The coevolution between dispersal and sociality can lead to linked polymorphisms in both traits, which may favour the emergence of supergenes. Supergenes have recently been found to control social organization in several ant lineages. Whether and how these "social supergenes" also control traits related to dispersal is yet unknown. Our goal here was to get a comprehensive view of the dispersal mechanisms associated to supergene-controlled alternative social forms in the ant Formica selysi. We measured the production and emission of young females and males by single-queen (monogyne) and multiple-queen (polygyne) colonies, the composition of mating aggregations, and the frequency of crosses within and between social forms in the wild. We found that males and females from alternative social forms did not display strong differences in their propensity to leave the nest and disperse, nor in their mating behaviour. Instead, the social forms differed substantially in sex allocation. Monogyne colonies produced 90% of the females flying to swarms, whereas 57% of the males in swarms originated from polygyne colonies. Most crosses were assortative with respect to social form. However, 20% of the monogyne females did mate with polygyne males, which is surprising as this cross has never been found in mature monogyne colonies. We suggest that the polygyny-determining haplotype free rides on monogyne females, who establish independent colonies that later become polygyne. By identifying the steps in dispersal where the social forms differ, this study sheds light on the behavioural and colony-level traits linking dispersal and sociality through supergenes.

There are 5 datasets and 1 script for data analyses and figures dispersal_abs_DRYAD.txt = number of female and male alates emitted by field colonies throughout a reproductive season. Figures 1, Figure 2 and S2 dispersal_perday_DRYAD.txt = number of female and male alates emitted by field colonies, by collection date. Figure S4 production_perday_2018_DRYAD.txt = number of female and male alates produced by field colonies, by collection date. Figure S2 swarms_females_DRYAD .txt =list of females captured in mating swarms and offspring production of these females in the lab. Table 1, Table S1, and Figure S1 swarms_males_DRYAD .txt = list of males captured in mating swarms. Table 1 and Table S1 Dispersal_MS_script_summary_02_03_2021 = R script

Funding provided by: Swiss National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001711Award Number: 31003A-173189/1