Tournebize R. auteur aut IRD Manel S. auteur aut IRD Vigouroux Yves auteur aut IRD Munoz F. auteur aut IRD Kochko Alexandre de auteur aut IRD Poncet Valérie auteur aut IRD text journalArticle eng text/pdf reformatted digital access Past climate fluctuations shaped the population dynamics of organisms in space and time, and have impacted their present intra-specific genetic structure. Demo-genetic modelling allows inferring the way past demographic and migration dynamics have determined this structure. Amborella trichopoda is an emblematic relict plant endemic to New Caledonia, widely distributed in the understory of non-ultramafic rainforests. We assessed the influence of the last glacial climates on the demographic history and the paleo-distribution of 12 Amborella populations covering the whole current distribution. We performed coalescent genetic modelling of these dynamics, based on both whole-genome resequencing and microsatellite genotyping data. We found that the two main genetic groups of Amborella were shaped by the divergence of two ancestral populations during the last glacial maximum. From 12,800 years BP, the South ancestral population has expanded 6.3-fold while the size of the North population has remained stable. Recent asymmetric gene flow between the groups further contributed to the phylogeographical pattern. Spatially explicit coalescent modelling allowed us to estimate the location of ancestral populations with good accuracy (< 22 km) and provided indications regarding the mid-elevation pathways that facilitated postglacial expansion. specialized NOUVELLE CALEDONIE 076 082 020 021 064 12 8 e0183412 [18 p.] 2017 1932-6203 https://www.documentation.ird.fr/hor/fdi:010070945 10.1371/journal.pone.0183412 1932-6203 [F B010070945] https://www.documentation.ird.fr/hor/fdi:010070945 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-09/010070945.pdf IRD - Base Horizon / Pleins textes 2017-10-03 2023-07-11 fdi:010070945 fre