Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
Nat Ecol Evol. 2018 Aug;2(8):1289-1297. doi: 10.1038/s41559-018-0601-8. Epub 2018 Jul 9.
Plasticity-first evolution (PFE) posits that novel features arise when selection refines pre-existing phenotypic plasticity into an adaptive phenotype. However, PFE is controversial because few tests have been conducted in natural populations. Here we present evidence that PFE fostered the origin of an evolutionary novelty that allowed certain amphibians to invade a new niche-a distinctive carnivore morph. We compared morphology, gene expression and growth of three species of spadefoot toad tadpoles when reared on alternative diets: Scaphiopus holbrookii, which (like most frogs) never produce carnivores; Spea multiplicata, which sometimes produce carnivores, but only through diet-induced plasticity; and Spea bombifrons, which often produce carnivores regardless of diet. Consistent with PFE, we found diet-induced plasticity-in morphology and gene expression-in Sc. holbrookii, adaptive refinement of this plasticity in Sp. multiplicata, and further refinement of the carnivore phenotype in Sp. bombifrons. Generally, phenotypic plasticity might play a significant, if underappreciated, role in evolutionary innovation.
可塑性优先进化（PFE）假设，当选择将预先存在的表型可塑性精细调整为适应性表型时，新特征就会出现。然而，PFE 存在争议，因为在自然种群中进行的测试很少。在这里，我们提供了证据表明 PFE 促进了一种进化新颖性的出现，这种新颖性使某些两栖动物能够入侵一个新的生态位——一种独特的肉食形态。我们比较了三种铲足蟾蜍蝌蚪在不同饮食条件下的形态、基因表达和生长情况：Scaphiopus holbrookii（与大多数青蛙一样）从不产生肉食者；Spea multiplicata 有时会产生肉食者，但仅通过饮食诱导的可塑性；Spea bombifrons 无论饮食如何，通常都会产生肉食者。与 PFE 一致，我们发现 Sc. holbrookii 存在饮食诱导的可塑性——形态和基因表达——在 Sp. multiplicata 中适应性地细化了这种可塑性，并且在 Sp. bombifrons 中进一步细化了肉食者表型。总的来说，表型可塑性可能在进化创新中发挥重要作用（尽管未被充分认识）。
