A single locus determines thelytokous parthenogenesis of laying honeybee workers (Apis mellifera capensis)

Abstract

The evolution and maintenance of parthenogenetic species are a puzzling issue in evolutionary biology. Although the genetic mechanisms that act to restore diploidy are well studied, the underlying genes that cause the switch from sexual reproduction to parthenogenesis have not been analysed. There are several species that are polymorphic for sexual and parthenogenetic reproduction, which may have a genetic basis. We use the South African honeybee subspecies Apis mellifera capensis to analyse the genetic control of thelytoky (asexual production of female workers). Due to the caste system of honeybees, it is possible to establish classical backcrosses using sexually reproducing queens and drones of both arrhenotokous and thelytokous subspecies, and to score the frequency of parthenogenesis in the resulting workers. We found Mendelian segregation for thelytoky of egg-laying workers, which appears to be controlled by a single major gene (th). The segregation pattern indicates a recessive allele causing thelytoky. We found no evidence for maternal transmission of bacterial endosymbionts controlling parthenogenesis. Thelytokous parthenogenesis of honeybee workers appears to be a classical qualitative trait, because we did not observe mixed parthenogenesis (amphitoky), which might be expected in the case of multi-locus inheritance. Heredity (2005) 94, 533-537.

The genetics of obligate parthenogenesis in an aphid species and its consequences for the maintenance of alternative reproductive modes

“…Contagious asexuality has been reported in a wide range of arthropods (Delmotte et al, 2001;Lattorff et al, 2005;Paland et al, 2005;Halkett et al, 2008;Sandrock and Vorburger, 2011). When studied, inheritance of obligate asexuality has been found to be mono-or oligogenic in most cases.…”

“…In the rotifer Brachyonus calyciflorus, OP clones are homozygous for a recessive allele op, which renders them unable to respond to the chemical signals that usually induce sexual reproduction in this species (Scheuerl et al, 2011), whereas heterozygotes and homozygotes for the wild type are CP (Stelzer et al, 2010). In insects, all-female parthenogenesis (thelytoky) has been found to be inherited as a single-locus recessive trait in two hymenopterans, the Cape honeybee Apis mellifera capensis (Lattorff et al, 2005), and a solitary aphid endoparasitoid wasp, Lysiphlebus fabarum (Sandrock and Vorburger, 2011).…”

Thelytokous parthenogenesis and its consequences on inbreeding in an ant

“…In social Hymenoptera, it has been shown that thelytoky of Apis mellifera capensis workers is controlled by a single locus (Lattorff et al, 2005). 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).…”

Clinal nature of the frequencies of ovarioles and spermathecae in Cape worker honeybees,Apis mellifera capensis

“…The mandibular gland pheromones and ovariole development covary in queenless Cape workers (Hepburn, 1992) (both probably under separate genetic control), but thelytoky itself is a Mendelian trait (Lattorff et al, 2005). Jordan et al (2008) measured spermatheca size and number of ovarioles in the parental, hybrid and backcross offspring between thelytokous Cape bees and the highland bee A. m. scutellata and observed that they were phenotypically correlated but apparently under independent genetic control.…”