Data from: Iterative development and the scope for plasticity: contrasts among trait categories in an adaptive radiation

Phenotypic plasticity can influence evolutionary change in a lineage, ranging from facilitation of population persistence in a novel environment to directing the patterns of evolutionary change. As the specific nature of plasticity can impact evolutionary consequences, it is essential to consider how plasticity is manifested if we are to understand the contribution of plasticity to phenotypic evolution. Most morphological traits are developmentally plastic, irreversible, and generally considered to be costly, at least when the resultant phenotype is mis-matched to the environment. At the other extreme, behavioral phenotypes are typically activational (modifiable on very short time scales), and not immediately costly as they are produced by constitutive neural networks. Although patterns of morphological and behavioral plasticity are often compared, patterns of plasticity of life history phenotypes are rarely considered. Here we review patterns of plasticity in these trait categories within and among populations, comprising the adaptive radiation of the threespine stickleback fish Gasterosteus aculeatus. We immediately found it necessary to consider the possibility of iterated development, the concept that behavioral and life history trajectories can be repeatedly reset on activational (usually behavior) or developmental (usually life history) time frames, offering fine tuning of the response to environmental context. Morphology in stickleback is primarily reset only in that developmental trajectories can be altered as environments change over the course of development. As anticipated, the boundaries between the trait categories are not clear and are likely to be linked by shared, underlying physiological and genetic systems.

表型可塑性（phenotypic plasticity）可影响谱系内的演化变化，其效应范围涵盖促进种群在新环境中的存续，乃至主导演化变化的模式。由于可塑性的具体特性会影响演化结局，若要阐明表型可塑性对表型演化的贡献，就必须考量可塑性的具体表现形式。多数形态性状（morphological traits）具有发育可塑性且不可逆，通常被认为具有适应性代价——至少当由此产生的表型与环境不匹配时如此。而行为性状（behavioral phenotypes）则处于另一极端：其通常属于激活型可塑性（可在极短时间尺度内被修饰），且不会立即产生适应性代价，因为它们由组成型神经网络（constitutive neural networks）调控产生。尽管学界常对比形态与行为可塑性的模式，但生活史性状（life history phenotypes）的可塑性模式却极少被纳入研究范畴。本文以三棘刺鱼（Gasterosteus aculeatus）的适应辐射（adaptive radiation）类群为研究对象，综述了各类群内及类群间上述三类性状的可塑性模式。我们随即意识到有必要考量“重复发育（iterated development）”这一概念：即行为与生活史轨迹可分别在激活型（通常对应行为调控）或发育型（通常对应生活史调控）的时间尺度上被反复重置，从而实现对环境背景响应的精细调控。刺鱼的形态可塑性仅在有限层面可被重置：即发育轨迹可随发育进程中环境的变化而发生改变。正如预期，不同性状类别的界限并不明晰，且很可能通过共享的底层生理与遗传系统实现关联。