Regulation, development, and evolution of caste ratios in the hyperdiverse ant genus Pheidole.

Ant colonies are considered complex biological systems because many individuals are divided into different castes that interact to efficiently perform their tasks. Colonies in the hyperdiverse ant genus Pheidole have evolved a worker caste with at least two subcastes: soldiers and minor workers. The proportion of soldiers and minor workers in a colony has a major impact on the colony's fitness and is tightly regulated. Here, we summarize over 100 years of research on the internal, external, and developmental factors that regulate subcaste production as well as influence subcaste evolution in Pheidole. We hope that summarizing these factors into a network of interactions will provide insight into how complex biological systems regulate, develop, and evolve.