Crazy reproduction in crazy ants
| Ant societies are characterized by a reproductive division of labor and haplodiploid sex determination mechanism. In most species, females are produced by sexual reproduction and develop into queens or workers depending on environmental factors, while males develop from unfertilized, haploid eggs. The combination of eusociality and haplodiploidy has, however, led to the emergence of unusual reproductive strategies in several ant taxa. In the longhorn crazy ant, Paratrechina longicornis, our analyses revealed that all queens and males around the globe belong to two separate, non-recombining clonal lineages. Queens are clones of their mothers, while males are clones of their fathers. By contrast, workers are all first-generation inter-lineage hybrids. This unusual genetic system may have pre-adapted this invasive ant for global colonization by maintaining heterozygosity in the worker force, thus alleviating genetic bottlenecks. We recently discovered another unique reproductive system in the yellow crazy ant, Anoplolepis gracilipes. Males of this species are all chimera of haploid cells from divergent lineages. Chimerism occurs when parental nuclei bypass syngamy and divide separately within the same egg. When syngamy occurs, the diploid offspring either develops into queen or worker females depending on the genotype of the sperm. Genetic analyses suggest that this unusual mode of reproduction is probably the result of a genetic conflict between a bisexual lineage and an androgenetic lineage. |