Recent hybrid speciation at the origin of the narrow endemic

Grünig, Sandra; Fischer, Markus; Parisod, Christian (2021). Recent hybrid speciation at the origin of the narrow endemic. Annals of Botany, 127(1), pp. 21-31. Oxford University Press 10.1093/aob/mcaa145

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Background and aims: Hybridization is known to drive plant speciation through the establishment of homoploid or allopolyploid hybrid species. Here we investigate the origin of Pulmonaria helvetica, a narrow endemic species described across a restricted area of Switzerland that was entirely covered by ice during the last glacial maximum. This species presents an original number of chromosomes (2n = 24) and morphological traits suggestive of a hybrid origin.

Methods: We sequenced a plastid locus and 1077 double-digest restriction site associated DNA (ddRAD) loci in 67 individuals from across the distribution range of P. helvetica and candidate progenitor species growing in the same area. Assignment of genotypes to main genetic clusters within and among taxa using STRUCTURE tested whether P. helvetica represents a genetically differentiated lineage and addressed the hypothesis of its hybrid origin. Comparative ecological modelling further addressed possible niche differentiation among taxa.

Key results: P. helvetica was highlighted as a genetically homogeneous species distinct from co-occurring taxa. Consistent with a scenario of hybrid speciation, it presented clear evidence of balanced admixture between P. officinalis (2n = 16) and P. mollis s.l. (2n = 18, 22) that was also highlighted as maternal progenitor based on plastid sequences. Limited genetic structure within the maternal progenitor is consistent with an origin of P. helvetica through either homoploid hybridization with considerable karyotype changes or via complex scenarios of allopolyploidy involving a dysploid taxon of P. mollis s.l. Comparative niche modelling indicated non-significant ecological differences between P. helvetica and its progenitors, supporting intrinsic factors resulting from hybridization as main drivers of speciation.

Conclusions: Hybridization appears as a major process having promoted the postglacial origin of the narrow endemic P. helvetica, suggesting hybrid speciation as an effective process that rapidly produces new species under climate changes.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Plant Ecology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Ecological Genomics

UniBE Contributor:

Grünig, Sandra; Fischer, Markus and Parisod, Christian Gérard

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

0305-7364

Publisher:

Oxford University Press

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

12 Aug 2020 11:00

Last Modified:

05 Jan 2021 08:39

Publisher DOI:

10.1093/aob/mcaa145

PubMed ID:

32738145

Uncontrolled Keywords:

Pulmonaria.; ddRAD; dysploidy; ecological modelling; endemic species; homoploid hybridization; postglacial expansion; speciation

BORIS DOI:

10.7892/boris.145695

URI:

https://boris.unibe.ch/id/eprint/145695

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