面的资源占有能力不对称性能够预测争斗结果，包括竞争者切割并分割食物球的平局情况。在本研究中，我们测试了生殖状态（经验）和体型的不对称性对食腐蜣螂Canthon cyanellus cyanellus雌性争斗结果的影响。正如预测的那样，并且如之前在同一物种的雄性中所发现的，争斗双方的雌性生殖状态和相对体型能够预测争斗结果。体型较大且有生殖经验的竞争者获胜概率更高。此外，在涉及相反不对称性的争斗中（例如，生殖上无经验的大体型所有者与生殖上有经验的小体型入侵者），平局的可能性更大。同样如预测的那样，食物球分割更有可能由预测的失败者发起。这种资源共享模式可能是一种争斗策略的结果，即如果有争议资源的一部分超过当前生殖需求所需的最小值，继续争斗的成本大于不分割的收益，并且这种模式能降低与长时间争斗相关的成本。
