Abstract
BackgroundThe reproductive division of labor of eusocial insects, whereby one or several queens monopolize reproduction, evolved in a context of high genetic relatedness. However, many extant eusocial species have developed strategies that decrease genetic relatedness in their colonies, suggesting some benefits of the increased diversity. Multiple studies support this hypothesis by showing positive correlations between genetic diversity and colony fitness, as well as finding effects of experimental manipulations of diversity on colony performance. However, alternative explanations could account for most of these reports, and the benefits of diversity on performance in eusocial insects still await validation. In this study, we experimentally increased worker diversity in small colonies of the ant Lasius niger while controlling for typical confounding factors.ResultsWe found that experimental colonies composed of workers coming from three different source colonies produced more larvae and showed more variation in size compared to groups of workers coming from a single colony.ConclusionsWe propose that the benefits of increased diversity stemmed from an improved division of labor. Our study confirms that worker diversity enhances colony performance, thus providing a possible explanation for the evolution of multiply mated queens and multiple-queen colonies in many species of eusocial insects.
Highlights
Genetic relatedness plays an important role in the evolution of altruistic behaviors in animals [1]
Such reproductive division of labor evolved in a context of high genetic relatedness, with a single female reproductive mated with a single male [3, 4]
The experimental increase in worker diversity enhanced the production of larvae, but not eggs To measure a potential effect of worker diversity on offspring production we monitored the number of eggs and larvae in experimental colonies with low and high worker diversity
Summary
Genetic relatedness plays an important role in the evolution of altruistic behaviors in animals [1]. Extreme altruism is found in colonies of eusocial Hymenoptera (ants, bees and wasps), where the workers forgo their own reproduction to help the queens produce offspring [2] Such reproductive division of labor evolved in a context of high genetic relatedness, with a single female reproductive mated with a single male [3, 4]. Many extant eusocial species have developed strategies that decrease genetic relatedness in their colonies, suggesting some benefits of the increased diversity. Multiple studies support this hypothesis by showing positive correlations between genetic diversity and colony fitness, as well as finding effects of experimental manipulations of diversity on colony performance. We experimentally increased worker diversity in small colonies of the ant Lasius niger while controlling for typical confounding factors
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