A global phylogeny of the dryland moss genus 𝙎𝙮𝙣𝙩𝙧𝙞𝙘𝙝𝙞𝙖

Abstract

Though its approximately 90 named species occur in varied habitats worldwide, the moss genus Syntrichia is known for its dryland specialists, demonstrating a remarkable amount of variation in life history and ecology. The goal of this study was to understand the higher-level relationships of the genus. We addressed the following questions (1) Is Syntrichia, as currently defined, a monophyletic group? (2) What are the closest relatives of Syntrichia? (3) What are the major clades within this group? and (4) What can we tell aout its biogeographic history? Our research group is undertaking phylogenetic analyses of Syntrichia at several scales; here we report results based on data from a genome skimming approach. We sequenced 608 samples chosen to represent the full biogeographic, morphological, and taxonomic variation in the group. From de novo genome assemblies for each sample and from mining NCBI Genbank, we selected a small set of loci: chloroplast rbcl, rps4, and trnL-trnF; mitochondrial nad5; nuclear rDNA (including ITS regions), and 9 single-copy nuclear loci. Phylogenetic analysis proceeded in two steps using an ML approach (1) analyzing each locus separately to compare gene tree topologies; (2) concatenating all loci into a single matrix to infer the backbone phylogeny. Results include a well-supported Syntrichia clade and the discovery of a diverse, primarily Northern Hemisphere clade that includes the S. ruralis complex and S. caninervis complex and may represent a recent and extensie radiation in ecology and morphology. We also find evidence of a Southern Hemisphere origin with multiple northward transitions.

Jenna Ekwealor

Biodiversity Genomics Postdoctoral Researcher

I am a Biodiversity Genomics Postdoctoral Fellow studying evolutionary eco-physiology of stress tolerance in plants with the Smithsonian Institution Data Science Lab.