New insights on the origin of the woody flora of the Chihuahuan Desert: The case of Lindleya.

Abstract

We reconstructed aspects of the evolutionary history of Lindleya, a shrubby element in the rose family, as a model for identifying the ancestral area of the biota of the Chihuahuan Desert and for understanding the effect that pre-Pleistocene or Pleistocene climate fluctuations had on the evolution of the plants of this desert. We conducted phylogenetic, biogeographic, and phylogeographic analyses based on one nuclear DNA and two plastid markers sequenced for 20 populations comprising 153 accessions and representing the species' entire distribution range. We carried out ecological niche modeling to forecast Lindleya's potential distribution under Current, Last Interglacial, and Last Glacial Maximum conditions. The ancestral area of Lindleya populations was probably in the central and southern parts of the Chihuahuan Desert. Levels of genetic and haplotype variation were the highest in the northernmost and southernmost areas and low levels of genetic variation in the central part. Extended Bayesian skyline plots including all populations identified a slight demographic expansion ∼1 Ma. The predicted potential distribution during the Last Glacial Maximum was very restricted. We suggest that pre-Pleistocene changes had an influence on the divergence of Lindleya populations. We also suggest that the ancestral area for Lindleya was the Chihuahuan Desert and that the uplift of the Trans-Mexican Volcanic Belt isolated the Tehuacán Valley populations. Genetic and demographic analyses as well as and ecological niche modeling indicate that populations of Lindleya experienced genetic bottlenecks and that they have expanded since the Last Glacial Maximum.