Department of Biological Sciences, Florida State University, 319 Stadium Drive, Tallahassee, FL 32304, USA.
Department of Biology and Ecology of Fishes, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany.
Proc Biol Sci. 2022 Jul 13;289(1978):20220731. doi: 10.1098/rspb.2022.0731.
Understanding how individual differences arise and how their effects propagate through groups are fundamental issues in biology. Individual differences can arise from indirect genetic effects (IGE): genetically based variation in the conspecifics with which an individual interacts. Using a clonal species, the Amazon molly (), we test the hypothesis that IGE can propagate to influence phenotypes of the individuals that do not experience them firsthand. We tested this by exposing genetically identical Amazon mollies to conspecific social partners of different clonal lineages, and then moving these focal individuals to new social groups in which they were the only member to have experienced the IGE. We found that genetically different social environments resulted in the focal animals experiencing different levels of aggression, and that these IGE carried over into new social groups to influence the behaviour of naive individuals. These data reveal that IGE can cascade beyond the individuals that experience them. Opportunity for cascading IGE is ubiquitous, especially in species with long-distance dispersal or fission-fusion group dynamics. Cascades could amplify (or mitigate) the effects of IGE on trait variation and on evolutionary trajectories. Expansion of the IGE framework to include cascading and other types of carry-over effects will therefore improve understanding of individual variation and social evolution and allow more accurate prediction of population response to changing environments.
理解个体差异是如何产生的，以及它们的影响如何在群体中传播，是生物学中的基本问题。个体差异可能源于间接遗传效应（IGE）：个体与之相互作用的同种生物之间基于遗传的变异。我们使用克隆物种——亚马逊神仙鱼（Poecilia formosa）来检验 IGE 是否可以传播，从而影响那些没有直接经历过 IGE 的个体的表型这一假设。我们通过将遗传上相同的亚马逊神仙鱼暴露于具有不同克隆谱系的同种社会伙伴中，然后将这些焦点个体转移到新的社会群体中，在新的社会群体中，它们是唯一经历过 IGE 的个体，从而测试了这一点。我们发现，不同的遗传社会环境导致焦点动物经历不同程度的攻击，而这些 IGE 会延续到新的社会群体中，影响天真个体的行为。这些数据表明，IGE 可以在经历它们的个体之外级联。IGE 级联的机会无处不在，尤其是在具有远距离扩散或裂变融合群体动态的物种中。级联可以放大（或减轻）IGE 对特征变异和进化轨迹的影响。因此，将 IGE 框架扩展到包括级联和其他类型的延续效应，将有助于更好地理解个体变异和社会进化，并更准确地预测种群对环境变化的反应。
