Selection may favour traits throughout an individuals lifetime or at a particular life stage. In many species of social insects, established colonies that are more genetically diverse outperform less diverse colonies with respect to a variety of traits that contribute to fitness, but whether selection favours high diversity in small colonies is unknown. We tested the hypothesis that selection favours genetically diverse colonies during the juvenile period using a multi-year field experiment with the harvester ant, Pogonomyrmex occidentalis. We used controlled matings to generate colonies that varied in genetic diversity and transplanted them into the field. We monitored their survival for seven (the 2015 cohort, N = 149) and six (the 2016 cohort, N = 157) years. Genetically more diverse colonies had greater survival, resulting in significant viability selection. However, in both cohorts survival was not influenced by genetic diversity until colonies were three years old. We suggest that changes in their internal organization enabled colonies to use the benefits of multiple genotypes, and discuss possible mechanisms that can generate this pattern.

The accompanying data give the number of patrilines, the date of transplant and the number of years that the colony survived.  

Colonies were constructed using directed matings and transplanted over two years (2015-2016).  We monitored colonies for survival to establish longevity.  Colonies could survive for a maximum or 7 years (the 2015 cohort) or 6 years (the 2016 transplant cohort).  A sample of 24 workers was genotyped to establish the number of times that the queen mated.  

There is a README file for the dataset.