Local-scale patterns of genetic variation in coexisting floating-leaved Nymphoides peltata and submerged Myriophyllum spicatum in Donghu Lake

Coexisting floating-leaved and submerged plants experience similar environmental changes but may evolve different patterns of genetic variation. To compare local-scale genetic variation, we collected samples of floating-leaved Nymphoides peltata and submerged Myriophyllum spicatum coexisting in a disturbed urban lake in China. At the subpopulation level, using microsatellites, M. spicatum had higher clonal diversity than N. peltata. M. spicatum had 28.4% multilocus genotypes (MLGs) shared between subpopulations, but N. peltata had only one MLG shared between two adjacent subpopulations. N. peltata displayed more genetic variation between subpopulations than within subpopulations, but the reverse was true for M. spicatum . Principal components and Bayesian cluster analyses showed that individuals from each subpopulation of N. peltata tended to have relatively close genetic relationships. For M. spicatum , individuals from each subpopulation were genetically scattered with those from other subpopulations. Our results imply that in unpredictable adverse environments M. spicatum may be less subjected to local-deme extinction than N. peltata because of genetically diverse clones at the subpopulation level. This characteristic means that following adverse events, M. spicatum may rapidly restore subpopulation distributions via re-colonization and intense gene flow among subpopulations.