Naturally fragmented and isolated distribution in subtropical grassland patches affects genetic diversity and structure at different spatial scales: The case of , an endemic shrub from Brazil.

PREMISE OF THE STUDY

The genetic structure of organisms results from the interactions between life history traits and the ecological and demographic characteristics of the landscape that shape the intra- and interpopulation genetic variation in space and time. In this study, we used a species restricted to islands of grassland vegetation in southern Brazil to investigate the effects of its naturally fragmented distribution on diversity and genetic structure patterns.

METHODS

Diversity and intra- and interpopulational genetic structure were analyzed using polymorphisms of eight nuclear microsatellite markers in 205 individuals of and Bayesian and multivariate methods.

KEY RESULTS

At the intrapopulation level, populations presented low genetic diversity and strong spatial genetic structure, indicating a greater spatial autocorrelation until ∼50-500 m. At the interpopulation level, genetic variation partitioned into two geographically structured genetic clusters. Gene flow through pollen was more efficient than gene flow by seeds.

CONCLUSIONS

Genetic structure was influenced locally by seed and pollen dispersal dynamics and regionally by fragmentation of the grassland landscape. This study highlights the importance of geological barriers, and potentially a role for genetic drift, in influencing diversification of species in subtropical grasslands of southern Brazil.