Evolutionary Ecology

, Volume 24, Issue 2, pp 359–374

Shift in frequency-dependent selection across the life-cycle in obligately interbreeding harvester ant lineages

Original Paper

DOI: 10.1007/s10682-009-9311-7

Cite this article as:
Helms Cahan, S. & Julian, G.E. Evol Ecol (2010) 24: 359. doi:10.1007/s10682-009-9311-7


The long-term persistence of hybridogenetic systems, in which one genetic lineage is dependent on another as a sperm host, is paradoxical because they require continual coexistence between ecological competitors. Several species of ants display a social form of hybridogenesis, in which two distinct genetic lineages obligately interbreed to produce sterile workers, while intra-lineage progeny become the reproductives. A recent model suggests that persistence of such a system depends on the relative strengths of negative frequency-dependent selection acting during colony growth and positive frequency-dependent selection during reproduction. We used path analysis to investigate the effect of lineage frequency on reproductive output and colony sex ratio over a single reproductive season in a natural population of the H1/H2 lineage pair in the genus Pogonomyrmex. Results suggest that lineage frequency does impact reproduction via two opposing routes: the more common lineage procures more same-lineage mates, resulting in a higher proportion of same-lineage mates increases reproduction through higher queen-egg availability, but the rarer lineage procures more alternate-lineage mates, yielding a more genetically diverse worker caste that increases productivity. As a result, lineage frequency has only a weakly positive overall effect on colony reproduction, and overall frequency-dependence in this system across the entire life cycle is likely to be negative as predicted by the persistence model.


Genetic caste determinationHybridogenesisFrequency-dependent selectionPogonomyrmexReproductionSex ratio

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.Department of BiologyUniversity of VermontBurlingtonUSA
  2. 2.Department of BiologySouthwestern UniversityGeorgetownUSA