Genetic variation in clonal traits of Trifolium repens and species interactions

Plants exhibit a great variety of types of clonal growth. Moderate variation in clonal traits often exists even within species. The consequences of these variations for species interaction are of great interests to ecologists. In this paper, I address the small-leaved (phalanx) to large-leaved (guerrilla) variation in white clover ( Trifolium repens ), and discuss its consequences for species and genotype coexistence. I also address the clonal and sexual resource allocation variants within the large-leaved type. Small-leaved and large-leaved genotypes differ in various aspects of clonal growth. The large-leaved genotype displays greater phenotypic plasticity but is less physiologically integrated than the small-leaved genotype. We examined the consequences in a grazed sward, where white clover and zoysia grass coexist. In this sward, white clover is patchily distributed. We first tested the hypothesis that the large-leaved genotype is more advantageous in growth than the small-leaved genotype. Results from both common garden and competition experiments supported the hypothesis. Second, we tested the hypothesis that within large-leaved plants, the clonal subtype (which invests more resources to stolons but less in flower heads than the sexual one) is more advantageous than the sexual one because it is more competitive. This hypothesis was rejected. Both subtypes coexisted in the sward. This is probably because the sexual subtype is superior for interpatch migration than the clonal one. Both subtypes differ in advantages they offer for between-patch and within-patch processes, which promotes their coexistence. Finally, field monitoring of the behavior of a large-leaved clone is described. This monitoring was conducted in a moderately grazed sward, where microenvironmental heterogeneity is extremely high in time and space.