SG: Phylogeny, Biogeography, and Revision of Lobelia in the Mexican Transition Zone

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

The five major mountain ranges in Mexico called the Mexican Transition Zone provide a unique opportunity to study the relationships of closely related species that are restricted to a single range. These mountains are a transition zone because they have a mix of organisms from the temperate parts of the Americas as well as from the tropics. The target organism for the project will be the plant genus Lobelia. There are 90 species in the mountains of Mexico and, of those, 83 are found only there. Most of the species have small, blue flowers and are insect-pollinated, but six have large, red flowers that are hummingbird-pollinated. Both groups have species with a unique floral feature, a nectar spur, found nowhere else in the world. This project will reconstruct the evolutionary relationships of the Mexican Lobelias to investigate how they are related to each other and to species in other parts of North and South America and will help determine whether hummingbird pollination and nectar spurs have evolved independently multiple times. First generation and underserved graduate and undergraduate students will be trained in molecular techniques and museum studies. The research will strengthen international collaborations among a Mexican specialist with intimate knowledge of the species from field work, students, and researchers. Outreach materials will be developed collaboratively and incorporated into a permanent public display and showcased at a booth at Louisiana State University’s monthly Night at the Museum event. Specimens collected and discoveries made will also be incorporated into courses taught at Northern Arizona University. Molecular data gathered from chloroplast genomes and a nuclear probe set developed for a closely related group will be used to build a comprehensive phylogenetic framework for the plant genus Lobelia, focusing on the highly diverse and endemic lineages of Mexico. This framework will be used to answer broad evolutionary questions about biogeography, pollinator shifts, and hybridization. A time-calibrated tree will also be produced to test specific biogeographic hypotheses in the Mexican Transition Zone including: 1- geographic barriers between lineages, 2- long-distance dispersal between mountain ranges, and 3- biogeographic patterns associated with pollination syndrome or presence of nectar spurs. The revisionary work produced by this collaboration and multiple undergraduates will include publicly available descriptions, images, photos, and an interactive web key to all Lobelia species in Mexico and Central America, all of which will serve as a resource for current and future floristic inventories. 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.