Landscape configuration of an Amazonian island-like ecosystem drives population structure and genetic diversity of a habitat-specialist bird

Abstract

ContextAmazonian white-sand ecosystems (campinas) are open vegetation patches which form a natural island-like system in a matrix of tropical rainforest. Due to their clear distinction from the surrounding matrix, the spatial characteristics of campina patches may affect the genetic diversity and composition of their specialized organisms such as the small and endemic passerine Elaenia ruficeps.ObjectivesHere, we estimate the relative contribution of the current extension, configuration and geographical context of campina patches to the patterns of genetic diversity and population structure of E. ruficeps.MethodsWe sampled individuals of E. ruficeps from three landscapes in Central Amazonia with contrasting campina spatial distribution, from landscapes with large and connected patches to landscapes with small and isolated patches. We estimate population structure, genetic diversity, and contemporary and historical migration within and among the three landscapes and used landscape metrics as predictor variables. Furthermore, we estimate genetic isolation by distance and resistance among individuals sampled within landscapes.ResultsWe identified three genetically distinct populations with asymmetrical gene flow among landscapes and a decreasing migration rate with distance. Within each landscape, we found low genetic differentiation without genetic isolation by distance nor by resistance. In contrast, we found differentiation and spatial correlation between landscapes.ConclusionsOur results uncover population dynamics of E. ruficeps through time. Together with previous studies, this suggests that both regional context and landscape structure shape the connectivity among populations of campina specialist birds, and that Amazonian landscapes, together with their associated biota, have responded to recent climatic changes.

Fine scale patterns of genetic structure in three species of forest birds reveal no population structure and dynamic history within an Amazonian area of endemism

“…This approach allows an understanding of past responses to, and possibly future consequences of land use changes in Amazonia, including the consequences of habitat loss and fragmentation for species distributions and genetic structure (Rull, 2011). Disentangling the contribution of current and historical factors in explaining the distribution of genetic diversity is challenging and can only be achieved with a detailed knowledge of current environmental variables and re ned sampling schemes, conditions that are still rare in Amazonia (but see Capurucho et al, 2013;Ricklefs, 2012Ricklefs, , 2011Ricklefs, , 2006Riddle et al, 2008;Ritter et al, 2020;Tuomisto and Ruokolainen, 1997;Wiens and Donoghue, 2004).…”