Intra-specific phylogeny of the native Patagonian grass Festuca pallescens

VERÓNICA GUIDALEVICH; MARÍA MARTA AZPILICUETA; ALDANA LÓPEZ; PAULA MARCHELLI

VIRTUAL

Simposio; II Virtual Meeting of Systematics, Biogeography, and Evolution: The Research of Biodiversity and the Diversity of Researchers; 2021

Drylands constitute the largest terrestrial biomes, highly sensitive to climate change and desertification, and known for their environmental heterogeneity. Widely distributed species are usually adapted to these heterogeneous environments characterized by climatic gradients which promote the expression of phenotypic variability and hybridization processes. The Patagonian native grass Festuca pallescens has a broad geographic distribution, occurring at highly diverse environments. Because of the broad phenotypic plasticity of this species, it can be hard to identify individuals on the field, particularly in extreme suboptimal habitats where repeated exposure to stressful conditions might enhance phenotypic variation or local adaptations. In addition, its ecological niche partly overlaps with other native grasses like Festuca argentina and F. gracillima, which also show morphological variability. Given the scarce information about the genetic variation of F. pallescens, and the possible hybridization and speciation processes at suboptimal conditions, the objective of this study was to reconstruct the phylogenetic relationships between populations of this forage grass. We included the sympatric species F. argentina and F. gracillima, as well as other fescues of the genus. A total of 20 populations along the distribution range of the species, which encompasses around 1.800 km of Patagonia, were sampled. Sequences from the ITS region, which allows phylogenetic reconstructions, were obtained and complemented with sequences of the chloroplast marker trnL-F. Sequences of species from other regions were retrieved from NCBI. The variation detected with these two markers allowed us to identify four variants with a clear geographic distribution. Edge populations were distinctly different from most of the populations noticing a northern, a north-eastern and two southern variants. From these, the north-eastern variant resembles F. argentina, and the southern variant was closely related with F. gracillima. These results constitute the first reconstruction of Patagonian fescues phylogeny and highlight the relevance of suboptimal regions for possible speciation and hybridization processes.