Analysis of changes in population structure over time in components of multi-species swards.

In multi-species swards, the genetic structure of populations of heterogeneous outbreeding species is likely to change over time, potentially affecting inter-species population dynamics. In this study, mixtures of outbreeding forage crops were established in swards, and periodically defoliated by cutting or grazing for two years. Changes in population structure varied from species to species. White clover showed significant genetic change over two years, while red clover did not. For perennial ryegrass, a sub group in the initial population exhibiting unique alleles was no longer present two years later. Key genes associated with stress tolerance and flowering time varied significantly with these changes in population structure.