ants and Infertility

Many ant species have complex caste systems, with reproductive queens and sterile workers, which often play distinct roles in the maintenance and defense of the colony. A new study sheds light on how these worker caste systems evolved and the mechanisms by which totipotent larvae give rise to the alternative adult castes.

Topics: Animals; Ants; Infertility; Larva; Reproduction

Kin selection is thought to drive the evolution of cooperation and conflict, but the specific genes and genome-wide patterns shaped by kin selection are unknown. We identified thousands of genes associated with the sterile ant worker caste, the archetype of an altruistic phenotype shaped by kin selection, and then used population and comparative genomic approaches to study patterns of molecular evolution at these genes. Consistent with population genetic theoretical predictions, worker-upregulated genes experienced reduced selection compared with genes upregulated in reproductive castes. Worker-upregulated genes included more taxonomically restricted genes, indicating that the worker caste has recruited more novel genes, yet these genes also experienced reduced selection. Our study identifies a putative genomic signature of kin selection and helps to integrate emerging sociogenomic data with longstanding social evolution theory.

Topics: Animals; Ants; Behavior, Animal; Biological Evolution; Evolution, Molecular; Family; Genetics, Population; Genomics; Infertility; Metagenomics; Phenotype; Reproduction; Selection, Genetic; Social Behavior

Harvester ants (P. badius) were collected from 49 localities in the southeastern U.S. Amylase and naphthylamidase activities were assayed by gel electrophoresis, and the frequencies of alleles controlling electrophoretic variation were calculated. Soil samples were analyzed and plotted against allelic frequencies. Climatographic and genetic data were analyzed by the method of principal components. Statistically significant correlations were found to occur between the patterns of genetic variation, and between the genetic and environmental patterns. These correlations are consistent with a selective basis for the maintenance of isozyme polymorphisms.

Topics: Amylases; Animals; Ants; Climate; Diploidy; Electrophoresis, Polyacrylamide Gel; Environment; Female; Gene Frequency; Genetic Variation; Genetics, Population; Genotype; Infertility; Isoenzymes; Leucine; Leucyl Aminopeptidase; Male; Mathematics; Polymorphism, Genetic; Soil; United States