Related Experiment Videos
Sex allocation conflict in ants: when the queen rules
Hervé Rosset1, Michel Chapuisat
1Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
Current Biology : CB
|February 8, 2006
Summary
In ants, queens control colony sex ratios by laying biased eggs, leading to specialization in male or female production. Workers can still manipulate brood, resulting in a compromise sex ratio.
Area of Science:
- Evolutionary biology
- Behavioral ecology
- Social insects
Background:
- Ant colonies exhibit cooperation but also internal conflicts over resource allocation, particularly sex allocation.
- The haplodiploid sex-determination system creates differing relatedness asymmetries between queens and workers to sons and daughters.
- Workers typically favor females, while queens are indifferent, leading to potential conflicts over sex ratios.
Purpose of the Study:
- To investigate the role of queens in determining colony sex allocation in the ant species Formica selysi.
- To understand the interplay between queen control over egg-laying and worker manipulation of brood sex ratios.
- To determine the equilibrium of sex investment in ant colonies.
Main Methods:
- Analyzing the sex ratio of eggs laid by queens in relation to colony specialization (male or female production).
- Comparing the sex ratio at the egg stage with that at the pupal stage to detect worker manipulation.
- Calculating the population sex-investment ratio to compare with theoretical equilibria.
Main Results:
- Queens of Formica selysi significantly influenced colony sex allocation by biasing egg sex ratios, with most colonies specializing in one sex.
- Queens in female-specialist colonies laid predominantly diploid eggs, while queens in male-specialist colonies laid mostly haploid eggs.
- Worker manipulation was evident, as the sex ratio shifted from egg to pupal stage, resulting in a population sex-investment ratio intermediate between queen and worker optima.
Conclusions:
- Queens exert a prominent influence on colony sex allocation through their control of egg sex ratio, often leading to sex specialization.
- An ongoing conflict exists between queens and workers regarding sex allocation, with queens' control over egg-laying being a key factor.
- Worker manipulation of brood occurs, but the final sex-investment ratio reflects a compromise shaped by both queen and worker interests.