Phylogeography and population differentiation in the Psittacanthus calyculatus (Loranthaceae) mistletoe: a complex scenario of climate–volcanism interaction along the Trans‐Mexican Volcanic Belt

Abstract

AbstractAimThe formation of the Trans‐Mexican Volcanic Belt (TMVB) played an important role in driving inter‐ and intraspecific diversification at high elevations. However, Pleistocene climate changes and ecological factors might also contribute to plant genetic structuring along the volcanic belt. Here, we analysed phylogeographical patterns of the parrot‐mistletoe Psittacanthus calyculatus to determine the relative contribution of these different factors.LocationTrans‐Mexican Volcanic Belt.MethodsUsing nuclear and chloroplast DNA sequence data for 370 individuals, we investigate the genetic differentiation of 35 populations across the species range. We conducted phylogenetic, population and spatial genetic analyses of P. calyculatus sequences along with ecological niche modelling and Bayesian inference methods to gain insight into the structuring of genetic variation of these populations.ResultsOur analyses revealed population structure with three genetic groups corresponding to individuals from Oaxaca and those from the central‐eastern and western TMVB regions. A significant genetic signal of demographic expansion, an east‐to‐west expansion predicted by species distribution modelling, and approximate Bayesian computation analyses strongly supported a scenario of habitat isolation and invasion of TMVB by P. calyculatus during the late‐Pleistocene.Main conclusionsThe genetic differentiation of P. calyculatus may be explained by the combined effects of (1) geographical isolation linked to the effects of the glacial/interglacial cycles and environmental factors, driving genetic differentiation from congeners into more xeric vegetation and (2) the invasion of TMVB from east to west, suggesting a role for both colonization and glacial/interglacial cycles models.