Sex-specific shifts in morphology and diet in a frog after 50 years of anthropogenic habitat fragmentation

Aim: Phenotypic shifts are commonly observed when animals face insular habitat change and may reflect ongoing stresses on individuals. However, the generality and the driving processes of this ‘island rule’ remain equivocal, notably in amphibians. Here, we investigate both morphological and dietary shifts in a frog using a mosaic of human-created islands to assess the potential operating mechanisms underlying these phenotypic responses. Location: Thousand Island Lake, China. Taxon: The Chinese piebald odorous frog, Odorrana schmackeri. Results: We found insular dwarfism in female but not male frogs. Meanwhile, insular females also had smaller gape widths after accounting for snout-vent lengths (SVLs) than mainland females. According to SEMs, resource availability had a direct positive effect on body size. Finally, diet composition differed between island and mainland populations, but only in females. Males and females on islands exhibited greater overlaps in diet. Main conclusions: In c...研究目的：当动物面临岛屿生境改变时，通常会观测到表型偏移（phenotypic shifts），此类偏移或可反映个体正承受的持续压力。然而，这一“岛屿法则（island rule）”的普适性及其驱动过程尚存争议，尤以两栖动物类群为甚。本研究以人工构建的群岛镶嵌生境为研究系统，针对一种蛙类的形态与食性转变展开探究，以解析此类表型响应背后的潜在作用机制。 研究地点：中国千岛湖（Thousand Island Lake）。 研究类群：中国花臭蛙（Chinese piebald odorous frog, Odorrana schmackeri）。 研究结果：我们仅在雌性蛙类中发现了岛屿矮化（insular dwarfism）现象。同时，在矫正肛吻长（snout-vent lengths, SVLs）后，岛屿种群雌性的口裂宽度亦小于大陆种群雌性。基于结构方程模型（Structural Equation Models, SEMs），资源可获得性对体型具有直接正向影响。最后，岛屿与大陆种群的食性组成存在差异，但该差异仅见于雌性个体。岛屿种群的雌雄个体间食性重叠度更高。 主要结论：在c……