De Gasperin Ornela, Duarte Ana, Kilner Rebecca M
Department of Zoology, University of Cambridge, Cambridge, U.K.
Anim Behav. 2015 Nov;109:199-207. doi: 10.1016/j.anbehav.2015.08.014.
Why is there so much variation within species in the extent to which males contribute to offspring care? Answers to this question commonly focus on intraspecific sources of variation in the relative costs and benefits of supplying paternal investment. With experiments in the laboratory on the burying beetle, , and its phoretic mite , we investigated whether interactions with a second species might also account for intraspecific variation in the extent of paternal care, and whether this variation is due to adaptation or constraint. In our first experiment we bred beetles in the presence or absence of phoretic mites, using a breeding box that mimicked natural conditions by allowing parents to leave the breeding attempt at a time of their choosing. We found that males abandoned their brood sooner when breeding alongside mites than when breeding in their absence. Female patterns of care were unchanged by the mites. Nevertheless, in this experiment, no correlates of beetle fitness were affected by the presence of the mites during reproduction (neither paternal life span after reproduction nor brood size or average larval mass). In a second experiment, we again bred beetles with or without mites but this time we prevented parents from abandoning the brood. This time we found that both parents and the brood suffered fitness costs when breeding alongside mites, compared with families breeding in the absence of mites. We conclude that males adaptively reduce their contributions to care when mites are present, so as to defend their offspring's fitness and their own residual fitness. Interspecific interactions thus account for intraspecific variation in the duration of paternal care.
为什么在雄性对后代照料的贡献程度上,物种内部会存在如此大的差异?对这个问题的回答通常集中在种内变异的来源上,即提供父本投资的相对成本和收益。通过在实验室对埋葬甲虫及其携带的螨类进行实验,我们研究了与第二个物种的相互作用是否也能解释父本照料程度的种内变异,以及这种变异是由于适应还是限制。在我们的第一个实验中,我们在有或没有携带螨类的情况下饲养甲虫,使用一个模拟自然条件的繁殖箱,允许亲本在它们选择的时间离开繁殖尝试。我们发现,与没有螨类时相比,雄性在与螨类一起繁殖时更快地抛弃了它们的幼崽。螨类对雌性的照料模式没有影响。然而,在这个实验中,繁殖期间螨类的存在并没有影响甲虫适合度的相关因素(繁殖后父本的寿命、幼崽数量或平均幼虫质量)。在第二个实验中,我们再次在有或没有螨类的情况下饲养甲虫,但这次我们阻止亲本抛弃幼崽。这一次我们发现,与没有螨类时繁殖的家庭相比,与螨类一起繁殖时,亲本和幼崽都遭受了适合度成本。我们得出结论,当有螨类存在时,雄性会适应性地减少它们对照料的贡献,以保护它们后代的适合度和自己的剩余适合度。因此,种间相互作用解释了父本照料持续时间的种内变异。