Clonal integration in Fragaria chiloensis differs between populations: ramets from grassland are selfish.

In plants, only species with clonal growth are able to directly transfer resources between otherwise independent units of the same genetic individual. A simple conceptual model of plant performance as a function of internal resource supply and environmental resource availability suggests that resource sharing between ramets within clones is likely to be disadvantageous in uniform habitats and advantageous in patchy ones. It was therefore hypothesized that clones in populations from relatively uniform habitats will have been selected for low rates of resource sharing between ramets compared to clones in populations from patchier habitats. In coastal northern California, the clonal herb Fragaria chiloensis is common both in grasslands, where resources are relatively uniform, and on sand dunes, where resources are more patchy. It was predicted that clones from a grassland population of Fragaria would have "selfish" ramets with low rates of resource sharing compared to clones from an adjacent dune population. Ramets were subjected to contrasting light levels with and without connection between ramets. Patterns of biomass accumulation were consistent with the prediction. This appears to be the first report of genetically based variation in patterns of resource sharing in clonal plants. It supports the idea that these patterns are locally selected to increase plant performance in habitats with different patterns of resource availability.