Effects of life history strategies and habitats on limb regeneration in plethodontid salamanders

Background: Salamanders are the only tetrapods that exhibit the ability to fully regenerate limbs. The axolotl, a neotenic salamander, has become the model organism for regeneration research. Great advances have been made providing a detailed understanding of the morphological and molecular pro- cesses involved in limb regeneration. However, it remains largely unknown how limb regeneration varies across salamanders and how factors like variable life histories, ecologies, and limb functions have influenced and shaped regen- erative capacities throughout evolution. Results: This study focuses on six species of plethodontid salamanders repre- senting distinct life histories and habitats. Specimens were examined for regen- eration ability after bite injuries as well as after controlled amputations. Morphological investigations revealed great regenerative abilities in all investi- gated species and frequent anatomical limb anomalies. Correlations were observed with respect to speed of regeneration and habitat. Conclusions: Investigating regeneration in non-model salamander taxa is essential for disentangling shared features of the regeneration process versus those that may be more taxon-specific. Gaining insights into variable aspects of regeneration under natural conditions and after conspecific biting rather than controlled amputations adds important new datapoints for understanding the evolutionary framework of regeneration and provides a broader context for interpreting findings made in the model organism axolotl.