RUI: A Phylogenomic Approach to Understanding the Symbiosis Between Acropyga Ants and Xenococcine Mealybugs

Towson University, Towson MD

Investigators

Abstract

A major question in evolutionary biology is how different kinds of organisms can form and maintain mutually beneficial relationships over long periods of time, often with conflicting self-interests. This project will use state-of-the-art techniques to study an insect agriculture system to understand the evolutionary bonds between Acropyga ants and mealybugs. Acropyga ants are herder ants that use mealybugs in a similar way humans use diary-cattle. The ants keep the mealybugs in their nests, place them on underground plant roots to feed, and then the ants feed on honeydew (fluid) the mealybugs excrete through specialized pores. By reconstructing the evolutionary relationships of the ants and mealybugs it will be investigated whether or not the two partners have influenced each other's species diversity over time. The ant - mealybug system is a powerful model system to contribute to a broader understanding of the evolution of mutualisms among species. This project will also provide research training in taxonomy and systematics to undergraduate and graduate students, engage K-12 teachers with training to improve K-12 science education, and contribute to scientific infrastructure through collections and publicly accessible websites (e.g., AntWeb). The primary research goals of this study are twofold: 1) conduct phylogenomic studies of Acropyga ants and xenococcine mealybugs using genomics level data (ultraconserved elements) and 2) use the phylogenies to test for codiversification between lineages. The production of robust phylogenies using a phylogenomic approach to capture and sequence, using next-generation sequencing, ultraconserved elements from the two insect partners in this system will provide data at multiple evolutionary timescales. The vertical transmission of mealybugs across ant generations via trophophoresy and the high specificity of xenococcine species inhabiting ant nests both lead to the expectation of codiversification between the partners. We will test three hypotheses: 1) weak partner fidelity (null); 2) diffuse-sense codiversification; and 3) strict-sense codiversification. We will utilize both permutation and event-based methods to test for significant levels of cospeciation between ant and mealybug phylogenies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.