1 ǀ Introduction
In many animals, offspring dispersal is critical to avoid local resource
competition and the risk of inbreeding. Given that dispersal is often
dangerous and young individuals have limited knowledge about the
specific conditions in their surroundings, parents may assist their
young during dispersal. For example, poison frogs may transfer tadpoles
from land to water (Pašukonis et al., 2019), wolf spiders may carry
spiderlings (Bonte et al., 2007), and mother bats teach their offspring
to navigate and find suitable habitats (Goldshtein et al., 2022).
Similarly, in several species of ants, workers accompany and even carry
young queens during the founding of new colonies away from their natal
nests (e.g., Möglich & Hölldobler, 1974; Fernández-Escudero et al.,
2001; Peeters & Aron, 2017).
In the ant Cardiocondyla elegans, workers may carry their female
sexual sisters over several meters and dump them into the nest entrance
of another colony. We have argued that this peculiar behavior
constitutes a type of assisted dispersal and mate choice, allowing young
queens to outbreed with several unrelated males away from their natal
nests (Vidal et al., 2021). The ant genus Cardiocondyla is
characterized by an ancestral male polyphenism with winged disperser
males and wingless “ergatoid” males, which locally mate with female
sexuals eclosing in their natal nests. Colonies of most tropicalCardiocondyla are relatively small, with only a few dozen workers
and one or several queens. Individual wingless males are therefore
capable of monopolizing mating with all female sexuals by aggressively
excluding other males with their shear- or sickle-shaped mandibles. In
contrast, colonies of Palearctic species are typically much larger, with
several hundred workers and obligatorily a single, multiply mated queen.
Furthermore, female sexuals are produced not year-round as in the
tropics but seasonally. Because of this, wingless males are no longer
capable of individually securing copulations with all female sexuals and
indeed have evolved mutual tolerance (Heinze, 2017). As mating occurs in
the natal nest, inbreeding coefficients determined from microsatellite
genotypes are relatively high. Nevertheless, data suggest that 40 to 80
% of matings involve unrelated sexuals (Schrempf et al., 2005; Lenoir
et al., 2007; Schrempf, 2014; Vidal et al., 2021), and observations in
the field revealed that in C. elegans these are facilitated by
“royal matchmaking” by the workers, which transfer female sexuals
between unrelated nests.
Here, we follow up on our earlier studies and provide new data about
queen carrying in the field, the relatedness among carrier and carried
ants, and the growth rate of colonies started by individual queens after
mating only with brothers, one or multiple unrelated males. We expected
that outbreeding and multiple mating are reflected in a better
performance of colonies, i.e., faster colony growth.
2 ǀ Material and Methods