i. Survival and productivity of incipient colonies
The survival of the 1421 incipient colonies (521 inbred and 900 outbred) was assessed every month for 15 months. Survival distributions were compared between pairs of colonies of origin, as well as between inbred and outbred pairings using the Coxph model. The productivity of all surviving colonies was assessed monthly by counting the number of eggs, workers and soldiers. The difference in productivity between inbred and outbred pairings was determined using two generalized mixed models implemented in the lme4 package (Bates et al. 2015) in R. The models tested the relationship between the numbers of workers and soldiers present in colonies as a function of time (fixed effect), with the type of pairing (inbred or outbred) tested as a random effect. The number of eggs present in a colony was not used because of its bimodal distribution (absence during winter) and non-cumulative nature (eggs ‘disappear’ once they hatch).