THE ORIGIN OF WEST EUROPEAN SUBSPECIES OF HONEYBEES (APIS MELLIFERA): NEW INSIGHTS FROM MICROSATELLITE AND MITOCHONDRIAL DATA

Abstract

Apis mellifera is composed of three evolutionary branches including mainly African (branch A), western and northern European (branch M), and southeastern European (branch C) populations. The existence of morphological clines extending from the equator to the Polar Circle through Morocco and Spain raised the hypothesis that the branch M originated in Africa. Mitochondrial DNA analysis revealed that branches A and M were characterized by highly diverged lineages implying very remote links between both branches. It also revealed that mtDNA haplotypes from lineages A coexisted with haplotypes M in the Iberian Peninsula and formed a south-north frequency cline, suggesting that this area could be a secondary contact zone between the two branches. By analyzing 11 populations sampled along a France-Spain/Portugal-Morocco-Guinea transect at 8 microsatellite loci and the DraI RFLP of the COI-COII mtDNA marker, we show that Iberian populations do not present any trace of "africanization" and are very similar to French populations when considering microsatellite markers. Therefore, the Iberian Peninsula is not a transition area. The higher haplotype A variability observed in Spanish and Portuguese samples compared to that found in Africa is explained by a higher mutation rate and multiple and recent introductions. Selection appears to be the best explanation to the morphological and allozymic clines and to the diffusion and maintenance of African haplotypes in Spain and Portugal.

Microsatellite variability reveals beekeeping influences on Iberian honeybee populations

“…Data from SNPs led to postulate the African origin of A. mellifera and that there were at least two subsequent expansions into Eurasia-a western expansion into Europe (M) and one or more eastern expansion into Asia and Europe (O and C; Whitfield et al 2006). The intermediate values of microsatellite heterozygosity agree with the survival of Iberian populations during the last glaciation event-which lately colonised Western Europe during present postglacial period-and the arrival of the hypothesised colonisation waves from North Africa (Garnery et al 1998b;Franck et al 1998;Miguel et al 2007; data presented here).…”

“…The number of alleles per locus and the heterozygosity values found in this study are higher than those reported by Franck et al (1998) for three samples from Sevilla, Segovia and San Sebastián (H e =0.283-0.331), and are more similar to those reported by De la for Murcia (SE Spain; H e =0.448) and by Miguel et al (2007) for different Iberian regions (H e =0.442-0.516). As a whole, the sampled populations are not structured according to a definite geographic pattern, in contrast to that found in mitochondrial haplotypes (Cánovas et al 2008).…”

“…Morphology, allozyme and mtDNA data clearly show a wide hybridisation area between African and European lineages where A. m. iberiensis occur (Ruttner 1988;Garnery et al 1998a;Franck et al 1998;Arias et al 2006;Miguel et al 2007;Cánovas et al 2008). Data from SNPs led to postulate the African origin of A. mellifera and that there were at least two subsequent expansions into Eurasia-a western expansion into Europe (M) and one or more eastern expansion into Asia and Europe (O and C; Whitfield et al 2006).…”

“…First results reported by Garnery et al (1998b) showed that microsatellite loci are much less variable in Iberia and France than in Africa, as a result of a hypothetical bottleneck in Iberian populations during the last glaciation (Franck et al 1998;Garnery et al 1998b). Microsatellites indicate a clear-cut disruption between Africa and Europe.…”

Genetic diversity of the endemic honeybee: Apis mellifera unicolor (Hymenoptera: Apidae) in Madagascar

“…Several clues and hypotheses point out the fact that A. m. unicolor might be derived from a recent (in geological time) colonization event of this continental island: i) relatively low mitochondrial and nuclear genetic diversity were found on A. m. unicolor in Madagascar, compared to other subspecies of the A lineage (Estoup et al 1995;Franck et al 1998Franck et al , 2001. ii) The hypothesis on molecular data showing A lineage split from other lineages 6 million years ago with A. m. unicolor divergence from other subspecies more recently (1 million years ago) (Han et al 2012).…”