Among anuran species with biphasic life cycle, the occurrence of intraspecific larval morphotypes has been related to variations in developmental time, diet, geographical variation, or response to predators. Here, we evaluated the external morphological variation of larvae among three populations, located more than 270 km apart, of the anuran hylid Scinax fuscovarius by linear and geometric methods, to elucidate the presence of geographically different morphs. Comparisons targeted development, growth, and external morphology. Studied populations exhibited differences in reproductive seasonality, growth rate, timing of development, shape, and size. Shape and size comparisons revealed two well-differentiated morphs, one of them shared by the two closest populations. Morphological differences evidenced a smaller and depressed form of the entire body plan in the most distant population, which showed continuous reproduction throughout the rainy season and under more unpredictable conditions. We interpret the occurrence of the two different larval morphs in S. fuscovarius as a by-product of local geographical conditions, and discuss on possible associations with biotic and abiotic factors cues.

中文翻译：

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Anuran 蝌蚪形状和大小的地理变异：Scinax fuscovarius（Anura，Hylidae）的种群间比较

在具有双相生命周期的无尾类物种中，种内幼虫形态型的发生与发育时间、饮食、地理变异或对捕食者的反应的变化有关。在这里，我们通过线性和几何方法评估了相距超过 270 公里的三个无尾蜥种群 Scinax fuscovarius 幼虫的外部形态变异，以阐明地理上不同形态的存在。比较针对发育、生长和外部形态。研究的种群在生殖季节性、生长速度、发育时间、形状和大小方面表现出差异。形状和大小比较揭示了两种分化良好的变体，其中一个由两个最接近的种群共享。形态差异证明了最远距离的种群整体体型更小、更压抑，在整个雨季和更不可预测的条件下都表现出连续繁殖。我们将 S. fuscovarius 中两种不同幼虫形态的出现解释为当地地理条件的副产品，并讨论与生物和非生物因素线索的可能关联。