Our research in plant systematics mostly targets Cyperaceae (sedges). This cosmopolitan family contains more than 5600 species found in all biomes, and with large number of representatives from the tropics to the arctic. Cyperaceae are especially abundant and species-rich in temperate areas, mostly because of Carex (>2000 species), the largest botanical genus in Canada, and one of the largest in the world.
Here are a few of our ongoing projects:
The origins of the largest plant genus in North America (Carex)
Due to its great abundance and species richness in wetlands and forest understories throughout the Northern Hemisphere, Carex is one of the best-studied plant genera in the world. Despite this, more than a century of research had failed to support its phylogenetic position within Cyperaceae, or to identify its ancestral distribution (“center of origin”). The large number of species, cosmopolitan distribution and unusual floral features (unisexual flowers, fertile prophyll = perigynium/utricle) all contributed to complexify studies on its evolutionary and biogeographic origins.
Our previous work based on morphological and genetic evidence (DNA), and an extensive taxonomic sampling of temperate Cyperaceae, demonstrated that the closest living relative of Carex is a genus endemic to southeast Asia: Sumatroscirpus (Léveillé-Bourret et al. 2014, 2018a, 2018c). Our field and herbarium studies also revealed that this genus, which was previously thought to contain a single species endemic to Sumatra, actually represent four species also found in China, Myanmar and Vietnam (Léveillé-Bourret et al. 2018b). This discovery will have a lasting impact on our understanding of evolution within one of the largest plant genera in the world, notably by demonstrating yet again the crucial role of southeast Asia in the evolution of temperate plants (Martín-Bravo et al. 2019).
We are planning to continue exploring southeast Asia to study the biology of Sumatroscirpus and early-diverged lineages of Carex, in order to discover the traits and conditions that led to the amazing northern diversification of Carex.
Collaborators: Bruce Ford, Julian Starr, Nguyên Thị Kim Thanh, Vũ Anh Tài
We are also in the process of creating the first complete database of fossil Cyperaceae fruits (>1700 pre-Pleistocene fossils) to enable their use for the estimation of speciation and extinction rates in Carex and other Cyperaceae.
Collaborateurs: Pedro Jiménez-Mejías, Andrea Meseguer, Julian Starr (and several others)
Taxonomy of Carex sect. Lupulinae
Carex sect. Lupulinae is a group of six species endemic to eastern North America that is easy to recognize due to inflated perigynia (utricles) longer than 1 cm long – among the largest in the world. They are very common in swampy areas from southern Quebec down to Louisiana, and three previous taxonomic revisions are in perfect agreement on species limits. Nevertheless, our recent studies (unpublished results) suggest previously unrecognized or underestimated rates of hybridization and introgression, and a few other surprises. Étienne Lacroix-Carignan started a MSc in our group in September 2021 to undertake a new taxonomic revision of this section, using phylogenomic and morphometric approaches. He will re-evaluate species limits, estimate the frequency of hybridization in mixed populations, and perhaps even describe a new species? What is certain is that we are eager to start hunting Carex with him in southeastern USA!
Collaborators: Robert Naczi, Julian Starr
