Pleiotropy of segregating genetic variants that affect honey bee worker life expectancy

Abstract

In contrast to many other complex traits, the natural genetic architecture of life expectancy has not been intensely studied, particularly in non-model organisms, such as the honey bee (Apis mellifera L.). Multiple factors that determine honey bee worker lifespan have been identified and genetic analyses have been performed on some of those traits. Several of the traits are included in a suite of correlated traits that form the pollen hoarding syndrome, which was named after the behavior to store surplus pollen in the nest and is tied to social evolution. Here, seven quantitative trait loci that had previously been identified for their effects on different aspects of the pollen hoarding syndrome were studied for their genetic influence on the survival of adult honey bee workers. To gain a more comprehensive understanding of the genetic architecture of worker longevity, a panel of 280 additional SNP markers distributed across the genome was also tested. Allelic distributions were compared between young and old bees in two backcross populations of the bi-directionally selected high- and low-pollen hoarding strain. Our results suggest a pleiotropic effect of at least one of the behavioral quantitative trait loci on worker longevity and one significant and several other putative genetic effects in other genomic regions. At least one locus showed evidence for strong antagonistic pleiotropy and several others suggested genetic factors that influence pre-emergence survival of worker honey bees. Thus, the predicted association between worker lifespan and the pollen hoarding syndrome was supported at the genetic level and the magnitude of the identified effects also strengthened the view that naturally segregating genetic variation can have major effects on age-specific survival probability in the wild.