title: Meiotic recombination dramatically decreased in thelytokous queens of the little fire ant and their sexually produced workers.
abstract: The little fire ant, Wasmannia auropunctata, displays a peculiar breeding system polymorphism. Classical haplo-diploid sexual reproduction between reproductive individuals occurs in some populations, whereas, in others, queens and males reproduce clonally. Workers are produced sexually and are sterile in both clonal and sexual populations. The evolutionary fate of the clonal lineages depends strongly on the underlying mechanisms allowing reproductive individuals to transmit their genomes to subsequent generations. We used several queen-offspring data sets to estimate the rate of transition from heterozygosity to homozygosity associated with recombination events at 33 microsatellite loci in thelytokous parthenogenetic queen lineages and compared these rates with theoretical expectations under various parthenogenesis mechanisms. We then used sexually produced worker families to define linkage groups for these 33 loci and to compare meiotic recombination rates in sexual and parthenogenetic queens. Our results demonstrate that queens from clonal populations reproduce by automictic parthenogenesis with central fusion. These same parthenogenetic queens produce normally segregating meiotic oocytes for workers, which display much lower rates of recombination (by a factor of 45) than workers produced by sexual queens. These low recombination rates also concern the parthenogenetic production of queen offspring, as indicated by the very low rates of transition from heterozygosity to homozygosity observed (from 0% to 2.8%). We suggest that the combination of automixis with central fusion and a major decrease in recombination rates allows clonal queens to benefit from thelytoky while avoiding the potential inbreeding depression resulting from the loss of heterozygosity during automixis. In sterile workers, the strong decrease of recombination rates may also facilitate the conservation over time of some coadapted allelic interactions within chromosomes that might confer an adaptive advantage in habitats disturbed by human activity, where clonal populations of W. auropunctata are mostly found.
authors: INRA, UMR Centre de Biologie pour la Gestion des Populations (INRA/IRD/CIRAD/Montpellier SupAgro), Montferrier-sur-Lez cedex, France. olivier.rey@supagro.inra.fr
authors: Olivier
authors: O
authors: Rey
authors: Anne
authors: A
authors: Loiseau
authors: Benoit
authors: B
authors: Facon
authors: Julien
authors: J
authors: Foucaud
authors: Jérôme
authors: J
authors: Orivel
authors: Jean-Marie
authors: JM
authors: Cornuet
authors: Stéphanie
authors: S
authors: Robert
authors: Gauthier
authors: G
authors: Dobigny
authors: Jacques Hubert Charles
authors: JH
authors: Delabie
authors: Cléa Dos Santos Ferreria
authors: Cdos S
authors: Mariano
authors: Arnaud
authors: A
authors: Estoup
mesh_terms: D000483:Alleles; D000818:Animals; D001000:Ants / Q000235:genetics* / Q000502:physiology; D005075:Biological Evolution; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D007178:Inbreeding; D008540:Meiosis / Q000235:genetics; D010312:Parthenogenesis / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics*; D012098:Reproduction / Q000235:genetics*; D012919:Social Behavior