Short-term cost of outbreeding
The survival of the 231 inbred and 600 outbred colonies was assessed
every two days for 14 days after pairing. The additional 590 colonies
were not used for this experiment because they were only monitored once
a month (see below). For each unsuccessful colony (i.e., at least
one reproductive died), the sex of the dead alate was assessed to
determine its colony of origin. Survival distributions were compared
between inbred and outbred pairings and between pairings using theCoxph -proportional hazards model implemented in thesurvival package (Therneau & Grambsch 2000) in R. This model was
also used to calculate hazard ratios for each colony pairing. Linear and
logarithmic regressions were performed to determine the relationships
between the hazard ratio of each pairing and the effect of the
relatedness between partners (microsatellite analysis), cumulative
microbial load, maximum microbial load, as well as fungal and bacterial
similarities.