# Frequent Queen Replacement and Presence of Unrelated Queens in Colonies of a Functionally Monogynous Ant Species

## TL;DR

This study explores how queen replacement and unrelated queens affect colony dynamics in a type of ant that typically has one queen.

## Contribution

The study reveals that unrelated queens can invade nests but are limited in reproducing, offering insights into social parasitism in ants.

## Key findings

- Multiple queens with developed ovaries can coexist in the same nest.
- Dominant queens are frequently replaced by relatives.
- Alien queens without developed ovaries invade nests but do not reproduce.

## Abstract

In eusocial insects, social parasitism—the exploitation of the host's brood care behavior for survival and reproduction—can occur either within or between species. Parasitic queens invade host nests and aggressively replace the resident queen. While the adoption of conspecific queens is a common feature of species with multiqueen colonies (polygyny), the origin of parasitic founding is not fully understood. Functionally monogynous ants, in which nestmate queens establish social and reproductive hierarchies through biting and antennal boxing, may provide a link between peaceful adoption and social parasitism. In this study, we investigated whether alien queens can usurp colonies of the functionally monogynous ant
Leptothorax gredleri
. Ovary dissection of queens from 33 nests showed that multiple queens with developed ovaries can occasionally co‐occur in the same nest. Genetic analysis revealed frequent replacement of the dominant queens by relatives. Instead, alien queens rarely take over reproduction, suggesting a few occurrences of intraspecific social parasitism. However, the data suggest that alien queens without developed ovaries frequently invade nests without being eliminated. This suggests that alien queens are somehow prevented from reproducing and social parasitism is therefore limited in this species.

In this study, we investigated whether alien queens can usurp colonies of the functionally monogynous ant
Leptothorax gredleri
. Using ovary dissection of queens and genetic analyses, we showed that multiple queens with developed ovaries can occasionally co‐occur in the same nest, with a frequent replacement of the dominant queens by relatives. Instead, alien queens rarely take over reproduction, but alien queens without developed ovaries frequently invade nests without being eliminated, suggesting that alien queens are somehow prevented from reproducing and social parasitism is limited in this species.