Department of Evolutionary Animal Ecology, University of Bayreuth, Bayreuth, DE-95440, Germany.
Evolution. 2022 Feb;76(2):320-331. doi: 10.1111/evo.14414. Epub 2022 Jan 3.
The widely spread evolutionary strategy of parental care is considered an important driver of social evolution. Although offspring were long thought to primarily interact competitively, recent studies revealed the potential importance of sibling cooperation. Theories suggest that the degree of cooperation in offspring interactions depends on the degree of offspring dependence on parental care: offspring unable to forage on their own should compete more, whereas more independent juveniles may increase the degree of cooperation. In this study, we tested the occurrence of sibling cooperation in the absence of posthatching care in several burying beetle species exhibiting varying degrees of offspring dependence. To this end, we measured larval growth rate and survival in the presence and absence of prehatching care using different brood sizes. We found that sibling cooperation cannot be exclusively explained by offspring dependence on parental care. Although only species with more independent larvae cooperated when receiving prehatching care, larval cooperation occurred across species in the absence of care. The latter result suggests that sibling cooperation was already present in an early ancestor of the genus Nicrophorus. Overall, these findings give important insights into the transition from facultative to obligate family life.
亲代照顾的广泛传播进化策略被认为是社会进化的重要驱动力。尽管长期以来人们认为后代主要是相互竞争的，但最近的研究揭示了兄弟姐妹合作的潜在重要性。理论表明，后代相互作用的合作程度取决于后代对亲代照顾的依赖程度：不能自行觅食的后代应该竞争更多，而更独立的幼崽可能会增加合作程度。在这项研究中，我们在没有孵化后照顾的情况下，在表现出不同程度后代依赖的几种埋葬甲虫物种中测试了兄弟姐妹之间的合作。为此，我们使用不同的巢大小来衡量存在和不存在孵化前照顾的幼虫生长率和存活率。我们发现，兄弟姐妹之间的合作不能仅仅用后代对亲代照顾的依赖来解释。尽管只有那些幼虫更独立的物种在接受孵化前照顾时才会合作，但在没有照顾的情况下，幼虫在不同物种中都存在合作。后一种结果表明，兄弟姐妹合作已经存在于 Nicrophorus 属的早期祖先中。总的来说，这些发现为从偶然到必需的家庭生活的转变提供了重要的见解。
