Despite forest fragmentation, river connectivity maintains gene flow and diversity in Guadua trinii, a woody bamboo of the Atlantic Forest in Argentina

Abstract

Factors such as life history traits, environmental conditions, and landscape characteristics influence genetic diversity and structure. Rivers act as corridors that aid dispersal and gene flow among riparian species, such as the bamboo Guadua trinii, commonly known as the “tacuara brava” which grows along riversides and gallery forests in South America. We examined how the topography, river connectivity,environmental variables, and habitat suitability influence functional connectivity of G. trinii in the Atlantic Forest of Misiones, Argentina. We also assessed populations both inside and outside the confines of Iguazú National Park using nine microsatellite markers. Our findings revealed high genetic diversity (HE = 0.50) and low genetic structure (FST = 0.068),indicating substantial gene flow among populations. Genetic differentiation was primarily influenced by river connectivity, followed by precipitation during the wet-test month (BIO13) and elevation; geographic distance did not have a significant effect on genetic differentiation. Within the study area, niche modeling showed the highest suitability of G. trinii, suggesting high connectivity between populations. Levels of genetic diversity and population differentiation did not significantly differ between protected and unprotectedareas. These results underscore the pivotal role of river connectivity in preserving genetic diversity, despite ongoing forest degradation and landscape modification.