It is unclear how the environmental heterogeneity of the prairie biome of North America contributes to the biogeographic ranges of vascular plant species, particularly herbaceous taxa. We examined the spatial distributions of 30 abundant plant species of the grasslands of North America distributed among four functional groups: C 4 grasses, C 3 grasses, forbs, and woody species. For each species, we mapped its distribution using occurrence data from georeferenced herbarium specimens and a species distribution model (MAXENT). We then assessed which of several climate, soil, and elevation variables contribute to determining its range. On average, these 30 plant species are distributed over large areas, with an average range size of 1,989,750 km 2 . Temperature variables contribute the most to the MAXENT model for 27 of the 30 species. Size of range, abruptness of boundary edges, and location of range vary among all 30 species. Functional groups differ primarily in range size and the centroid of the ranges. Conservation of tallgrass, mixed-grass, and shortgrass prairie biomes will require a flexible strategy with widely distributed habitat over the Great Plains along both north-south and east-west gradients. [
The recent declines in eastern North American species of freshwater mussels have been well documented, but the status of western species has been comparatively understudied. However, various local and regional studies and anecdotal observations indicate that western mussels are also declining, suggesting the need for range-wide assessments of extinction risk and changes in freshwater mussel distributions. Using historic (pre-1990) and recent (1990-2015) occurrence data from across western states and incorporating observations of recent population dynamics, we assessed the extinction risk of western freshwater mussels according to the categories and criteria of the International Union for Conservation of Nature (IUCN) Red List. Percent change in occupied watersheds (by area) between historic and recent time periods was evaluated against IUCN-established thresholds. Additionally, we considered whether evidence of declines was also supported by reported observations of changes in abundance or occurrence in studied water bodies, watersheds, or regions. We also assessed the proportion of watersheds that have reduced species richness as compared with historic levels. We evaluated four western freshwater mussel taxonomic entities: three currently recognized species and one clade consisting of two currently recognized species. Of the four entities assessed, two are Vulnerable (Anodonta nuttalliana and Gonidea angulata), one is Near Threatened (Margaritifera falcata), and one is Least Concern (Anodonta oregonensis/kennerlyi clade). Freshwater mussel richness declined 35% across western watersheds by area, and among the most historically diverse watersheds, nearly half now support fewer species/clades. Future research and conservation efforts should prioritize identifying the proximate causes for these declines and preserving existing habitat and populations.
Viruses in the family
Rhabdoviridae
infect a variety of hosts, including vertebrates, invertebrates, plants and fungi, with important consequences for health and agriculture. This study describes two newly discovered viruses of freshwater mussels from the United States.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.