In this study, honey bees from the Macaronesian archipelago of the Azores were extensively surveyed to unveil diversity patterns. A total of 638 colonies were analyzed over two time periods using mtDNA and wing geometric morphometrics. The genetic composition revealed to be heterogeneous and related to historical and contemporary human-mediated introductions. The close relationship of Azorean populations with those from northern Portugal supports historical introductions by Portuguese settlers. The African sublineage A III prevailed on five islands, contrasting with three islands where C haplotypes were dominant. On Pico and Graciosa, C haplotypes are due to recent imports of commercial queens. On Faial, the sudden replacement of A III by C haplotypes coincided with arrival of Varroa destructor. This study deepens the current understanding of Macaronesian honey bees, suggesting that they are variants of the Iberian honey bee with differential levels of Cderived introgression. Iberian honey bee / tRNA leu-cox2 intergenic region / wing geometric morphometrics / DraI test
Our aim was to evaluate the occurrence of orchid bees in remnants of the Atlantic Forest. We sampled specimens from five regions of Southeast Brazil, covering three different physiognomies of the Atlantic Forest (mixed Araucaria forests with high altitude fields, Atlantic Semi-deciduous Forest and Atlantic Rain Forest). The distances between the sampling sites ranged from 24 to 746 km. Male orchid bees attracted by fragrances were actively sampled monthly during one year using entomological nets and aromatic traps. A total of 1,482 bees were captured, including four genera and at least 31 species. We observed differences in the abundance and richness of species sampled among sites. Climatic variables, mostly relative humidity, explained twice more of the observed differences in the Euglossini communities than simple spatial variation. Our study found differences in the composition of euglossine bee communities as well as in their patterns of abundance and dominance among different vegetation formations. However, the level of pairwise similarity among the Euglossini communities sampled, although highly variable, was not related to climatic factors or geographical distances between the sampling sites. The greatest dissimilarities in the composition of the orchid bee communities were observed between sites around 400 km from each other rather than among sites that were further apart. A possible explanation is that the sampled areas that were 400 km from each other were also highly dissimilar regarding climate, especially altitude.
The sampling of orchid bees across different biomes provides an excellent opportunity to analyze morphological variability in this group. We examined the morphological variation of populations of Eulaema nigrita in the context of the determination of geographic origin. It also evaluated population variability of this group in different landscapes from two important biomes, Atlantic Forest, Brazilian Savanna, and the transition zone between them. These analyses were achieved by documenting the pattern of morphological differentiation using geometric morphometric analysis of the wings of 256 individuals, sampled from nine locations, from four different physiognomies. Results indicated that individuals from the Atlantic Forest physiognomies are larger than the ones from the Savanna. The clusterization of individuals was based on landscape features of the sampling areas. The results indicate little or even a complete absence of population structure. Overall, site-specific population differentiation is not strongly supported by wing traits, reinforcing the statement consistent with the broader pattern that orchid bees have a high migratory capacity. However, the subtle differentiation may indicate the existence of locally adapted traits kept by female philopatry or phenotypic plasticity triggered by environmental factors yet to be studied.
In many organisms, habitat affects ecological and genetic diversity and, for certain species, it is expected that a large population should have higher genetic diversity than a smaller population. We analysed the genetics of males of the orchid bee, Eulaema nigrita (Hymenoptera: Apidae) and examined the links between local abundance and habitat with genetic diversity. We also investigated the impact of landscape features on genetic population structure, through microsatellite and mitochondrial DNA analysis, among populations found across 700 km of Brazilian Atlantic forest fragments. We found that genetic variation was not a function of local abundance, but it correlated significantly with habitat. There was significant but low genetic differentiation among populations. We found a single mitochondrial DNA haplotype in all sequenced specimens, which may be widespread throughout the Atlantic forest. Our results reinforce the idea that orchid bees can fly long distances. High-dispersal capacity, together with insufficient time in eventual isolation, can directly contribute to the high degree of similarity among populations for this species, despite their wide geographical distribution.
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