Fine-scale spatial genetic structure, neighbourhood size and gene dispersal in clonal plants: exploring the best possible estimates

Abstract

Gene movement in plants is determined by seed and pollen flow and its limitation results in spatial structuring of genetic variation, affecting potential levels of inbreeding within populations. In clonal plants, clonal propagation may also play an important role in spatial genetic structure (SGS). Characterization of SGS usually is done by analysing several spatial scales with large sample sizes to ensure a reliable measure. Several sampling strategies are available, but most are not suitable for clonal plants. Here, two sampling strategies were used to characterize within-population SGS structure and gene dispersal in a natural population of the clonal species Aechmea nudicaulis (Bromeliaceae) and the results between them were compared. The first was based on exhaustive sampling in a rectangular closed area, and the second was a stratified design along a linear transect. Different intensities and patterns of SGS were detected for each design and the linear design revealed stronger SGS over a wider range. The significant SGS revealed a restricted dispersal and comparisons of sexual versus vegetative components of gene dispersal suggest that clonal spread can be at least as important as sexual reproduction. Thus, the results suggest that for clonal plants the best strategy is the combination of both sampling schemes since each one unveils important aspects of spatial structure of the population.