Genotyping‐by‐sequencing resolves relationships in Polygonaceae tribe Eriogoneae

Abstract

The resolution of cryptic diversity is essential for understanding the evolutionary diversification of lineages and establishing conservation priorities. We examine relationships in Eriogoneae (Polygonaceae), a diverse lineage in western North America. We ask whether Eriogonum umbellatum, a morphologically and ecologically diverse species, is monophyletic and whether its varieties represent evolutionary lineages. We use genotyping‐by‐sequencing to assemble a SNP dataset for 51 species in the genera Chorizanthe, Eriogonum and Sidotheca. We report a hierarchical phylogenetic analysis using maximum likelihood to estimate the evolutionary history of Eriogoneae. We illustrate admixture components for 21 populations of E. umbellatum, representing four varieties, and test for lineage structure using TreeMix. We identify strongly supported clades within Eriogoneae. Many relationships in the Eucycla + Oregonium and Latifolia clades are supported, while most relationships within the Eriogonum subg. Oligogonum clade and a clade with most Chorizanthe remain unresolved. Eriogonum congdonii resolves within the main E. umbellatum clade, while populations of three varieties of E. umbellatum are closely related to E. ursinum and are associated with serpentine soils. ADmixture and TreeMix analyses suggest E. umbellatum varieties represent evolutionary lineages. These results from SNP data are largely consistent with previous phylogenetic studies of Eriogoneae based on sequence variation. Structure within Oligogonum suggests consistent environmental association and radiation after initial colonization of serpentine. Morphology is unreliable for the infraspecific taxonomy of E. umbellatum. Additional molecular studies are needed to resolve the evolutionary relationships and ecological diversification within this species, in Oligogonum, and in Eriogoneae.

Phylogenomics of the North American Desert RadiationLinanthus(Polemoniaceae) Reveals Mixed Trait Lability and No Single Geographic Mode of Speciation

“…Additionally, most studies have only used a handful of loci, largely resulting in poorly resolved phylogenies (e.g., Spencer and Porter 1997; Moore and Jansen 2006; Evans et al 2009; Porter et al 2010; Cacho et al 2014; Walden et al 2014; Azani et al 2019; Vasile et al 2020). More recently, a limited number of studies have used genomic approaches and more extensive taxon sampling shedding light on species-level relationships, patterns of within-species genetic variation, and potential drivers of diversification (Simpson et al 2017; Mabry and Simpson 2018; Lichter-Marck et al 2020; Pearman et al 2021; Rose et al 2021; Singhal et al 2021). Given that deserts are young hotspots of biodiversity, well-sampled groups are needed to assess the monophyly of lineages, elucidate species relationships, and untangle complex evolutionary patterns, typical of recent radiations.…”