Hybridisation and introgression can have negative impacts on regional biodiversity through the potential erosion of locally adapted lineages. The honey bee (Apis mellifera L.) occurs in twenty-seven subspecies across Europe, is an extremely economically important insect, yet threatened by multifarious impacts. Transhumance of the most commercially appealing varieties threatens native honey bee diversity by introgression and subsequent loss of locally adapted traits, or even by complete removal of some subspecies from parts of the range. Here levels of admixture and introgression are examined in UK honey bees suspected to be from hives of the dark European honey bee (Apis mellifera mellifera). Microsatellite DNA and STRUCTURE analyses reveal that the studied populations are generally admixed, and discriminant analysis of principal components shows them to be intermediate between A. m. mellifera and A. m. carnica populations. However, examining mitochondrial haplotype data (COI-COII intergenic spacer region) and nuclear DNA reveal that some hives are relatively pure (from four to fifteen hives, depending on the Q-value threshold). Genetic diversity is relatively high in comparison with other European populations. Implications for conservation and management are discussed.
1. Within the theoretical framework of the small population paradigm, we investigated the population genomics and parasite load of two bumblebee species across the UK and Ireland. Bombus pratorum is widespread and common throughout its range while Bombus monticola is restricted to higher altitudes and shows a more fragmented distribution.2. Bombus monticola showed stronger population structuring, isolation-by-distance, and a deficit of heterozygotes in the most isolated population in the south of its range (Dartmoor). Heterozygosity and inbreeding coefficients (F IS ) were comparable between both species, but the proportion of polymorphic sites was much greater in B. pratorum. Notably, both species have suffered significant declines in Ne over the last 100 generations and estimates and declines for both species were of similar orders of magnitude. No pattern of increased parasite prevalence in populations of lower heterozygosity was observed. Instead, ecological and demographic factors (age, latitude, date, habitat suitability) were the main drivers of parasite prevalence.3. Distinct patterns of selection were observed in both species in regions involved in regulation of transcription and neurotransmission and in particular pathways targeted by neonicotinoid insecticides. 4. Our results highlight the pressing need for monitoring to include common as well as rare species. This should not focus solely on census population counts, but include estimates of Ne. We also highlight the need for further work to establish adaptive shifts in globally important pollinator communities.
Aim We compare the performance of habitat suitability models using climate data only or climate data together with water chemistry, land cover and predation pressure data to model the distribution of European grayling (Thymallus thymallus). From these models, we (a) investigate the relationship between habitat suitability and genetic diversity; (b) project the distribution of grayling under future climate change; and (c) model the effects of habitat mitigation on future distributions. Location United Kingdom. Methods Maxent species distribution modelling was implemented using a Simple model (only climate parameters) or a Full model (climate, water chemistry, land use and predation pressure parameters). Areas of high and low habitat suitability were designated. Associations between habitat suitability and genetic diversity for both neutral and adaptive markers were examined. Distribution under minimal and maximal future climate change scenarios was modelled for 2050, incorporating projections of future flow scenarios obtained from the Centre for Ecology and Hydrology. To examine potential mitigation effects within habitats, models were run with manipulation of orthophosphate, nitrite and copper concentrations. Results We mapped suitable habitat for grayling in the present and the future. The Full model achieved substantially higher discriminative power than the Simple model. For low suitability habitat, higher levels of inbreeding were observed for adaptive, but not neutral, loci. Future projections predict a significant contraction of highly suitable areas. Under habitat mitigation, modelling suggests that recovery of suitable habitat of up to 10% is possible. Main conclusions Extending the climate‐only model improves estimates of habitat suitability. Significantly higher inbreeding coefficients were found at immune genes, but not neutral markers in low suitability habitat, indicating a possible impact of environmental stress on evolutionary potential. The potential for habitat mitigation to alleviate distributional changes under future climate change is demonstrated, and specific recommendations are made for habitat recovery on a regional basis.
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