Distribution and evolution of genetic caste determination in Pogonomyrmex seed-harvester ants

Kirk E. Anderson, Juergen Gadau, Brendon M. Mott, Robert A. Johnson, Annette Altamirano, Christoph Strehl, Jennifer Fewell

    Research output: Contribution to journalArticle

    49 Citations (Scopus)

    Abstract

    We examined the distribution and ancestral relationships of genetic caste determination (GCD) in 46 populations of the seed-harvester ants Pogonomyrmex barbatus and P. rugosus across the east-to-west range of their distributions. Using a mtDNA sequence and two nuclear markers diagnostic for GCD, we distinguished three classes of population phenotypes: those with GCD, no evidence of GCD, and mixed (both GCD and non-GCD colonies present). The GCD phenotype was geographically widespread across the range of both morphospecies, occurring in 20 of 46 sampled populations. Molecular data suggest three reproductively isolated and cryptic lineages within each morphospecies, and no present hybridization. Mapping the GCD phenotype onto a mtDNA phylogeny indicates that GCD in P. rugosus was acquired from P. barbatus, suggesting that interspecific hybridization may not be the causal agent of GCD, but may simply provide an avenue for GCD to spread from one species (or subspecies) to another. We hypothesize that the origin of GCD involved a genetic mutation with a major effect on caste determination. This mutation generates genetic conflict and results in the partitioning and maintenance of distinct allele (or gene set) combinations that confer differences in developmental caste fate. The outcome is two dependent lineages within each population; inter-lineage matings produce workers, while intra-lineage matings produce reproductives. Both lineages are needed to produce a caste-functional colony, resulting in two reproductively isolated yet interdependent lineages. Pogonomyrmex populations composed of dependent lineages provide a unique opportunity to investigate genetic variation underlying phenotypic plasticity and its impact on the evolution of social structure.

    Original languageEnglish (US)
    Pages (from-to)2171-2184
    Number of pages14
    JournalEcology
    Volume87
    Issue number9
    DOIs
    StatePublished - 2006

    Fingerprint

    Pogonomyrmex
    caste determination
    caste
    ant
    seed
    seeds
    Pogonomyrmex barbatus
    phenotype
    harvester ants
    distribution
    Pogonomyrmex rugosus
    mitochondrial DNA
    mutation
    interspecific hybridization
    social structure
    phenotypic plasticity

    Keywords

    • Caste
    • Cryptic species
    • Dependent lineages
    • Genetic caste determination
    • Genetic conflict
    • Heterozygosity
    • Negative frequency dependent selection
    • Pogonomyrmex

    ASJC Scopus subject areas

    • Ecology

    Cite this

    Distribution and evolution of genetic caste determination in Pogonomyrmex seed-harvester ants. / Anderson, Kirk E.; Gadau, Juergen; Mott, Brendon M.; Johnson, Robert A.; Altamirano, Annette; Strehl, Christoph; Fewell, Jennifer.

    In: Ecology, Vol. 87, No. 9, 2006, p. 2171-2184.

    Research output: Contribution to journalArticle

    Anderson, Kirk E. ; Gadau, Juergen ; Mott, Brendon M. ; Johnson, Robert A. ; Altamirano, Annette ; Strehl, Christoph ; Fewell, Jennifer. / Distribution and evolution of genetic caste determination in Pogonomyrmex seed-harvester ants. In: Ecology. 2006 ; Vol. 87, No. 9. pp. 2171-2184.
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