CONICET | Buscador de Institutos y Recursos Humanos

? Background and Aims The Mediterranean-type forest of central Chile is considered a ?biodiversity hotspot?and a relic of a wider ancient distribution produced by past climatic oscillations. Nothofagus macrocarpa, commonlyknown as ?roble de Santiago?, is a threatened palaeoendemic of this forest, poorly represented in the protectedarea system. This tree has been repeatedly misidentified as the sister species N. obliqua, which has affectedits recognition and protection. Only a few populations of N. macrocarpa remain within a matrix of intensive landuse that has been affected by recent forest fires. We tested the hypothesis that current populations of N. macrocarpaare a relic state of a previously widespread range, with the aim of contributing to its identification, its biogeographicalhistory and the design of conservation measures using genetic information.? Methods We analysed remnant N. macrocarpa forests using nuclear (nDNA) and chloroplast DNA (cpDNA)sequences, conducted phylogenetic and phylogeographical analyses to reconstruct its biogeographical history, andassessed microsatellites [simple sequence repeats (SSRs)] to determine contemporary patters of diversity withinand among all remnant populations. We also examined the degree of past, current and potential future isolation ofN. macrocarpa populations using ecological niche models (ENMs).? Key Results The species N. macrocarpa was confirmed by nDNA sequences, as previously suggested bychromosomal analysis. Small isolated populations of N. macrocarpa exhibited moderate to high genetic diversityaccording to SSRs. cpDNA analysis revealed a marked past latitudinal geographical structure, whereas analysisof SSRs did not find such current structure. ENM analyses revealed local expansion?contraction of the N. macrocarparange during warmer periods, particularly in the northern and central ranges where basal-most cpDNAhaplotypes were detected, and recent expansion to the south of the distribution.? Conclusions Genetic patterns confirm that N. macrocarpa is a distinct species and suggest a marked latitudinalrelic structure in at least two evolutionarily significant units, despite contemporary among-population gene flow.This information must be considered when choosing individuals (seeds and/or propagules) for restoration purposes,to avoid the admixture of divergent genetic stocks.