I am broadly interested in questions related to how evolution shapes diversity within plant and bacterial populations.  We are currently working primarily on questions related to evolution in symbiotic systems, but I remain interested in questions related to local adaptation, the population genomics  of bacteria, and evolution in urban environments.  We use, and often integrate, manipulative experiments with population genomic analsyes. 

Currently, most of our work is focused on Coevolution in the Medicago truncatula - Ensifer (Sinorhizobia) symbiosis

Using extensive genomic data (full genome data for hundreds of Medicago plants and hundreds of Ensifer strains) we have been characterizing selection acting on both annotated symbiosis genes (in both the plant host and rhizobial symbiont) as well as genes that association genetics analyses have identified as candidates underlying variation in the fitness consequences of symbiosis.  Our goals in this are two-fold, one is to understand the genomics that underly interactions between plant hosts and microbial symbionts, the second to determine the extent to which symbiotic relationships drive coevolution. 

Please contact me If you are interested in learning more about our work or in post-doc or graduate student opportunities.


Recent research

Adaptation and evolution in urban environments

Urban environments are interesting habitats to investigate evolutionary processes and provide an opportunity to investigate how species are affected by heavily altered environments. We have been investigating whether and how plant populations have adapted to urban environments and how fragmentation and population structure may affect such adaptation.  

Population Genomics and in Populus balsamifera

Matt Olson (Univ. of Alaska, Fairbanks) and I used population genetic analysis to identify genes and characterize the evolutionary history of genes likely involved in adaptation of Populus to northern latitudes.  We have also collaborated with Miki Balint and Imke Schmitt in characterizing the foliar fungal microbiome of this species, and the relative importance of the environment and host genotype in shaping that microbiome. 

Ecological and Evolutionary Limits to Species Range Expansion

Monica Geber at Cornell University, Vince Eckhart at Grinnell College, and Dave Moeller at University of Georgia. and I are using Clarkia xantiana (an annual plant native to the southern Sierra Nevada Mountains) to investigating the geographic limits to species range, a fundamental and long-standing problem in ecology and evolution. We are using i) demographic censuses and seed bank experiments to investigate demographicstochasticity, ii) GIS-based niche modeling to characterize suitable habitat; molecular population genetics to evaluate historical population structure, effective population sizes, and gene flow, and iv) reciprocal common-garden experiments to quantify selection and genetic variance across a species range. The results from this series of experiments will provide insight into the basic processes that determine species ranges and provide an opportunity to evaluate predictions from theoretical models predicting limits to local adaptation.

Peter Tiffin
612 624-7406

Head and Professor, Dept. of Plant and Microbal Biology
Univ. of Minnesota
250 Biosciences
St. Paul, MN 55108

Graduate Faculty:
Ecology, Evolution, and Behavior, and Plant and Microbial Biology