Differential habitat associations in peripheral populations of threatened species: The case of the Caucasian grouse

Abstract

Treating a species as an evolutionally homogenous entity over its entire range and ignoring the effect of local adaptations and the consequences of species functional response to environmental gradients can lead to misguided conservation measures. The spatially distinct Caucasian grouse (CG) (Lyrurus mlokosiewiczi) populations across discontinuous range in the Caucasus Mountains would likely possess different adaptation traits which are of importance for conservation management. Using a separate distribution model for each of four different regions with the MaxEnt technique, we investigated if CG's functional responses to habitat features differ between the core and peripheral populations and thus, the occurrence‐habitat relationships could be better explained by region‐specific models than a single, range‐wide model. We validated the models using each region as a geographically independent dataset. The results revealed that although there was a similar response to elevation in the four regions and the species occurrence probability was highest at altitude about 2,500 m, there was a consistently higher mean annual temperature in the species' southeastern Lesser Caucasus range compared to the western and eastern parts of the Greater Caucasus region (p < 0.001). The southeastern population of CG was living under separate and unique climate conditions and did not share the same affinity to climate conditions as CG elsewhere; this may lead the species to be adapted this special climate condition through phenotypic plasticity or local adaptation. Long‐term evolutionary studies are essential to confirm CG intra‐specific variations, but in lack of knowledge of local adaptation, our recommendation is to treat CG as geographically distinct populations that may each require specific management.