1. Paedomorphosis, a developmental heterochrony involving the retention of larval traits at the adult stage, is considered a major evolutionary process because it can generate phenotypic variation without requiring genetic modifications. Two main processes underlie paedomorphosis: neoteny, a slowdown of somatic development, and progenesis, a precocious maturation associated to body size reduction. Being essentially a truncation of ontogeny, progenesis has often been deemed an evolutionary dead-end with advantages attributed to precocious reproduction or small body size required in specific environmental contexts (e.g. parasitism, interstitial life), but there is a lack of studies on the immediate ecological consequences of progenesis. 2. Because body size is a key factor determining trophic ecology in animals, we hypothesized that progenesis might intrinsically promote ecological opportunity via body size reduction (i.e. ‘the trophic advantage of progenesis’ hypothesis). We tested this hypothesis in facultatively progenetic palmate newts (Lissotriton helveticus) using stable isotope niche modelling and diet reconstruction in conjunction with traditional stomach content analyses and body condition assessment. 3. We show that not only did progenetic individuals occupy a different trophic niche than metamorphic individuals in all populations, but the smaller they were compared to metamorphs due to progenesis, the more different they were in terms of trophic ecology, with no negative effect on their body condition. 4. Altogether, the results suggest that via body size reduction, progenesis may generally act as an intrinsic factor of ecological opportunity, allowing the use of existing but previously unavailable resources, even in habitats where seemingly little opportunity exists. We argue that beyond the classically recognized fitness advantages of progenetic development, this process may also generally bring an immediate trophic advantage via body size reduction, which would have important implications to understand the evolution and adaptiveness of this process in many different taxa, from marine meiofauna to primates.

中文翻译：

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生殖作为多表型两栖动物生态机会的内在因素

1. Paedomorphosis，一种发育异时性，涉及在成虫阶段保留幼虫性状，被认为是一个主要的进化过程，因为它可以在不需要遗传修饰的情况下产生表型变异。两个主要过程是幼体发育的基础：幼稚，体细胞发育减慢，以及生殖，与体型减小相关的早熟。由于本质上是个体发育的截断，后代通常被认为是进化的死胡同，其优势归因于在特定环境背景下（例如寄生性、间质性生活）所需的早熟繁殖或小体型，但缺乏对直接作用的研究生殖的生态后果。2. 因为体型是决定动物营养生态的关键因素，我们假设后代可能通过减少体型（即“后代的营养优势”假设）本质上促进生态机会。我们使用稳定同位素生态位建模和饮食重建结合传统的胃内容物分析和身体状况评估在兼性后代掌状蝾螈（Lissotriton helveticus）中测试了这一假设。3. 我们表明，不仅在所有种群中，后代个体与变态个体占据不同的营养生态位，而且由于后代与变态个体相比，它们在营养生态方面的差异越大，对它们没有负面影响。他们的身体状况。4. 总而言之，结果表明，通过体型减小，后代通常可以作为生态机会的内在因素，允许使用现有但以前不可用的资源，即使在看似几乎没有机会的栖息地。我们认为，除了经典公认的后代发育的适应性优势之外，这一过程通常还可能通过体型减小带来直接的营养优势，这对于了解该过程在来自海洋小型动物的许多不同分类群中的进化和适应性具有重要意义。灵长类动物。