2025-07-22 ロックフェラー大学
<関連情報>
- https://www.rockefeller.edu/news/38067-how-ant-queens-are-made/
- https://www.pnas.org/doi/10.1073/pnas.2501716122
クローン性強奪アリにおけるカースト関連形質の静的アロメトリーは遺伝子型によって変化するが、環境によって変化しない Static allometries of caste-associated traits vary with genotype but not environment in the clonal raider ant
Patrick K. Piekarski, Stephany Valdés-Rodríguez, Waring Trible, and Daniel J. C. Kronauer
Proceedings of the National Academy of Sciences Published:July 22, 2025
DOI:https://doi.org/10.1073/pnas.2501716122
Significance
How an individual’s phenotype arises from interactions between its genotype and the rearing environment is an important question in biology. Female ants are a powerful system to study this question because they can develop into divergent types, or castes, such as workers and queens. Here, we show that environmental effects on the caste morphology of individuals are coupled with effects on body size and fail to find evidence for size-independent regulation of caste morphology. Genetic differences, on the other hand, affected both body size and its relationship with caste phenotypes, implying that genotype can influence adult caste morphology either by altering body size or the allometric relationship between body size and caste trait expression.
Abstract
Polyphenic traits in animals often exhibit nonlinear scaling with body size. Static allometries (i.e., scaling relationships) themselves can exhibit plasticity, such that individuals of the same size and genotype differ in body proportions across different environments. In ants, both larval environment and genotype regulate the expression of caste-associated traits, including body size and ovariole number. However, it remains untested whether caste-associated traits are independently regulated by environmental variables or whether they covary due to coupled developmental mechanisms. If caste traits are regulated independently, developmental plasticity should affect both trait expression and the scaling relationships between traits. Using the clonal raider ant, Ooceraea biroi, we tested this by manipulating the rearing environment of genetically identical larvae. We found that caregiver genotype, temperature, and food quantity influenced caste morphology strictly in tandem with body size, producing similar static allometries across rearing conditions (i.e., no allometric plasticity was detected). In contrast, clonal genotypes differed in average body size and their static allometries. Thus, size-matched individuals of the same genotype from different rearing environments exhibited no differences in mean caste trait expression, while those of different genotypes did. This absence of plasticity in the static allometries of different caste traits suggests that they are developmentally coupled due to systemic regulatory factors. Our findings contrast with reports of allometric plasticity in other insects, suggesting that ant caste traits are exceptionally integrated and therefore constrained in their independent responses to environmental variation. We discuss how these results inform contemporary hypotheses for ant caste development and evolution.
