Dissertation Research: The Evolution of Reproductive Isolation in Neotropical Costus (Costaceae)

University Of Washington, Seattle WA

Investigators

Abstract

0104847 Schemske The proposed research investigates the mechanisms that contribute to species boundaries in two closely related, Neotropical gingers. The study species live in the same tropical forests in Central America, flower at the same time and are pollinated largely by the same species of hummingbird. Yet they differ in a number of leaf and flower characters, and never produce hybrid offspring. What keeps these species distinct? The research will use experimental crosses, field observations and molecular genetic techniques to answer this question. The information gathered thus far suggests that crosses in one direction fail because pollen growth is inhibited, while reproductive failure in the other direction is caused by the inability of the pollen to grow far enough to produce seeds. The research findings will ultimately show the subtle, but effective means that allow different species to coexist. One of the great mysteries of Nature is how species retain their distinctive characteristics. Without mechanisms to prevent interbreeding, the diversity of species would be far less than what we see today. Understanding how these reproductive barriers function in natural populations provides insights useful for both the development of new agricultural varieties and for the conservation and management of biodiversity.