Whole-Genome Scan in Thelytokous-Laying Workers of the Cape Honeybee (Apis mellifera capensis): Central Fusion, Reduced Recombination Rates and Centromere Mapping Using Half-Tetrad Analysis

Abstract

While workers of almost all subspecies of honeybee are able to lay only haploid male eggs, Apis mellifera capensis workers are able to produce diploid female eggs by thelytokous parthenogenesis. Cytological analyses have shown that during parthenogenesis, egg diploidy is restored by fusion of the two central meiotic products. This peculiarity of the Cape bee preserves two products of a single meiosis in the daughters and can be used to map centromere positions using half-tetrad analysis. In this study, we use the thelytokous progenies of A. m. capensis workers and a sample of individuals from a naturally occurring A. m. capensis thelytokous clone to map centromere position for most of the linkage groups of the honeybee. We also show that the recombination rate is reduced by Ͼ10-fold during the meiosis of A. m. capensis workers. This reduction is restricted to thelytokous parthenogenesis of capensis workers and is not observed in the meiosis of queen within the same subspecies or in arrhenotokous workers of another subspecies. The reduced rate of recombination seems to be associated with negative crossover interference. These results are discussed in relation to evolution of thelytokous parthenogenesis and maintenance of heterozygosity and female sex after thelytoky.

Thelytokous parthenogenesis and its consequences on inbreeding in an ant

“…Automictic parthenogenesis with central fusion is also involved in the production of females by unmated workers in the cape honeybee Apis mellifera capensis (Verma and Ruttner, 1983). Interestingly, Baudry et al (2004) reported an average reduction of heterozygosity per generation and per individual (R) of about 0.19, a value well in the range of 0.06-0.33 (mean: 0.21) found in this study. By contrast with C. cursor, Schilder et al (1999) reported that reproduction in parthenogenetic populations of the ant Platythyrea punctata is apomictic.…”

“…Cytological analysis indicated that diploidization results from automictic parthenogenesis with central fusion, that is, the fusion of two of the four meiotic products that have a central position on the spindles and that were separated at the first meiotic division, whereas the two terminal nuclei degenerate (Verma and Ruttner, 1983;Baudry et al, 2004). In ants, thelytokous parthenogenesis has been unambiguously demonstrated in six phylogenetically distant species only: Cataglyphis cursor (Cagniant, 1973), Pristomyrmex pungens (Itow et al, 1984), Cerapachys biroi (Tsuji and Yamauchi, 1995), Platythyrea punctata (Heinze and Hö lldobler, 1995;Schilder et al, 1999), Messor capitatus (Grasso et al, 2000) and Wasmannia auropunctata (Fournier et al, 2005).…”

Factors affecting the dynamics of the honeybee (Apis mellifera) hybrid zone of South Africa

“…Microsatellite studies have shown that this infestation almost certainly arose from a single capensis worker that has multiplied automatically to produce a vast parasitizing population of workers of very similar genotype (Baudry et al, 2004). One is tempted to presume that this pseudo-clone has special characteristics that favour parasitism.…”

Effects of age and Reproductive Status on Tergal Gland Secretions in Queenless Honey bee Workers, Apis mellifera scutellata and A. m. capensis

“…Since the introduction of an A. m. capensis parasitic lineage (clones) (Baudry et al 2004) into the native range of A. m. scutellata in the northern region of South Africa (Allsopp and Crewe 1993;Johannsmeier 1997) (Du Toit 2001;Johannsmeier 2001). This has forced some commercial beekeepers out of business, resulting in an increase in the price of honey and other bee products as well as the cost of pollination services (Du Toit 2001;Johannsmeier 2001).…”