Data from: Chilean fish body size is influenced by multiple drivers

There is evidence that organisms have become smaller during the past periods of global warming. Global change has substantial effects on biodiversity, with body size reduction being the third most common response to global warming. Body size allometry in ectotherms needs to be explored further; the objectives of this study were to better understand the mechanisms regulating body size in fish by testing: i) Bergmann's rule with temperature and elevation, ii) additional environmental drivers, iii) the role of isolation, iv) ecoevolutionary hypotheses comparing native and exotic species, and v) the role of migration propensity in comparing migratory and resident species. We analyzed an extensive dataset of Chilean fish composed of 75,198 records which included 25 species from 12 different families between latitudes -28.80 to -51.42 using linear mixed models to discern the best environmental variables contributing to body size changes, as well as incorporating factors related to dispersal capabilities, biogeographic isolation, and levels of exotic/native interactions. Bergmann's rule is supported by changes in elevation, and our study shows that freshwater fish body size also increases with increasing environmental heterogeneity and productivity. In general, inland native fish tend to be smaller than coastal ones, supporting the island rule with evidence of gigantism or dwarfism in selected species. Ecological variables affecting fish body size do not differ between native and exotic fish unless other factors are considered, such as dispersal capacity (migrating vs. resident fish) or mechanisms related to their isolation. Although temperature is not a direct driver of body size in Chilean fish, heterogeneity, productivity, geography, migratory ability, and species origin may affect body size. A better understanding of the mechanisms driving body size in ectotherms will aid in determining management priorities in the face of global climate disruption.

已有研究表明，在过往的全球变暖时期中，生物体体型呈现缩小趋势。全球变化对生物多样性具有显著影响，而体型缩小是全球变暖下生物第三大常见的响应模式。变温动物（ectotherm）的体型异速生长规律仍有待进一步探究；本研究旨在通过以下测试更好地解析调控鱼类体型的机制：① 结合温度与海拔验证伯格曼法则（Bergmann's rule），② 探究其他潜在环境驱动因子，③ 解析隔离效应的作用，④ 通过对比本土与外来物种验证生态进化假说，⑤ 通过对比洄游与定居型物种探究迁徙倾向的影响。本研究构建了涵盖75198条记录的智利鱼类大规模数据集，该数据集包含来自12个科的25个物种，采样纬度范围为-28.80至-51.42；研究采用线性混合模型，以辨识对体型变化影响最为显著的环境变量，同时纳入了与扩散能力、生物地理隔离以及本土-外来物种互作水平相关的因子。海拔变化验证了伯格曼法则，同时本研究发现淡水鱼类体型随环境异质性与生产力提升而增大。总体而言，内陆本土鱼类体型通常小于沿海同类，这一结果支持岛屿法则（island rule），且部分物种存在体型巨型化或矮化的相关证据。除非纳入扩散能力（洄游型与定居型鱼类）或生物地理隔离相关机制等其他因子，否则本土与外来鱼类所受的体型调控生态变量并无显著差异。尽管温度并非智利鱼类体型变化的直接驱动因子，但环境异质性、生产力、地理区位、迁徙能力以及物种起源均可对其体型产生影响。更深入地解析变温动物体型调控机制，将有助于在全球气候扰动背景下制定鱼类资源管理的优先策略。