Influence of Pleistocene climatic oscillations on the phylogeography and demographic history of endemic vulnerable trees (section Magnolia) of the Tropical Montane Cloud Forest in Mexico

Yessica Rico; M Ángel León-Tapia; Marisol Zurita-Solís; Flor Rodríguez-Gómez; Suria Gisela Vásquez-Morales

doi:10.7717/peerj.12181

Influence of Pleistocene climatic oscillations on the phylogeography and demographic history of endemic vulnerable trees (section Magnolia) of the Tropical Montane Cloud Forest in Mexico

PeerJ. 2021 Sep 28:9:e12181. doi: 10.7717/peerj.12181. eCollection 2021.

Authors

Yessica Rico^{1

2}, M Ángel León-Tapia³, Marisol Zurita-Solís¹, Flor Rodríguez-Gómez⁴, Suria Gisela Vásquez-Morales⁵

Affiliations

¹ Red de Diversidad Biológica del Occidente Mexicano, Instituto de Ecología A.C., Pátzcuaro, Michoacán, México.
² CONACYT, Ciudad de México, México.
³ Laboratorio de Sistemática Filogenética, Red de Biología Evolutiva, Instituto de Ecología A.C., Xalapa, Veracruz, Mexico.
⁴ Departamento de Ciencias Computacionales, División de Electrónica y Computación, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico.
⁵ Departamento de Biología, División de Ciencias Naturales y Exactas, Universidad de Guanajuato, Guanajuato, Guanajuato, México.

Abstract

The Tropical Montane Cloud Forest (TMCF) is a highly dynamic ecosystem that has undergone frequent spatial changes in response to the interglacial-glacial cycles of the Pleistocene. These climatic fluctuations between cold and warm cycles have led to species range shifts and contractions-expansions, resulting in complex patterns of genetic structure and lineage divergence in forest tree species. In this study, we sequenced four regions of the chloroplast DNA (trnT-trnL, trnK5-matk, rpl32-trnL, trnS-trnG) for 20 populations and 96 individuals to evaluate the phylogeography, historical demography, and paleodistributions of vulnerable endemic TMCF trees in Mexico: Magnolia pedrazae (north-region), M. schiedeana (central-region), and M. schiedeana population Oaxaca (south-region). Our data recovered 49 haplotypes that showed a significant phylogeographic structure in three regions: north, central, and south. Bayesian Phylogeographic and Ecological Clustering (BPEC) analysis also supported the divergence in three lineages and highlighted the role of environmental factors (temperature and precipitation) in genetic differentiation. Our historical demography analyses revealed demographic expansions predating the Last Interglacial (LIG, ~125,000 years ago), while Approximate Bayesian Computation (ABC) simulations equally supported two contrasting demographic scenarios. The BPEC and haplotype network analyses suggested that ancestral haplotypes were geographically found in central Veracruz. Our paleodistributions modeling showed evidence of range shifts and expansions-contractions from the LIG to the present, which suggested the complex evolutionary dynamics associated to the climatic oscillations of the Pleistocene. Habitat management of remnant forest fragments where large and genetically diverse populations occur in the three TMCF regions analyzed would be key for the conservation of these magnolia populations.

Keywords: Ecological niche modeling; Genetic divergence; Glacial refugia; Historical demography; Magnoliaceae; Paleodistributions; Phylogeography; Pleistocene.

Grants and funding

This work was supported by research funds to Yessica Rico by Instituto de Ecología A.C. Marisol A. Zurita-Solís received a CONACYT scholarship to pursue her master degree. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.