Rapid local adaptation linked with phenotypic plasticity

Models of ‘plasticity-first’ evolution are attractive because they explain the rapid evolution of new complex adaptations. Nevertheless, it is unclear whether plasticity can facilitate rapid microevolutionary change between diverging populations. Here we show how plasticity may have generated adaptive differences in fecundity between neighbouring wild populations of burying beetles Nicrophorus vespilloides. These populations occupy distinct Cambridgeshire woodlands that are just 2.5km apart and that probably originated from a common ancestral population c. 1000-4000 years ago. We find that populations are divergently adapted to breed on differently-sized carrion. Adaptive differences in clutch size and egg size are associated with divergence at loci connected with oogenesis. The populations differ specifically in the elevation of the reaction norm linking clutch size to carrion size (i.e. genetic accommodation), and in the likelihood that surplus offspring will be lost after hatching. We suggest that these two processes may have facilitated rapid local adaptation on a fine-grained spatial scale.

“‘塑性优先’演化模型颇具吸引力，因其可解释全新复杂适应性性状的快速演化。然而目前仍无法确定，表型塑性能否推动分化种群间发生快速的微演化改变。本研究揭示，表型塑性可能促成了邻近埋葬甲（Nicrophorus vespilloides）野生种群间繁殖力的适应性分化。这些种群栖息于剑桥郡两处相距仅2.5公里的独特林地，其祖先种群大概率可追溯至约1000至4000年前的同一始祖种群。研究发现，这些种群已演化出对不同大小腐肉的歧化适应性繁殖策略：窝卵数与卵大小的适应性差异，与卵子发生相关基因座的遗传分化存在关联。具体而言，两类种群在联结窝卵数与腐肉大小的反应规范高度（即遗传顺应）上存在差异，同时在孵化后过剩后代被淘汰的概率上亦有所不同。我们推测，这两种过程可能推动了精细空间尺度下的快速局部适应性演化。