Data from: Effect of captivity on morphology: negligible changes in external morphology mask significant changes in internal morphology

Captive breeding programmes are increasingly relied upon for threatened species management. Changes in morphology can occur in captivity, often with unknown consequences for reintroductions. Few studies have examined the morphological changes that occur in captive animals compared with wild animals. Further, the effect of multiple generations being maintained in captivity, and the potential effects of captivity on sexual dimorphism remain poorly understood. We compared external and internal morphology of captive and wild animals using house mouse (Mus musculus) as a model species. In addition, we looked at morphology across two captive generations, and compared morphology between sexes. We found no statistically significant differences in external morphology, but after one generation in captivity there was evidence for a shift in the internal morphology of captive-reared mice, captive-reared mice (two generations bred) had lighter combined kidney and spleen masses compared with wild-caught mice. Sexual dimorphism was maintained in captivity. Our findings demonstrate that captive breeding can alter internal morphology. Given that these morphological changes may impact organismal functioning and viability following release, further investigation is warranted. If the morphological change is shown to be maladaptive, these changes would have significant implications for captive-source populations that are used for reintroduction including reduced survivorship.濒危物种管理正日益依赖圈养繁育计划。圈养环境下可能发生形态学改变，此类改变对物种再引入的影响通常尚不明确。目前鲜有研究对比圈养动物与野生动物的形态学差异。此外，圈养多代繁育的影响，以及圈养环境对性二态性（sexual dimorphism）的潜在效应，目前仍知之甚少。本研究以小家鼠（Mus musculus）为模式物种，对比了圈养与野生个体的外部及内部形态学特征。此外，本研究还分析了两代圈养个体的形态学特征，并对比了不同性别的形态差异。研究未发现两组个体在外部形态学特征上存在统计学显著差异，但经一代圈养繁育后，圈养小鼠的内部形态学特征已出现偏移；繁育两代的圈养小鼠，其肾脏与脾脏的总重量显著低于野生捕获个体。圈养环境下仍维持了性二态性。本研究结果表明，圈养繁育可改变动物的内部形态学特征。鉴于此类形态学改变可能影响个体释放后的机体功能与生存能力，因此有必要开展进一步研究。若此类形态学改变被证实为适应不良，则会对用于物种再引入的圈养源种群产生重大负面影响，包括降低其野外存活能力。