Queen-Queen Competition by Precocious Male Production in Multiqueen Ant Colonies

Abstract

Arriving earlier in the breeding area than his rivals may be beneficial for a male when females mate only once or during a short time span. The timing of a male's entrance is usually determined by the male himself, e.g., through returning early from his winter quarters or through accelerated larval development . Here, we document a surprisingly simple way of "first come, first served" in a species with local mate competition. In multiqueen colonies of a Cardiocondyla ant, mother queens make sure that their own sons are the first to monopolize mating with a large harem of female sexuals by producing extremely long-lived males early in colony life. Whereas queens in newly founded single-queen colonies started to produce male and female sexuals only several weeks after the eclosion of their first worker offspring, queens in multiqueen colonies precociously reared sons long before the first female sexuals and even before the emergence of their first workers. These early males killed all later emerging males in the nest and mated with all female sexuals subsequently produced. Our data document that the patterns of growth and productivity of insect colonies are surprisingly flexible and can be turned upside down under appropriate selection pressures.

Aging and Reproduction in Social Insects – A Mini-Review

“…In contrast to all other studied social Hymenoptera, spermatogenesis continues in these fighter males [67] and they are also considerably more long-lived than other ant males. In one extreme case, males have been observed to survive and monopolize matings for more than a year [68] . This documents that under appropriate selection pressure the lifespan of males can be surprisingly long.…”

“…Senescence obviously starts with foraging: workers show a decline in physiological resistance to stress, such as heat, desiccation, and starvation [21] and their hemocyte count drops [22] , while their behavioral performance appears to remain unchanged [23] . On the other hand, an experimental increase in intrinsic mortality Lifespan of queens in multi-queen societies is shorter than that of queens in single-queen societies [2] Workers with high extrinsic mortality live less long than task workers inside the hive [26] Males of social insects have a short lifespan, in accordance with their short reproductive phase; wingless males of the ant genus Cardiocondyla, whose spermatogenesis is prolonged, live considerably longer [68] Rate of aging increase with the level of extrinsic mortality s by exposing honey bee or ant workers to CO 2 or other stressors leads to precocious foraging [24,25] , i.e., the highly plastic course of behavioral ontogeny can be manipulated by changing the internal status. In worker-polymorphic ants, in which different size classes of workers engage in different tasks in or outside the nest, lifespan again varies with task-specific extrinsic mortality.…”

Lifespan in male ants linked to mating syndrome

“…The lifespan of aggregating males may thus be underestimated if they must wait for nuptial flights that are synchronized across nests . In an extreme case, wingless males of the ant genus Cardiocondyla never disperse, and may live more than a year within the natal nest, defending harems of females (Yamauchi et al, 2006). In addition, female calling species are typified by small colony size, low population density, and social parasitism (Hölldobler and Bartz, 1985;Bourke and Franks, 1995;Mori et al, 2001).…”

Life-history evolution in ants: the case ofCardiocondyla

“…Cardiocondyla are thus amenable to experimental studies that are difficult to do with other social insects. For example, the relatively short lifespan of Cardiocondyla queens (a few months in polygynous, tropical species [82], more than 1 year in monogynous species [43,70]), allows investigation of lifetime reproductive success and age-specific mortality, fecundity and sex ratios.…”

“…the Palaearctic clade) or when wingless males are extremely long-lived (e.g. [70]). Both phenomena make it very unlikely that colonies contain female sexuals without a resident wingless male.…”