Data from: Adaptation to a novel family environment involves both apparent and cryptic phenotypic changes

Cryptic evolution occurs when evolutionary change is masked by concurrent environmental change. In most cases, evolutionary changes in the phenotype are masked by changing abiotic factors. However, evolutionary change in one trait might also be masked by evolutionary change in another trait, a phenomenon referred to as evolutionary environmental deterioration. Nevertheless, detecting this second type of cryptic evolution is challenging and there are few compelling examples. Here, we describe a likely case of evolutionary environmental deterioration occurring in experimental burying beetle (Nicrophorus vespilloides) populations that are adapting to a novel social environment that lacks post-hatching parental care. We found that populations rapidly adapted to the removal of post-hatching parental care. This adaptation involved clear increases in breeding success and larval density (number of dispersing larvae produced per gram of breeding carcass), which in turn masked a concurrent increase in the mean larval mass across generations. This cryptic increase in larval mass was accomplished through a change in the reaction norm that relates mean larval mass to larval density. Our results suggest that cryptic evolution might be commonplace in animal families, because evolving trophic and social interactions can potentially mask evolutionary change in other traits, like body size.

隐蔽演化（Cryptic evolution）是指演化变化被同步发生的环境变化所掩盖的现象。多数情况下，物种表型（phenotype）的演化变化会被持续变化的非生物因子（abiotic factors）所掩盖。然而，某一性状的演化变化也可能被另一性状的演化变化所掩盖，这一现象被称为演化性环境恶化（evolutionary environmental deterioration）。尽管如此，检测这类隐蔽演化仍颇具挑战，且目前鲜有令人信服的实证案例。本研究描述了一例可能发生演化性环境恶化的案例，其研究对象为正在适应缺乏孵化后亲代抚育（post-hatching parental care）的新型社会环境的斑埋葬甲（Nicrophorus vespilloides）实验种群。研究发现，该种群可快速适应孵化后亲代抚育的移除。这种适应过程伴随着繁殖成功率与幼虫密度（larval density，每克繁殖用腐尸产生的扩散幼虫数量）的显著提升，而这两者又掩盖了世代间幼虫平均体重的同步增长。这种幼虫体重的隐蔽增长，是通过改变幼虫平均体重与幼虫密度间关联的反应规范（reaction norm）实现的。本研究结果表明，隐蔽演化在动物类群中可能颇为常见，因为演化中的营养与社会互作（trophic and social interactions）有可能掩盖其他性状（如体型）的演化变化。