A Century of Evolution in Spartina anglica

This chapter describes the origin, variation, and spread of the salt marsh grass Spartina anglica, and presents new material relating to its ecology and evolution. Using electrophoretically detectable variation, the strong circumstantial evidence is confirmed that S. anglica originated by chromosome doubling of the sterile hybrid between the Old World species Spartina maritima and the North American Spartina alterniflora. The extensive analysis of isoenzyme and seed protein phenotypes indicates that S. anglica is lacking in genetic variation. S. anglica is among temperate grasses––a C4 species. The species interaction with other species discusses the effects of S. anglica invasion on aerial and benthic invertebrates and on overwintering wading birds––Calidris alpine. Soil conditions, grazing and temperature are important factors affecting the competitive interaction. The consequences of the genetic bottleneck that occurred during the speciation process and the relative youth of S. anglica in evolutionary terms are emphasized by comparing the species with P. maritima. The greater variation, population differentiation and niche breadth of the species are evident. The changes which occur with global warming and rising sea levels and the affect of the species' evolution are also reviewed.