Natural history collections provide a unique opportunity to study evolution and ecological change across time. Our lab uses herbarium specimens as historical biological samples, combining collections-based research with modern molecular and genomic approaches to reconstruct past fungal populations, distributions, and host associations. Specimens collected decades or even centuries ago allow us to directly sample biological diversity from periods that cannot otherwise be observed.

A major focus of our research is developing and applying approaches for recovering genetic information from historical fungi. In one study, we sequenced 87 rust specimens spanning more than two centuries, including an approximately 211-year-old specimen, the oldest herbarium specimen from the Kingdom Fungi known to have been sequenced at the time (Bradshaw et al. 2023, New Phytologist). These historical samples revealed spatial and temporal population structure and provided evidence for changes associated with the movement of a fungal lineage between its native and introduced ranges. Earlier work similarly demonstrated how herbarium specimens can be used to reconstruct changes in fungal pathogen populations and invasion histories through time (Bradshaw & Tobin 2020, Plant Disease; Bradshaw et al. 2021, Fungal Biology).

We have since expanded these approaches to large historical datasets spanning hosts, continents, and more than a century of collection. Using 173 herbarium specimens collected across 28 countries, for example, we reconstructed the evolutionary and geographic history of the blueberry powdery mildew complex and found evidence that lineages associated with cultivated blueberries spread globally from eastern North America alongside their hosts (Bradshaw et al. 2025). Historical collections can therefore reveal when lineages appeared in new regions, how their distributions changed, and how populations and host associations have changed through time.

Through our work with the Larry F. Grand Mycological Herbarium and collections around the world, we are transforming preserved specimens from static records of biodiversity into temporal datasets for evolutionary biology. By connecting specimens, genetic data, hosts, geography, and collection dates, we can examine fungal evolution across timescales extending far beyond what is possible through contemporary field sampling alone.