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段中，生物体体型呈现缩小趋势。全球变化对生物多样性造成显著影响，而体型缩小是生物对全球变暖的第三大常见响应。目前针对变温动物（ectotherms）的体型异速生长（body size allometry）仍有待进一步探究；本研究旨在通过以下五方面测试，深入解析调控鱼类体型的内在机制：i）结合温度与海拔验证贝格曼法则（Bergmann’s rule）；ii）探究其他潜在环境驱动因子；iii）解析隔离效应的作用；iv）对比本土与外来物种，验证生态进化假说；v）通过对比洄游性与定居性物种，明确迁徙倾向的影响。本研究针对智利鱼类构建了涵盖12科25种的大型数据集，共包含75198条记录，采样纬度范围为-28.80至-51.42；研究采用线性混合模型（linear mixed models），筛选出对体型变化影响最显著的环境变量，同时纳入扩散能力、生物地理隔离（biogeographic isolation）以及外来/本土物种互作强度等相关因子进行分析。研究结果证实海拔变化符合贝格曼法则，同时发现淡水鱼类体型随环境异质性与生态系统生产力的提升而增大。总体而言，内陆本土鱼类体型普遍小于沿海同类，部分物种呈现巨型化（gigantism）或矮化（dwarfism）特征，这为岛屿法则（island rule）提供了实证支持。若无扩散能力（洄游性与定居性鱼类的差异）或生物地理隔离相关机制等额外因子的干扰，本土与外来鱼类受体型调控的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、生态生产力、地理区位、迁徙能力以及物种起源均会对其体型产生影响。深入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针对性的生物多样性管理优先策略。