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.

隐蔽进化（cryptic evolution）是指进化变化被同步发生的环境变化所遮蔽的演化现象。多数情况下，表型（phenotype）的进化变化会被不断变化的非生物因子所遮蔽。然而，某一性状的进化变化也可能被另一性状的进化变化所遮蔽，这一现象被称为进化性环境恶化（evolutionary environmental deterioration）。尽管如此，检测这类第二类型的隐蔽进化仍颇具挑战，目前令人信服的相关案例寥寥无几。本研究中，我们描述了一个可能发生进化性环境恶化的实验案例：实验对象为埋葬甲（Nicrophorus vespilloides）种群，它们正适应一种缺乏孵化后双亲抚育的全新社会环境。我们发现，该种群快速适应了移除孵化后双亲抚育的环境。这种适应表现为繁殖成功率和幼虫密度（每克繁殖尸体重所产生的扩散幼虫数量）显著提升，而这一变化反过来遮蔽了跨世代平均幼虫体重的同步增长。这种幼虫体重的隐蔽增长，是通过改变将平均幼虫体重与幼虫密度关联起来的反应规范（reaction norm）实现的。我们的研究结果表明，隐蔽进化在动物类群中可能相当普遍，因为不断演化的营养与社会互动关系，有可能遮蔽诸如体型这类其他性状的进化变化。