Polymorphic STR markers as a tool for population-genetic studies of Apis mellifera honeybees (review)

The relevance of honey bee biology comprehensive study is increasing every year. Primarily, this is caused by the decline of honey bee populations which occurs all over the world including the Russian Federation. Historically, the Europe and Africa continents were the habitat of the only representative of genus Apis , the honey bee Apis mellifera from which a significant number of freely interbreeding races (subspecies) derived during evolution. Nowadays, due to human introduction of honey bees to other continents, Apis mellifera are found all around the world. The loss of unique gene pools and purebred status of native honey bee subspecies due to uncontrolled hybridization is a matter of great concern worldwide (P. de la Rúa et al., 2009). Therefore, evolutionary relationships and population genetics of A. mellifera , genetic control of domestic and imported breeding stock purity, breed authentication, genome-wide association mapping for traits of apicultural interest (e.g., queen performance, flight activity, honey and wax productivity, resistance to parasites, winter hardiness, royal jelly components, bee venom, etc.), and breeding value estimation are the key points of approach to biodiversity conservation in honey bees. The set of parameters characteristic of the population/line as a whole is the necessary base to preserve and maintain polymorphism as a component of population stability (N.I. Krivtsov et al., 2011). Genetic structure of breeding populations and relations between geographically isolated populations are relevant to characterize breed gene pool and optimize selection programs. The paper discusses general aspects of microsatellite structure, the main models of evolution (H. Fan et al., 2007) and putative mechanisms of origin in eukaryotic genomes (A.V. Omelchenko, 2013). Microsatellites are tandem repeats of short (2-6 bp) noncoding sequences that are dispersed throughout the nuclear genome (W.S. Sheppard et al., 2000). Microsatellites are located in both protein-coding and non-coding regions, including regulatory sequences (I. López-Flores et al., 2012). It is believed that microsatellites emerge and spread via formation of various non-canonical DNA structures that favor the slipping of replication forks (R.D. Wells, 1996). Microsatellite loci are a very convenient tool to analyze the genetic structure of populations, estimate genomic inbreeding and the level of heterozygosity, calculate genetic similarity coefficients, and determine the level of introgression. This paper overviews the use of STR markers for reconstruction of the honey bee evolutionary history. The principal research papers on population genetics of various A. mellifera subspecies from Europe, Asia, America, and Africa are comsidered. Special attention is paid to the Russian honey bee breeds and populations. To summarize, the STR markers due to the large number of alleles, the high frequency of mutational events and codominant type of inheritance continue to be extremely powerful tool for genomic mapping, verification of the genomic authenticity, and in genetic and evolutionary studies of populations.