Relatedness between colonies of origin
For each stock colony, DNA from 10 workers was extracted using a modified Gentra PureGene protocol and genotyped at nine microsatellite loci (Aguero et al. 2021b). Amplifications were carried out in a volume of 10µl including 1U of HS DNA polymerase, 2µl of 5x buffer (MyTaq™, Bioline), 0.08µl of each primer, and 1.25µl of DNA template. PCR was performed using thermocycler T100 (Bio‐Rad). Alleles were sized against a LIZ500 standard on an ABI 3500 genetic analyzer (Applied Biosystems) and called using Geneious v.9.1 (Kearse et al. 2012).
Relatedness coefficients (r ) among nestmates and between workers from each pair of colonies were estimated using the Queller and Goodnight (Queller & Goodnight 1989) algorithm implemented in the program COANCESTRY v.1.0 (Wang 2011). Relatedness coefficients were weighted equally, and standard errors (SE) were obtained by jackknifing over colonies. A principal component analysis (PCA) was performed on the microsatellite markers using the adegenet package (Jombart 2008) in R (R Development Core Team 2016) to visualize and confirm genetic differentiation between sampled colonies (Figure S1).