Evolution of an Alpine Flora
I am interested in understanding the evolution and biogeography of the high Andean flora. Like the South American Valerianaceae, there are a number of plant groups whos center of diversity is in the high elevations of the Andes. By inferring phylogenies for a number of these groups, I hope to gain a better understanding for how this ecosystem as come to be so diverse (~60 percent of species are endemic!).
A recent focus in my lab has been a meta-analysis of the origin and diversification of the high-elevation Andean flora. Phylogenetic studies of multiple plant clades from the Andean alpine tundra provide a unique opportunity to investigate evolutionary processes that are potentially responsible for the great diversity in species found in tropical, high-elevation environments.
By looking at a variety of different plant clades, we are addressing several questions:
-Are there regions and habitats where speciation and extinction rates have been significantly higher than in others?
-Have most species originated in situ, or are they primarily immigrants from neighboring areas/habitats? Has there been a dominant directionality of migration (e.g., from north to south, low elevation to high elevation)?
-Can historical barriers (Huancabamba Depression or Arid Diagonal) be detected in molecular phylogenies?
-Among several factors hypothesized to drive species diversification (key innovations, habitat shifts, polyploidy), are any of these correlated with significant increases in diversification rates in the high Andes?
In addition to phylogenetic data, we are collecting georeference data, at the species level, to construct ecological niche models to help us further test hypotheses of species diversification
Molecular phylogenetic data, along with fossil information, will hopefully allow me to infer a temporal framework for the make up of this ecosystem as well.