DISSERTATION RESEARCH: Biome conservatism in Neotropical plant diversification? A case study in Bignoniaceae

University Of Washington, Seattle WA

Investigators

Abstract

Species diversity increases latitudinally from the poles to the equator, making the tropical regions the most species rich on Earth. New World tropical plants - from Mexico to Argentina - harbor an unprecedented 37% of vascular plant species. One of the reasons for this high diversity may lie in the history of the area. South America was isolated from other continental landmasses until about 3 Mya when the isthmus of Panama closed. During this period, geological events and global climate change led to the formation and maintenance of many biomes, creating a heterogeneous landscape with new ecological opportunities for members of the isolated plant assemblage to adapt. This research will generate genetic and environmental data from a group plants with a Neotropical distribution. The goal of this work is to better understand how the evolutionary patterns in each biome combine to generate this unparalleled level of plant diversity. This work will help document existing biodiversity in the Neotropics and foster collaboration with Latin American scientists. Research findings will be communicated via publications and to the broader public by participation in museum exhibits and online media. The focus of this work is to explore the balance of two evolutionary patterns - biome conservatism versus biome shifting- and how it has affected Neotropical plant diversification through space and time. Biome conservatism is the tendency of plant groups to remain in similar environments and retain corresponding ecological traits as they diversify. This pattern implies that evolutionary success through diversification may come primarily from biome expansion through time or long distance migration from point of origin to similar biomes. Alternatively, shifts into novel biomes- biome evolution- could be critical in driving high diversification rates by providing access to new ecological niches to which plant species can adapt. To unravel patterns of biome conservatism and biome shits in the Neotropics, field work will be conducted in Brazil and Colombia to collect members of the large Neotropical plant family Bignoniaceae. Using high-throughput amplicon-based sequencing techniques and statistical phylogenetic analyses, the goals are this project are to (A) detect early diversification events in Bignoniaceae and (B) estimate diversification rates and correlate biome conservatism and biome shift events with these diversification rates across the family. Based on the importance of niche availability to adaptation, increased opportunities available in newly occupied biomes may facilitate significant increases in speciation and diversification rate following biome shifts.