Absence of variation in body size of the alpine salamander between allotopic and syntopic populations in a contact zone with the fire salamander

Competition can lead to differences in body size between syntopic and allotopic conspecific populations. Salamandra atra and S. salamandra are parapatric but have narrow contact zones where the two species are likely to compete. To test for divergence in functional traits in S. atra, we compared its body size and mass between locations where the species is syntopic or allotopic with S. salamandra. Using mixed-effect models, we found no significant differences in body size or mass between syntopic and allotopic locations. This suggests either that the two species do not compete or that competition does not lead to divergence in body size in S. atra