Founder gene pool composition and genealogical structure in two populations of Austrian Carniolan honey bees (Apis mellifera carnica) as derived from pedigree analysis

Pedigree analyses describing gene pool and genetic diversity frequently have been performed for multiple livestock species. In honey bees, comparable studies are not yet available, and therefore, we aimed to investigate the genetic diversity of two Austrian Apis mellifera carnica breeding populations by means of pedigree analysis. Honey bee breeding programs in Austria get administered by two breeding associations, the ACA and the ZAC!. Their respective reference populations comprised the birth years 2019 and 2020 and resulted in 2.675 breeding queens within the ACA and 1.286 queens within the ZAC! population. From the total of 1.015 ACA founder queens, 13 founders represented 50% of the gene pool; for the ZAC! population (624 founders in total), 21 founders were responsible for 50% of the segregating alleles. The genetic diversity indices like effective numbers of founders (f(e)), ancestors (f(a)), and founder genome equivalents (n(g)) are capable to determine unbalanced breeding practices, occurrence of genetic bottlenecks, and genetic drift in the respective population histories. The values obtained (ACA/ZAC!: f(e) = 71/125; f(a) = 30/48; n(g) = 18.7/21.6) demonstrated genetic loss due to unbalanced, excessive use of single breeding animals within the ACA population. The slightly lower loss in diversity within the ZAC! population can be attributed to a smaller active population number. As a consequence, both populations exhibit moderate decrease of genetic diversity, which is comparable to mammal livestock with small or limited population size.

Automated summary

Pedigree analysis was employed to investigate the genetic diversity of two Austrian Apis mellifera carnica breeding populations. The results showed that a small number of founders contributed to a large proportion of the gene pool in both populations. The genetic diversity indices indicated a significant loss of diversity in the ACA population due to unbalanced breeding practices, while the ZAC! population exhibited a slightly lower loss in diversity attributed to a smaller active population size.