Genetic structure of the gentle Africanized honey bee population (gAHB) in Puerto Rico

Abstract

Background: The Africanized honey bee is one of the most spectacular invasions in the Americas. African bees escaped from apiaries in Brazil in 1956, spread over Americas and by 1994 they were reported in Puerto Rico. In contrast to other places, the oceanic island conditions in Puerto Rico may mean a single introduction and different dynamics of the resident European and new-coming Africanized bees.To examine the genetic variation of honey bee feral populations and colonies from different locations in Puerto Rico, we used eight known polymorphic microsatellite loci.

Results: In Puerto Rico, gAHB population does not show any genetic structure (Fst = 0.0783), and is best described as one honey bee population, product of hybridization of AHB and EHB. The genetic variability in this Africanized population was similar to that reported in studies from Texas. We observed that European private allele frequencies are high in all but one locus. This contrasts with mainland Africanized populations, where European allele frequencies are diminished. Two loci with European private alleles, one on Linkage Group 7, known to carry two known defensiveness Quantitative Trait Loci (QTLs), and the other on Linkage Group 1, known to carry three functionally studied genes and 11 candidate genes associated with Varroa resistance mechanisms were respectively, significantly greater or lower in European allele frequency than the other loci with European private alleles.

Conclusions: Genetic structure of Puerto Rico gAHB differs from mainland AHB populations, probably representing evolutionary processes on the island.

Figure 1

Map of Puerto Rico with apiaries sampled (triangle) and the research apiary (star).

Figure 2

Bar plot produced by STRUCTURE assuming 2 populations showed no separation. 1 and 2 indicate the samples from the island of Pueto Rico (1) and the satellite island, Vieques (2). And proportion of membership of each pre-defined population in 2 clusters.

Figure 3

Neighbor-joining tree, showing the genetic relationships among each individual member of sample locations in Puerto Rico, inferred from microsatellite data.

Figure 4

Comparison of the European allele frequency (E) among six microsatellite loci in a Hawaiian (Hawaii) and Puerto Rican (gAHB) bee population. The star (*) indicates the two loci where the difference was significant, A107 (X² = 6.60, df = 1, P < < 0.0001) and A79 (X² = 39.12, df = 1, P < 0.01).

Figure 5

Microsatellite loci A79, A113, A107, A14, A88, A35 and ED1 (black lines) associated to linkage groups with aggressive behavior Quantitative Trait Loci Sting 1, 2, and 3 (red line) [[51]] and Varroa resistance genes (blue lines): scracht (scrt), Dynein heavy chain 64C (Dhc64c), Immunoglobulin gene Superfamily (otk), groucho (gro), Futsch, paralytic (para), fringe (fng), Glutamate-gated Cl- channel (GluCl) [[52]] more three groups that including 11 new gene to Varroa Sensitive Hygiene Behavior [[57]].