The capacity of certain animals to regrow a lost appendage has been exploited as a powerful tool to study development. As a result, we now understand many of the proximate details of the regeneration process. Ironically, despite being one of the oldest studied developmental phenomena, regeneration is not often considered in the context of natural selection and evolution. Why do select species retain the capacity to shed and regrow body parts, whereas more derived lineages do not? We conducted a comprehensive study on the costs and benefits of autotomy and regeneration on Hemigrapsus nudus, the purple shore crab. In the realms of feeding and locomotion, regeneration restored fitness to what it otherwise would have been; autotomized animals showed decreases in feeding and locomotion, but regenerated animals performed no differently than intact crabs. However, for fecundity and male–male competition, regenerated animals had the lowest fitness compared with control and autotomized crabs. Our results raise the intriguing possibility that tradeoffs associated with reproduction may have led to the loss of regenerative abilities in derived lineages such as mammals and birds. Future work on the hundreds of species that regenerate lost body parts will reveal if and how this hypothesis can address the pervasive speculation plaguing the ultimate causes of regenerative losses.

中文翻译：

---

与自体切除和再生相关的权衡及其在再生能力进化中的潜在作用

某些动物重新长出失去的附属物的能力已被用作研究发育的有力工具。结果，我们现在了解了再生过程的许多近似细节。具有讽刺意味的是，尽管再生是研究最古老的发育现象之一，但在自然选择和进化的背景下并不经常考虑再生。为什么选择的物种保留了脱落和再生身体部位的能力，而更多衍生的血统却没有？我们对紫岸蟹 Hemigrapsus nudus 的自体切除和再生的成本和收益进行了全面研究。在进食和运动领域，再生恢复了原本应有的健康状态。自动切除的动物在进食和运动方面表现出下降，但再生动物的表现与完整的螃蟹没有什么不同。然而，对于繁殖力和雄性 - 雄性竞争，再生动物与对照和自动切除的螃蟹相比具有最低的适应度。我们的研究结果提出了一种有趣的可能性，即与繁殖相关的权衡可能导致哺乳动物和鸟类等衍生谱系丧失再生能力。未来对数百种再生丢失身体部位的物种的研究将揭示这一假设是否以及如何解决困扰再生损失最终原因的普遍猜测。