Data from: Intraspecific adaptive radiation: competition, ecological opportunity, and phenotypic diversification within species

Intraspecific variation in resource-use traits can have profound ecological and evolutionary implications. Among the most striking examples are resource polymorphisms, where alternative morphs that utilize different resources evolve within a population. An underappreciated aspect of their evolution is that the same conditions that favor resource polymorphism—competition and ecological opportunity—might foster additional rounds of diversification within already existing morphs. We examined these issues in spadefoot toad tadpoles that develop into either a generalist ‘omnivore’ or a specialist ‘carnivore’ morph. Specifically, we assessed the morphological diversity of tadpoles from natural ponds and experimentally induced carnivores reared on alternative diets. We also surveyed natural ponds to determine if the strength of intramorph competition and the diversity and abundance of dietary resources (measures of ecological opportunity) influenced the diversity of within-morph variation. We found that five omnivore and four carnivore types were present in natural ponds; alternative diets led to shape differences, some of which mirrored variation in the wild; and both competition and ecological opportunity were associated with enhanced morphological diversity in natural ponds. Such fine-scale intraspecific variation might represent an underappreciated form of biodiversity and might constitute a crucible of evolutionary innovation and diversification.

种内资源利用性状的变异可产生深远的生态与进化效应。其中最具代表性的实例为资源多态性（resource polymorphism）：即种群内演化出利用不同资源的替代形态。其演化过程中一个未被充分重视的维度在于，那些驱动资源多态性形成的核心条件——竞争与生态机会（ecological opportunity）——或可推动已存在的形态内部发生新一轮的多样化分化。我们以锄足蟾蝌蚪为研究对象，这类蝌蚪可发育为广食性“杂食者”与专食性“食肉者”两种特化形态。具体而言，我们评估了天然池塘中蝌蚪的形态多样性，以及通过不同日粮饲养实验诱导产生的食肉者形态的形态差异；同时，我们对天然池塘开展系统性调查，以明确形态内竞争强度、膳食资源的多样性与丰度（即生态机会的量化指标）是否会显著影响形态内部的变异多样性。研究结果显示，天然池塘中共存在5种杂食者类型与4种食肉者类型；不同日粮条件可诱导蝌蚪产生形态分化，其中部分差异与野外自然种群中的表型变异高度吻合；且竞争与生态机会均与天然池塘中蝌蚪的形态多样性提升呈显著正相关。这类精细尺度的种内变异或代表了一种未被充分认知的生物多样性形式，同时可能构成进化创新与多样化演化的核心熔炉。