Aveliina and her colleagues from the University of Oulu published a research paper that explores the patterns and distribution of freshwater plant species in Europe and North America, and whether similar laws apply to both continents. A study conducted by Janne Alahuhta, a researcher at the University of Oulu, found that species richness in freshwater plants is more related to today's climate patterns and less to historical climate. Surprisingly they found that the species richness of freshwater plants in North America and Europe has developed on somewhat different bases. It was found that while latitude is an important indicator of biodiversity for many more studied taxonomic groups, this is not true for all groups and regions, so generalizations should be made with caution.
Alahuhta, J., Antikainen, H., Hjort, J., Helm, A. & Heino, J., Current climate overrides historical effects on species richness and range size of freshwater plants in Europe and North America. Journal of Ecology. https://doi.org/10.1111/1365-2745.13356
Species richness and mean range size of freshwater plants in Europe and North America.