US-South Africa Dissertation Enhancement: The Evolution of Long-Tongued Fly Pollinators (Diptera: Tabanidae)

University Of California-Davis, Davis CA

Investigators

Abstract

0138288 M. Sanderson This dissertation enhancement grant supports a US graduate student, Ms. Shelah Morita, working under the guidance of Professor Michael Sanderson, in the Section of Evolution and Ecology at the University of California-Davis, to conduct a study in South Africa on the coevolution of long-tongued horse flies (Diptera: Tabanidae) and the deep-throated flowers that they pollinate. The study of coevolution can provide knowledge about the importance of species interactions in speciation, but present day associations between species may not reflect their past relationships. Diptera: Tabanidae is an ideal system for studying coevolution because their unusually long mouthparts are thought to covary with the morphological features of the flowers on which they feed, and it has already been demonstrated that these horse flies are closely tied to the fitness of the endemic flora of the South African fynbos region. But the biogeographical distribution of this group of horse flies does not match the predicted biotic distribution provided by the current understanding of historical biogeography. Ms. Morita hypotheses that: 1) Nectar-feeding Tabanidae in South Africa have coevolved with the plants they pollinate, and 2) Blood feeding is ancestral in female long-tongued horse flies within the tribe Philolichini. She also seeks to learn if the current classification of horse flies correctly represents their evolutionary relationships. Through a unique combination of phylogenetic approach and population-level studies, Ms. Morita will first study the phylogenies of both plants and pollinators, after which she will analyze the coevolution of proboscis length and nectar spur length in order to understand the evolutionary relationships within this group of Tabanidae. The student will use data obtained from field collected samples and institutional specimens. Dr. Steven Johnson, with the School of Botany and Zoology at the University of Natal, is a noted authority on the pollination ecology and plant systematics of this system, and he will provide guidance on this project to Ms. Morita. The results of this study are expected to advance the current knowledge on how animals and plants coevolve and new feeding behaviors are acquired. This project will also support an international research experience very early in the career of an outstanding graduate student. The Office of International Science and Engineering and the Division of Environmental Biology jointly fund this project.