Virgin ant queens mate with their own sons to avoid failure at colony foundation

Abstract

Mother-son mating (oedipal mating) is practically non-existent in social Hymenoptera, as queens typically avoid inbreeding, mate only early in life and do not mate again after having begun to lay eggs. In the ant genus Cardiocondyla mating occurs among sib in the natal nests. Sex ratios are extremely female-biased and young queens face the risk of remaining without mating partners. Here, we show that virgin queens of Cardiocondyla argyrotricha produce sons from their own unfertilized eggs and later mate with them to produce female offspring from fertilized eggs. Oedipal mating may allow C. argyrotricha queens to found new colonies when no mating partners are available and thus maintains their unusual life history combining monogyny, mating in the nest, and low male production. Our result indicates that a trait that sporadically occurs in solitary haplodiploid animals may evolve also in social Hymenoptera under appropriate ecological and social conditions.

When invasive ants meet: effects of outbreeding on queen performance in the tramp ant Cardiocondyla itsukii

“…However, inbreeding in social Hymenoptera may result in the production of diploid males from fertilized eggs due to homozygosity at the sex‐determining locus (van Wilgenburg et al ., ). In C. obscurior and also other species of this genus, inbreeding is the rule and neither brother–sister nor mother–son mating leads to diploid males (Schrempf et al ., ; Schmidt et al ., ). Though we do not have exact data on the consequence of prolonged inbreeding in C. itskuii , the percentage of eggs developing into males in inbred colonies was much lower than the 50% expected from single‐locus complementary sex determination.…”

Methuselah’s daughters: Paternal age has little effect on offspring number and quality in Cardiocondyla ants

“…Four‐week‐old queens therefore can still be considered as “young,” even though they would have mated long before if a male had been present. Even without mating, virgin queens may shed their wings within a few weeks after emergence and begin to mature eggs (Schrempf, Heinze, & Cremer, ; see Schmidt, Frohschammer, Schrempf, & Heinze, for mother–son mating in a related species). Nevertheless, because a long premating time reduces the period during which queens can lay fertilized eggs (e.g., Fuester, Swan, Taylor, & Ramaseshiah, ), we expected a small negative influence of prolonged virginity on reproductive performance.…”

Life-history evolution in ants: the case ofCardiocondyla

“…Genetic data show that in species with only wingless males up to 95% of all matings involve close relatives [47][48][49]56]. Neither brother-sister mating nor mother-son mating lead to the production of diploid males [57,58], suggesting that Cardiocondyla has evolved an alternative to sl-CSD. A recent study documented sex-specific splicing of transformer, a key player in insect sex determination, but it is still unclear what initially triggers the development of males from unfertilized eggs and females from fertilized eggs [59].…”