Résumé
Androgenesis is the production of an offspring containing exclusively the
nuclear genome of the fathering male, via the maternal eggs. This unusual
mating system is generally considered as a male trait, giving to
androgenetic males a substantial fitness advantage over their sexually
reproducing relatives. We here provide the first empirical study of the
evolutionary outcomes of androgenesis in a haplo-diploid organism: the
invasive ant Wasmannia auropunctata. Some of the populations of this
species have a classical haplo-diploid sexual mating system. In other
populations, females and males are produced through parthenogenesis and
androgenesis, respectively, whereas workers are produced sexually. We
conducted laboratory reciprocal-cross experiments with reproductive
individuals from both types of populations and analyzed their progenies
with genetic markers, to determine the respective contribution of males
and females on the production of androgenetic males. We found that
androgenesis was a parthenogenetic female trait. A population genetic
study conducted in natura confirmed the parthenogenetic female origin of
androgenesis, with the identification of introgression events of sexual
male genotypes into androgenetic/parthenogenetic lineages. We argue that
by producing males via androgenesis, parthenogenetic queen lineages may
increase and/or maintain their adaptive potential, whilst maintaining the
integrity of their own genome, by occasionally acquiring new male genetic
material and avoiding inbreeding depression within the sexually produced
worker cast.