Clonal integration as an evolutionary strategy for surviving disturbance: insights from the study of rhizomatous dune species.
Dong, Ming*,1, Yu, Fei-Hai1, He, Wei-Ming1, Liu, Hai-Dong1, Liu, Feng-Hong1, 1 Institute of Botany, Chinese Academy of Sciences, Beijing, China
ABSTRACT- Ramets of clonal plants may be physically connected to one another, allowing matter exchange among ramets (clonal integration). Today evidence has been increasingly accumulated for a positive effect of clonal integration on fitness and/or fitness-related traits, suggesting clonal integration, as an evolutionary strategy, helps buffer small-scale environmental heterogeneity, particularly that caused by local disturbance. Here we review evidences from studies of a number of rhizomatous plants, particularly those in semiarid sandy grasslands where water and nutrient supply is limited, grazing happens frequently and habitats are severely desertified/fragmented. Meanwhile, two case studies are emphasized. One is a field experiment in which ramet populations of rhizomatous dune species Bromus ircutensis and Psammochloa villosa were subjected to local foliage clipping and rhizome severing. The results suggest that clonal integration increases ramet populationís compensatory responses to grazing. In the other field experiment with rhizomatous dune species Hedysarum leave and P. villosa, the hypothesis was tested that in a highly disturbed environment, a species forming large clonal fragments possesses more extensive and/or intensive clonal integration gaining essential resources than that forming small ones. The results suggest that P. villosa is an extensive and intensive integrator, whereas H. leave is a restrictive and less intensive integrator, supporting the hypothesis.
Key words: clonal integration, evolutionary strategy, rhizomatous plants, semiarid sandy grassland
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