Spatial patterns of habitat use in congeneric vipers across a Mediterranean ecotone

Congeneric species often exhibit intense competitive interactions due to their shared exploitation of resources. This study investigated habitat use patterns in two parapatric Iberian viper species, Vipera aspis and Vipera latastei. Habitats were described in terms of plant communities, and community turnover was evaluated using Moran’s correlograms, along with climatic and spatial factors that accounted for this turnover. Marked differences in habitat turnover rates were found between the two viper species. In V. aspis, the analysis indicated the use of more heterogeneous environments, with spatial clustering disappearing at intermediate distances (71.4 km). In V. latastei, the loss of spatial clustering occurred at considerably greater distances (246.4 km), and a core set of plant species persisted across habitats, even over long distances (up to 500 km). Climate was an important factor shaping habitat turnover, explaining 19.3% of the variability in V. aspis and 21.2% in V. latastei. Spatial factors were more influential for V. latastei (24.5%) than for V. aspis (9.8%). Our results also indicated that V. aspis and V. latastei occupy ecologically complementary areas, yet exhibit overlap within a sub-Mediterranean ecotone. Both species prefer habitats with high plant richness, suggesting an affinity for undisturbed environments offering greater prey density.