Station d'Ecologie Expérimentale du CNRS à Moulis USR 2936, Moulis, 09200 Saint-Girons, France.
J Exp Biol. 2010 Mar 1;213(5):735-9. doi: 10.1242/jeb.040576.
Many organisms can adjust their phenotypes to match local environmental conditions via shifts in developmental trajectories, rather than relying on changes in gene frequencies wrought by natural selection. Adaptive developmental plasticity confers obvious benefits in terms of rapid response and higher mean fitness, so why is it not more common? Plausibly, adaptive plasticity also confers a cost; reshaping the phenotype takes time and energy, so that canalised control of trait values enhances fitness if the optimal phenotype remains the same from one generation to the next. Although this idea is central to interpreting the fitness consequences of adaptive plasticity, empirical data on costs of plasticity are scarce. In Australian tiger snakes, larger relative head size enhances maximal ingestible prey size on islands containing large prey. The trait arises via adaptive plasticity in snake populations on newly colonised islands but becomes genetically canalised on islands where snakes have been present for much longer periods. We experimentally manipulated relative head size in captive neonatal snakes to quantify the costs of adaptive plasticity. Although small-headed snakes were able to increase their head sizes when offered large prey, the delay in doing so, and their inability to consume large prey at the outset, significantly reduced their growth rates relative to conspecifics with larger heads at the beginning of the experiment. This study describes a proximate cause to the post-colonisation erosion of developmental plasticity recorded in tiger snake populations.
许多生物可以通过改变发育轨迹来调整表型以适应局部环境条件，而不是依赖自然选择引起的基因频率变化。适应性发育可塑性在快速反应和更高的平均适应度方面具有明显的优势，那么为什么它不更常见呢？合理地说，适应性可塑性也会带来代价；重塑表型需要时间和精力，因此如果最优表型在下一个世代保持不变，那么对特征值的管控制度会增强适应度。尽管这个想法是解释适应性可塑性的适应度后果的核心，但关于可塑性成本的经验数据却很少。在澳大利亚虎蛇中，相对较大的头部大小会增强在含有大型猎物的岛屿上可摄入的最大猎物大小。该特征通过新殖民岛屿上蛇种群的适应性可塑性产生，但在蛇类存在时间更长的岛屿上，该特征会在遗传上变得管控制度。我们通过在圈养的新生蛇中进行相对头部大小的实验操作，来量化适应性可塑性的成本。尽管小头蛇能够在提供大型猎物时增加其头部大小，但这样做的延迟以及它们一开始无法消耗大型猎物，使其相对于实验开始时头部较大的同种蛇的生长速度显著降低。这项研究描述了在虎蛇种群中记录到的殖民后发育可塑性侵蚀的一个近因。
