Spatial patterns of immunogenetic and neutral variation underscore the conservation value of small, isolated American badger populations

Small and isolated populations often exhibit low genetic diversity due to drift and inbreeding, but may simultaneously harbour adaptive variation. We investigate spatial distributions of immunogenetic variation in American badger subspecies (Taxidea taxus), as a proxy for evaluating their evolutionary potential across the northern extent of the species' range. We compared genetic structure of 20 microsatellites and the major histocompatibility complex (MHC DRB exon 2) to evaluate whether small, isolated populations show low adaptive polymorphism relative to large and well-connected populations. Our results suggest that gene flow plays a prominent role in shaping MHC polymorphism across large spatial scales, while the interplay between gene flow and selection was stronger towards the northern peripheries. The similarity of MHC alleles within subspecies relative to their neutral genetic differentiation suggests that adaptive divergence among subspecies can be maintained despite ongoing gene flow along subspecies boundaries. Neutral genetic diversity was low in small relative to large populations, but MHC diversity within individuals was high in small populations. Despite reduced neutral genetic variation, small and isolated populations harbour functional variation that likely contribute to the species evolutionary potential at the northern range. Our findings suggest that conservation approaches should focus on managing adaptive variation across the species range rather than protecting subspecies per se.

Determination of areas with the most significant shift in persistence of pests in Europe under climate change

BACKGROUND

This study aimed to estimate the impact of climate change on the ranges of crop pest species in Europe. The organisms included in the study were species from the family Tortricidae (Cydia pomonella, Lobesia botrana) and the family Pyralidae (Ostrinia nubilalis), Chrysomelidae beetles (Leptinotarsa decemlineata, Oulema melanopus) and species from the family Aphididae (Ropalosiphum padi, Sitobion avenae). Climate conditions in the year 2055 were simulated using a subset of five representative global circulation models. Model simulations using these climate change scenarios showed significant shifts in the climatic niches of the species in this study.

RESULTS

For Central Europe, the models predicted a shift in the ranges of pest species to higher altitudes and increases in the number of generations (NG) of the pests. In contrast, in the southern regions of Europe, the NG is likely to decrease owing to insufficient humidity. The ranges of species are likely to shift to the north.

CONCLUSION

Based on the ensemble-scenario mean for 2055, a climate-driven northward shift of between 3° N (O. nubilalis) and 11° N (L. botrana) is expected. The areas that are most sensitive to experiencing a significant increase in climate suitability for future pest persistence were identified. These areas include Central Europe, the higher altitudes of the Alps and Carpathians and areas above 55° N.