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Ultraconserved yet informative for species delimitation: UCEs resolve long-standing systematic enigma in Central European bees
  • Morgan Gueuning,
  • Juerg Frey,
  • Christophe Praz
Morgan Gueuning
Universite de Neuchatel Institut de Biologie
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Juerg Frey
Agroscope Standort Wadenswil
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Christophe Praz
Universite de Neuchatel Institut de Biologie
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Abstract

Accurate and testable species delimitation hypotheses are essential for measuring, surveying and managing biodiversity. Today, taxonomists often rely on mitochondrial DNA barcoding to complement morphological species delimitations. Although COI barcoding has largely proven successful in assisting identifications for most animal taxa, there are nevertheless numerous cases where mitochondrial barcodes do not necessarily reflect the species history. For instance, what is regarded as one single species can be associated with two distinct DNA barcodes, which can point either to cryptic diversity or to deep within-species mitochondrial divergences with no reproductive isolation. In contrast, two or more species can share barcodes, for instance due to mitochondrial introgression. These intrinsic limitations of mitochondrial DNA barcoding can only be addressed with nuclear genomic markers, which are expensive, labour intensive, poorly repeatable, and often require high-quality DNA. To overcome these limitations, we examined the use of ultraconserved nuclear genetic elements (UCEs) as a quick and robust genomic approach to address such problematic cases of species delimitation. This genomic method was assessed using six different bee species complexes suspected to harbour cryptic diversity, mitochondrial introgression, or mitochondrial paraphyly. The sequencing of UCEs recovered between 686 and 1860 homologous nuclear loci and provided explicit species delimitation hypotheses in all investigated species complexes. These results provide strong evidence for the suitability of UCEs as a fast method for species delimitation even in recently diverged lineages. Furthermore, this study provided the first conclusive evidence for both mitochondrial introgression among distinct species, and mitochondrial paraphyly within a single bee species.

Peer review status:ACCEPTED

12 Mar 2020Submitted to Molecular Ecology
12 Mar 2020Submission Checks Completed
12 Mar 2020Assigned to Editor
31 Mar 2020Reviewer(s) Assigned
04 May 2020Review(s) Completed, Editorial Evaluation Pending
08 Jul 2020Editorial Decision: Revise Minor
21 Aug 2020Review(s) Completed, Editorial Evaluation Pending
21 Aug 20201st Revision Received
24 Aug 2020Editorial Decision: Accept