The population genetics of Festuca rubra on park grass

Abstract

An explanation for the ubiquity of sexual reproduction remains elusive although it is commonly suggested that sex and recombination facilitate a more rapid response to environmental change than clonal reproduction. If this suggestion is true then one would expect the frequency of sexual reproduction within populations to increase with rate of environmental change. The study described here investigates the potential correlation between mode of reproduction and rate of environmental change in red fescue, Festuca rubra, a clonal/sexual species of perennial grass. Populations are identified that have experienced contrasting histories of change over the past 138 years, and within which the ratios of clonally to sexually derived individuals have been determined. From these ratios the selection pressures on mode of reproduction in each of the Festuca rubra populations investigated are inferred. The unexpected discovery that Festuca rubra is represented by two sub-species at the main study site has also prompted investigations into the factors governing their relative frequencies and distributions. Since the sub-species represent different cytotypes within the red fescue aggregate, this has allowed for inferences to be made relating to their observed coexistence and the apparent overcoming of minority cytotype exclusion by the subspecies found at lower frequencies