Molecular regulation of complementary sex determination in the Argentine ant

• Applicant: Dr. Qiaowei Pan
• Subject Area: General Genetics and Functional Genome Biology ; Evolution, Anthropology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 570089330

Sex determination mechanisms vary widely across animals, yet the molecular basis of primary sex determination remains poorly understood, except in a few model systems. Haplodiploidy—a system in which females are diploid and males haploid—has evolved multiple times and occurs in approximately 12% of animal species. Despite its prevalence, the molecular mechanisms underlying haplodiploidy remain largely unexplored. In Hymenoptera (ants, bees, wasps, and sawflies), the ancestral mechanism for haplodiploidy is complementary sex determination, in which heterozygosity at a multi-allelic locus drives female development, while homozygosity or hemizygosity leads to males. Until recently, such a complementary locus had only been identified in the honeybee. We recently discovered an analogous locus in the Argentine ant that harbors seven distinct alleles. Offspring carrying two different alleles develop into females through the expression of a long non-coding RNA we named ANTSR. This project aims to dissect how heterozygosity at this locus elevates ANTSR expression and to explore the locus’s evolutionary dynamics. First, we will generate a comprehensive annotation of the locus to assess the presence of additional regulatory elements, such as small RNAs. We will also investigate whether heterozygosity is detected through physical interactions between homologous chromosomes, similar to transvection mechanisms. Following that, we will study the evolutionary history of the sex locus by analyzing allelic diversity and signatures of selection in native and invasive Argentine ant populations. By uncovering the molecular basis of sex determination in a haplodiploid species, this work will provide new insights into the evolution of sex determination systems.

• DFG Programme: Research Grants