Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn TR10 9EZ, Cornwall, UK.
Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley 6009, Western Australia, Australia.
Proc Biol Sci. 2021 Aug 11;288(1956):20211069. doi: 10.1098/rspb.2021.1069. Epub 2021 Aug 4.
Conditional strategies occur when the relative fitness pay-off from expressing a given phenotype is contingent upon environmental circumstances. This conditional strategy model underlies cases of alternative reproductive tactics, in which individuals of one sex employ different means to obtain reproduction. How kin structure affects the expression of alternative reproductive tactics remains unexplored. We address this using the mite , in which large males develop into aggressive 'fighters' and small males develop into non-aggressive 'scramblers.' Because only fighters kill their rivals, they should incur a greater indirect fitness cost when competing with their relatives, and thus fighter expression could be reduced in the presence of relatives. We raised mites in full-sibling or mixed-sibship groups and found that fighters were more common at higher body weights in full-sibling groups, not less common as we predicted (small individuals were almost exclusively scramblers in both treatments). This result could be explained if relatedness and cue variability are interpreted signals of population density, since fighters are more common at low densities in this species. Alternatively, our results may indicate that males compete more intensely with relatives in this species. We provide the first evidence of kin-mediated plasticity in the expression of alternative reproductive tactics.
当表达给定表型的相对适合度取决于环境情况时，就会出现条件策略。这种条件策略模型是替代生殖策略的基础，其中一种性别的个体采用不同的手段来获得繁殖。亲属结构如何影响替代生殖策略的表达仍未被探索。我们使用螨类来解决这个问题，在螨类中，大雄性发育成攻击性的“斗士”，小雄性发育成非攻击性的“抢夺者”。因为只有斗士会杀死它们的竞争对手，所以当它们与亲属竞争时，它们会遭受更大的间接适合度成本，因此，在有亲属的情况下，斗士的表达可能会减少。我们在全同胞或混合同胞群体中饲养螨类，发现斗士在全同胞群体中的体重较高时更为常见，而不是我们预测的较少（在两种处理方式中，小个体几乎都是抢夺者）。如果将亲缘关系和线索变异性解释为种群密度的信号，那么这个结果是可以解释的，因为在这个物种中，斗士在低密度时更为常见。或者，我们的结果可能表明，在这个物种中，雄性与亲属的竞争更为激烈。我们提供了亲属介导的替代生殖策略表达可塑性的第一个证据。
