The postglacial history of Euphrasia micrantha in Scotland: evidence from genome skimming

The flora of northern Europe has been shaped by a complex history of glaciation, where species have recolonised from different refugia and spread via contrasting migration routes. Our understanding of plant phylogeography in northern Europe has been limited by the resolution of genetic markers that cannot detect subtle population structure arising from close or cryptic refugia. Here, we employ genome skimming to recover complete plastid genomes and partial nuclear ribosomal arrays in the widespread plant species Euphrasia micrantha. We focus on populations from Scotland, where cryptic and complex patterns of recent recolonisation may prove hard to resolve. Genome skimming from 145 individuals revealed a species specific plastid DNA lineage in Scotland and England, while two other genetic clusters were highly intermixed with co-occurring taxa. Within the distinct plastid DNA lineage we recover subtle genetic divergence corresponding to West-East differentiation. These findings suggest E...., , , # The postglacial history of *Euphrasia micrantha* in Scotland: evidence from genome skimming

Dataset DOI: [10.5061/dryad.b8gtht7pm](10.5061/dryad.b8gtht7pm)

## Description of the data and file structure

This dataset includes complete plastid genomes and partial nuclear ribosomal DNA (nrDNA) sequences obtained through genome skimming of 145 *Euphrasia* individuals. Leaf tissue was collected from field populations across Scotland and England, and total genomic DNA was extracted and sequenced using Illumina short-read technology. Reads were quality-filtered and organellar genomes were assembled bioinformatically to extract complete plastid sequences and nrDNA arrays. The dataset includes aligned sequence files, associated sample metadata (species ID, geographic origin), and phylogenetic trees inferred using maximum likelihood methods. These data were used to explore population structure and postglacial history in *Euphrasia micrantha*, with broader relevance for phylogeographic inferen...,