Genetic and demographic aspects of Varronia curassavica Jacq. in a heterogeneous coastal ecosystem

Abstract

The restinga is a threatened Brazilian ecosystem and a highly heterogeneous environment. This work aimed to evaluate demographic and genetic aspects of Varronia curassavica and whether environmental heterogeneity can infl uence the studied population parameters. Three annual evaluations were carried out in an area of restinga in Florianópolis-SC, Brazil. Demographic data were analyzed using descriptive statistics, and the spatial distribution pattern was calculated by Ripley's K-function and correlated with environmental characteristics. To characterize diversity and genetic structure, eight microsatellite markers were used. This work demonstrated that variations in the distribution of individuals and genotypes can be related to specifi c environments. Dry lowlands were environments favorable to population development, and fl ooded lowland and mobile dunes were unfavorable. The fi xation indices were distinct between environments, evidencing a tendency toward preferential crosses in favor of heterozygotes. We found absence of spatial genetic structure, indicating that genotypes are randomly distributed and that gene fl ow may be related to such genetic factors as the presence of autoincompatibility mechanisms. This diversity of environments contributed to the aggregate distribution and is relevant for the maintenance of demographic and genetic processes of the species in restingas, and this aspect should be considered for in situ conservation.