Climatic gradients model genetic diversity in widespread woody trees: The case of Nothofagus pumilio in the southern Andes

Abstract

Climatic gradients model genetic diversity in widespread woody trees: the case of the widely distributed Nothofagus in the southern Andes. Widespread forest species are well suited to be the subject of studies combining adaptive responses to distinct habitats. We studied the genetic diversity of the wideranging Nothofagus pumilio that inhabits highelevation and highlatitude forests, along different environmental gradients in Patagonia. The results of this study show a strong relationship between climate and the different environmental gradients; which in turn affect the genetic variation of N. pumilio. The most influential variables were related to summer precipitations and winter temperatures, where greater genetic diversity was associated to higher precipitations and milder temperatures. This demonstrates that the genetic diversity of this species is not randomly distributed in space, but it is structured according to complex climatic models. To understand how genetic adaptation and/or environmental aspects influence species' distribution ranges is crucial to evaluate their potential for long term survival. While some genotypes may become locally extinct under different climatic settings, others might be locally adapted to particular climatic conditions, which may allow them to endure such changes. Widespread taxa as N. pumilio has undergone past environmental changes, such as those that occurred during glacial periods, through adaptation and plasticity. We highlight the importance of conserving genetic diversity of populations, not only to ensure the longterm persistence, but also to mitigate the negative impacts of global climate change.