Data from: MHC structuring and divergent allele advantage in a urodele amphibian: a hierarchical multi-scale approach

The proteins encoded by extraordinarily polymorphic major histocompatibility complex (MHC) genes are involved in the adaptive immune response. Balancing selection is believed to maintain MHC polymorphism in the long-term, although neutral processes also play a role in shaping MHC diversity. However, the relative contribution of these processes is poorly understood. Here we characterized MHC class II variation of a low-dispersal, pond-breeding newt (Triturus carnifex) over a restricted, geographically structured area. We aimed to: (1) evaluate the contribution of selection and neutral processes to shaping MHC diversity at two geographic scales; and (2) test for signatures of divergent allele advantage (DAA), a potentially important mechanism of balancing selection. The dominant role of selection in shaping MHC variation was suggested by the lack of correlation between MHC and neutral (microsatellite) variation. Although most variation occurred within populations for both types of markers, they differed in the extent of structuring at the two spatial scales. MHC structuring was more pronounced at local scales, suggesting the role of local selection, while structuring was not detectable at a larger scale, possibly an effect of balancing selection. Microsatellites showed the opposite pattern. As expected under DAA, the observed genotypes combined more sequence diversity than expected under random association of alleles. Thus, DAA may contribute to maintaining MHC polymorphism, which is ancient, as supported by signatures of historical positive selection and trans-species polymorphism. Our results point to the importance of a multi-scale approach in studying MHC variation, especially in low-dispersal taxa, genetically structured at fine spatial scales

Males are faster foragers than females: Intersexual differences of foraging behaviour in the Apennine chamois

Availability of food resources and individual characteristics can influence foraging behaviour, which can differ between males and females, leading to different patterns of food/habitat selection. In dimorphic species, females are usually more selective in food choice, show greater bite rates and spend more time foraging than males. We evaluated sexual differences in foraging behaviour in Apennine chamois Rupicapra pyrenaica ornata, during the warm season, before the rut. Both sexes selected nutritious vegetation patches and spent a comparable amount of time feeding. However, males had a significantly greater feeding intensity (bite rate) and a lower search effort for feeding (step rate), as well as they spent more time lying down than females. Females selected foraging sites closer to refuge areas than males. In chamois, sexual size dimorphism is seasonal, being negligible in winter– spring, but increasing to 30–40 % in autumn. Our results suggest that males enhance their energy and mass gain by increasing their food intake rate during the warm season, to face the costs of the mating season (November). Conversely, females seem to prioritize a fine-scale selection of vegetation and the protection of offspring. A great food intake rate of males in the warm season could have developed as a behavioural adaptation leading herbivores to the evolutionary transition from year-round monomorphism to permanent dimorphism, through seasonal dimorphism

Competition between wild herbivores: Reintroduced red deer and Apennine chamois

Coevolved species should avoid competition through resource partitioning, but human-induced alteration of plant/animal communities may facilitate the onset of competitive interactions. In herbivores, access to high-quality forage in the warm months, that is, during nursing and weaning, influences growth and survival of offspring. In turn, resource exploitation by a reintroduced, superior competitor should affect offspring survival of the inferior one, by decreasing foraging efficiency and diet quality of mothers and young. We assessed the negative effects of reintroduced red deer Cervus elaphus on grassland, on foraging behavior of female Apennine chamois Rupicapra pyrenaica ornata (July–October 2012–2013) and on winter survival of chamois kids, across 3 study sites with different deer densities (great/intermediate/extremely low). The size of bare soil patches was positively associated with deer density and, in areas with deer, it increased throughout July–October. The volume of nutritious plants (i.e., legumes) in the diet of female chamois was lower and decreased faster between summer and autumn, in areas with deer than in that with an extremely low deer density. Feeding intensity (bite rate) of female chamois was significantly lower and their food searching (step rate) was greater in areas with deer. Chamois kids showed a significantly greater winter mortality, with a lower proportion of younger individuals, in areas with deer than in that with an extremely low deer density. In human-altered ecosystems, unpredictable consequences can follow interspecific interactions within restored animal communities. In turn, patterns of ecological relationships among ecosystem components may be modified, with an increase of the potential for competitive interactions