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.

濒危物种保护管理愈发依赖圈养繁育计划。圈养环境下可能发生形态学改变，其对物种再引入的影响往往尚不明确。目前鲜有研究对比分析圈养动物与野生动物的形态学差异。此外，圈养多代繁育对动物形态的影响，以及圈养环境对性二态性的潜在作用，目前仍未得到充分阐释。本研究以家鼠（Mus musculus）为模式物种，对比分析了圈养与野生个体的外部及内部形态特征。此外，本研究还考察了两代圈养个体的形态特征，并对比了不同性别间的形态差异。研究结果显示，两组个体的外部形态未出现统计学意义上的显著差异；但经过一代圈养后，人工繁育小鼠的内部形态已出现变化：繁育两代的圈养小鼠，其肾脏与脾脏总重量显著低于野生捕获个体。圈养环境下动物的性二态性得以保留。本研究结果证实，圈养繁育可改变动物内部形态。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，后续相关研究仍有待开展。若此类形态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显著负面影响，包括降低其野外存活能力。