Intraspecific competition for a nest and its implication for the fitness of relocating ant colonies

Abstract

Competitive interaction is important in structuring species composition of a habitat. Several studies have been conducted on intraspecific competition but little is known in the context of the goal-oriented task of colony relocation. Current study examines how relocating colonies respond when the new nest is a limiting resource. Examining this competition across equal sized colonies (n=17) and unequal sized colonies (n=14), we found that most trails had a clear outcome with one of the colonys occupying the new nest, while 25% of colonies merged. Larger colonies had a significantly higher chance of occupying the new nest and outcompeted the smaller colonies in most of the cases. Colonies that had lower latency to discover and more explorers had a significantly higher chance of gaining control of the new nest and interesting the level of aggression shown by both the competing colonies was comparable. Spatio-temporal analysis of the aggression revealed that the area surrounding the old, new nest and the time at which transportation occurs has higher levels of aggression. While both the competing colonies stole pupa from each other, the mean number of successful stealing by the larger colonies was 8 times larger than smaller colonies while stealing was comparable between similar sized colonies. Relocating colonies experienced significantly more mortality as compared to controls and competition for the new nest imposed additional mortality on losing colonies over the short time. Due to the potential merging of colonies, incorporation of stolen brood and increased mortality, the overall fitness of the colonies is likely to be negatively impacted due to intraspecific competition for a new nest.