| Summary: | Bees provide the essential ecosystem service of pollination, contributing ca. 35% of global food production, but declines in their populations have been reported worldwide. Currently, one third of the Irish bee fauna is listed as threatened. This thesis aimed to provide essential information on the conservation genetics and ecology of Irish bees. A comparis?n of published data on microsatellite markers revealed that haplodiploidy alone had no influence on genetic div~rsity whereas eusociality probably reduced it. Globally, >90% of bee species are solitary, rather than social. Ireland has over 75% of the Atlantic zone populations of Colletes floralis, an endangered solitary species. Using novel microsatellite markers,' C. floralis populations exhibited considerable genetic and geographic structuring, with little evidence of inbreeding. The taxonomy of Bombus sensu stricto is complicated by intraspecific variation. ' Phylogenetic analyses of CO1 sequences confirmed a barcoding gap between three cryptic species of the B. lucorum complex. A novel PCR-RFLP method differentiated and described the Irish distribution of them. Furthermore, an independent dataset of Irish bumblebee species tested alternative hypotheses regarding bumblebee declines. Despite parallel declines in Britain and Ireland, there was no relationship between declines and species' European ranges or food-plant specialisatiOIi.. The majority of Ireland's landmass is involved in agriculture, necessitating the accurate description of bee communities within the remaining areas .of conserved habitat. A survey of protected sites found that calcareous grasslands and dry heaths had the highest diversity 'and density of bees, respectively. Despite considerable niche overlap, communities were not highly competitively structured. Up to 72% of the variation in species-abundance distributions could be explained by characters relating to nesting habitat. Only upon integrating population genetics, intrinsic site characters and extrinsic, landscape scale, factors will habitat management translate into sustainable conservation management of Irish bees and the pollination services they provide.
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