Genetic structure and distinctness of Apis mellifera L. populations from the Canary Islands

Abstract

The genetic structure of Apis mellifera populations from the Canary Islands has been assessed by mitochondrial (restriction fragment length polymorphisms of the intergenic transfer RNAleu-COII region) and nuclear (microsatellites) studies. These populations show a low level of genetic variation in terms of average number of alleles and degree of heterozygosity. Significant differences in the distribution of alleles were found in both data sets, confirming the genetic differentiation among some of the islands but not within them. Two mitochondrial haplotypes characteristic of the Canary Islands are found at high frequencies, although populations are introgressed by imported honeybees of eastern European C lineage. This introgression is rather high on Tenerife and El Hierro and low on Gran Canaria and La Gomera, whereas on La Palma it has not been recorded. The finding of microsatellite alleles characteristic of the eastern European lineage corroborates the genetic introgression. Phylogenetic analyses indicate that the Canarian honeybees are differentiated from other lineages and provide genetic evidence of their African origin.

Developing reduced SNP assays from whole‐genome sequence data to estimate introgression in an organism with complex genetic patterns, the Iberian honeybee (Apis mellifera iberiensis)

“…Unlike many populations of A. m. mellifera from western Europe and A. m. iberiensis from the archipelagos of Baleares and Macaronesia , which are threatened by human‐mediated gene flow (De la Rúa et al., 2001, 2003; Jensen et al., 2005; Miguel et al., 2015; Muñoz et al., 2014; Pinto et al., 2014), there is very limited introgression in A. m. iberiensis populations of Iberia (Chávez‐Galarza et al., 2015). Therefore, it is crucial to monitor Iberian populations, before gene complexes shaped by natural selection over evolutionary time are irretrievably lost.…”

“…This important Iberian reservoir of genetic diversity has not yet been seriously threatened by C‐lineage introgression (Chávez‐Galarza et al., 2015, 2017; Miguel, Iriondo, Garnery, Sheppard, & Estonba, 2007), although this scenario might change as many young beekeepers are attracted by the advertised benefits of commercial strains—being more prolific and docile. In many islands of the Baleares and Macaronesia, for example where the Iberian honeybee was presumably introduced in historical times, the contemporaneous large‐scale importation of commercial C‐lineage queens has resulted in high levels of introgression into the local populations (De la Rúa, Galián, Serrano, & Moritz, 2001, 2003; Miguel et al., 2015; Muñoz, Pinto, & De la Rúa, 2014). The conservation of A. m. iberiensis diversity is therefore a priority, especially in the light of climate change as this subspecies is well adapted to a broad range of environments, including hot and dry summer months with limited nectar flows.…”

Effects of queen importation on the genetic diversity of Macaronesian island honey bee populations (Apis melliferaLinneaus 1758)

“…Earlier microsatellite studies found that the genetic diversity of Macaronesian honey bees is characterized by low values, as reflected by the number of alleles (nA) and heterozigosity (He) values (De la Rúa et al, 2001Rúa et al, , 2006. Despite significant temporal mitochondrial changes detected in the Macaronesian honey bee populations (Muñoz et al, 2013), our present study suggests that nuclear genetic diversity has not varied significantly and has remained relatively low.…”

“…As a result of isolation and adaptation to particular environmental island conditions, many organisms have given rise to locally adapted populations, such is the case of the honey bee, Apis mellifera Linneaus 1758. Indeed, honey bee populations locally adapted to endemic Macaronesian flora and particular weather and orography conditions are characterized by particular mitochondrial haplotypes (A11, A14, A15, and A16) belonging to the African evolutionary sub-lineage with Atlantic distribution (De la Rúa et al, 1998, 2001, 2006.…”

“…Such introduction events have been inferred through concurrent analyses of mitochondrial DNA (De la Rúa et al, 1998Rúa et al, , 2002 and microsatellite markers (De la Rúa et al, 2001, 2006. Furthermore, recent temporal analyses revealed differential patterns of change in mitochondrial diversity: whereas an increase of the introduction rate was observed on the Canary Islands such as El Hierro and La Gomera, diversity has remained stable in the other Macaronesian islands (Muñoz et al, 2013).…”