Abstract
Abstract Carex section Ceratocystis (Cyperaceae) is a group of recently evolved plant species, in which hybridization is frequent, introgression is documented, taxonomy is complex, and morphological boundaries are vague. Within this section, a unified taxonomic treatment of the Carex jemtlandica–Carex lepidocarpa species complex does not exist, and Norway may currently be the sole country accepting species rank for both. Carex jemtlandica is mainly confined to Fennoscandia and is thus a Fennoscandian conservation responsibility. This motivated us to test the principal hypothesis that both C. jemtlandica and C. lepidocarpa represent evolutionary significant units, and that both deserve their current recognition at species level. We investigated their evolutionary distinctiveness in Norway, using restriction site‐associated DNA sequencing and ecological niche modeling. Our genomic results reveal two genetic clusters, largely corresponding to C. jemtlandica and C. lepidocarpa that also remain distinct in sympatry, despite clear indications of ongoing hybridization and introgression. The ecological niche modeling suggests that they occupy different environmental niches. Jointly, our results clearly show that C. jemtlandica and C. lepidocarpa represent separately evolving entities that should qualify recognition as evolutionary significant units. Given the high level of introgression compared to other hybridizing species pairs in Carex we recommend treating C. jemtlandica as a subspecies of C. lepidocarpa.
Highlights
Species is the most common unit used in biological studies and ecological researches, as well as in nature management and biodiversity assessments (Coates et al, 2018)
As all three methods produced highly concordant results, in the following, we only present results from the principal component analyses (PCA) analyses based on allele frequencies
4 Discussion In Scandinavia, C. jemtlandica and C. lepidocarpa have been recognized as different taxa for close to a century
Summary
Species is the most common unit used in biological studies and ecological researches, as well as in nature management and biodiversity assessments (Coates et al, 2018). Evolutionary significant units (ESUs) are evolutionary lineages (often intraspecific) that are considered distinct for purposes of conservation (see Fraser & Bernatchez, 2001 and references therein). We follow the unified framework of defining such conservation units (i.e., ESUs), as defined by Fraser & Bernatchez (2001), implying restricted interlineage gene flow. Such lineages represent independent evolutionary trajectories that, due to the highly restricted gene flow, will have limited or no impact on the evolution, genetic variance, and demography of other such lineages
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