When every sperm is sacred: the emergence and decline of superorganismal chimeras

Convergent Reversion to Single Mating in a Wasp Social Parasite

“…Several desert ants (Cataglyphus spp.) have reverted from obligate to facultative polyandry as well, although no ecological or life-history factors associated with these transitions are apparent (Aron et al 2016;Boomsma 2016). Together with A. insinuator (Sumner et al 2004b), all reversions to date have been from obligate polyandry to mating systems with at least some residual multiple mating; D. arctica is the first reversion documented from a facultatively polyandrous ancestor and the first to reevolve obligate single mating.…”

“…2), indicating that D. arctica evolved monandry from facultative polyandry. Most studies addressing the benefits of polyandry in the eusocial Hymenoptera have focused on obligately polyandrous species, and the benefits maintaining facultative polyandry may be different and are currently unknown (Boomsma 2013). The reversion to monandry suggests female rather than male control over mating frequency: D. arctica females differ from queens of closely related species in that they no longer produce workers, while selection on male mating traits is presumably similar in both social and inquiline species.…”

“…The evolution of multiple mating by females (polyandry) has been a major focus of research in evolutionary biology (Taylor et al 2014). The mating systems of social insects have attracted particular interest, given the wide variation in queen mating frequencies across the ants, bees, and wasps; the importance of multiple mating in determining kinselected benefits of altruism to workers; and the remarkable repeated origins of extreme polyandry in a few phylogenetically diverse, highly eusocial taxa (Boomsma and Ratnieks 1996;Crozier and Fjerdingstad 2001;Strassmann 2001;Hughes et al 2008a;Boomsma et al 2009;Boomsma 2013;Jaffé 2014). A variety of hypotheses have been proposed to explain the selective benefits of polyandry in social insects (Crozier and Page 1985;Boomsma and Ratnieks 1996;Crozier and Fjerdingstad 2001).…”

“…Recent phylogenetic analyses (Lopez-Osorio et al 2015;Perrard et al 2015) place D. arctica, like its host, within the subgenus Boreovespula. Most members of the genus, including the host species, exhibit facultative polyandry (Foster et al 2001;Bonckaert et al 2011b;Loope 2015), a mating system in which queens frequently mate singly but also sometimes mate more than once (Boomsma and Ratnieks 1996;Boomsma 2009Boomsma , 2013. It has been argued that facultative polyandry represents a mating syndrome distinct from obligate polyandry (always multiple queen mating), with possibly very different selective pressures maintaining it (Boomsma and Ratnieks 1996;Boomsma 2013).…”

Differential immune-gene expression in sperm storage organs of leaf-cutting ants

“…The perennial social Hymenoptera are exceptional in that breeding females (queens) mate only during a single mating episode early in adult life and store the acquired sperm in a specialized organ, the spermatheca, without ever re-mating once they have started laying eggs (Boomsma et al, 2005a;Boomsma, 2016). This implies that selection pressure for maximizing sperm survival and prudent sperm use can be very strong (Cole, 1983;den Boer et al, 2009a;Baer et al, 2016), particularly in ants whose queens can live for up to two decades (Keller, 1998;Kramer et al, 2016).…”