Diversity of Xanthoparmelia (Parmeliaceae) species in Mexican xerophytic scrub vegetation, evidenced by molecular, morphological and chemistry data

Alejandrina Barcenas-Peña,Felix Grewe,Steven D Leavitt,H Thorsten Lumbsch

doi:10.3989/ajbm.2564

Abstract

The genus Xanthoparmelia is the largest genus of lichen- forming fungi with about 800 species worldwide. Xanthoparmelia is also common in the deserts of central Mexico, but only a few molecular studies exist on its species’ diversity in this region. In this study, we sampled 38 Xanthoparmelia species from around the world including species from the xerophytic scrubs of central Mexico to assess the diversity using an integrative approach. Molecular phylogenetic analyses were performed using a combination of the ITS, mtSSU and nuLSU genetic markers. We evaluated our phylogenetic results in a context of traditional morphological and chemical characters. The combined evidence of molecular, morphological, and chemical data identified a total of 18 Xanthoparmelia species-level lineages occurring in central Mexico. However, numerous traditionally circumscribed species did not form monophyletic groups in the molecular phylogenetic reconstructions. This conflict indicates that taxonomy and species delimitation in the genus Xanthoparmelia requires revision and emphasizes the importance of molecular evidence for more robust species delimitations in this genus.

Highlights

The diversity of organisms is distributed unequally in the world
We focus on the xerophytic scrub, which is among the most widespread ecosystems in Mexico, covering about 40% of the country and harbouring high biodiversity
DNA sequences were generated for three markers using the polymerase chain reaction (PCR): the nuclear ribosomal internal transcribed spacer region (ITS), a region of the mitochondrial small subunit rDNA, and a region of the nuclear large subunit rDNA

Summary

INTRODUCTION

The diversity of organisms is distributed unequally in the world. Species distributions are influenced by a wide range of factors, including biogeographic history, topography, or climate (Fischer 1960; Brown 2001; Rozzi & al. 2008). We focus on the xerophytic scrub, which is among the most widespread ecosystems in Mexico, covering about 40% of the country and harbouring high biodiversity. This vegetation is adapted to face aridity and mainly consists of low trees, shrubs and succulent plants (Rzedowski 1978). The xerophytic scrub is an ecosystem that requires a deep molecular study of Xanthoparmelia species We studied the diversity of Xanthoparmelia species in xerophytic scrub vegetation of the central part of Mexico using morphology, secondary chemistry, and molecular sequence data to understand the phylogenetic diversity and relationship among the species

MATERIAL AND METHODS

Molecular methods

RESULTS AND DISCUSSION