Genetic analysis of two species of Mnomen in the Kalamazoo Watershed reveal panmixia in Z. Aquatica, structure among Z. Palustris, and hybridization in areas of sympatry

Mnomen or wild rice of the genus Zizania is an important part of Native American culture, especially in Michigan for the Ojibwe nation. An oil spill in 2010 along the Kalamazoo River and the subsequent clean-up lead to renewed interest in management of Mnomen within the Kalamazoo watershed. The affected water bodies were surveyed for Zizania species to map existing populations, determine the existing genetic diversity and species present, and to identify potential hybridization. Using Traditional Ecological Knowledge of rice beds and opportunistic sampling of encountered plants, 28 rice beds were sampled. Two species of Zizania were identified Z. palustris and Z. aquatica. Genetic diversity was measured using 11 microsatellite loci and was moderately high for both species (Z. aquatica H(E) = 0.669, H(0) = 0.672, n = 26 and Z. palustris H(E) = 0.697, H(0) = 0.636, n = 57). No evidence of population bottle-necking was found. Z. palustris was found to have k = 3 populations on the landscape, while Z. aquatica was found to be a single panmictic population. Several individual hybrids were confirmed using genotyping and they were all found in areas where the two species co-occurred. Additionally, Z. aquatica was found to have expanded into areas historically with only Z. palustris downstream of the oil spill, potentially due to dredging and sediment relocation as part of the clean-up effort.