Landscape and climatic features drive genetic differentiation processes in a South American coastal plant

Abstract

Background: Historical and ecological processes shape patterns of genetic diversity in plant species. Colonization to new environments and geographical landscape features determine, amongst other factors, genetic diversity withinand diferentiation between-populations. We analyse the genetic diversity and population structure of Calibrachoa heterophylla to infer the infuence of abiotic landscape features on the level of gene fow in this coastal species of the South Atlantic Coastal Plain. Results: The C. heterophylla populations located on early-deposited coastal plain regions show higher genetic diversity than those closer to the sea. The genetic diferentiation follows a pattern of isolation-by-distance. Landscape features, such as water bodies and wind corridors, and geographical distances equally explain the observed genetic diferentiation, whereas the precipitation seasonality exhibits a strong signal for isolation-by-environment in marginal populations. The estimated levels of gene fow suggest that marginal populations had restricted immigration rates enhancing diferentiation. Conclusions: Topographical features related to coastal plain deposition history infuence population diferentiation in C. heterophylla. Gene fow is mainly restricted to nearby populations and facilitated by wind felds, albeit without any apparent infuence of large water bodies. Furthermore, diferential rainfall regimes in marginal populations seem to promote genetic diferentiation.