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Reticulate phylogenetic patterns in diploid European Diphasiastrum (Lycopodiaceae).
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Department of Evolution, Genomics and Systematics.
(English)Manuscript (Other academic)
Abstract [en]

In Central Europe, three species belonging to Diphasiastrum are considered to be of homoploid hybrid origin. Diphasiastrum issleri is suggested to have originated from a cross between D. alpinum and D. complanatum, D. oellgaardii from D. alpinum and D. tristachyum, and D. zeilleri from D. complanatum and D. tristachyum. Variation at three nuclear regions and two chloroplast microsatellites verify the presence of all three putative parental combinations in Europe. Data obtained with Feulgen DNA image densitometry confirms that all specimens displaying such pattern are diploid. Also, two of three parental combinations have probably arisen repeatedly, implied by the occurrence of chloroplast haplotypes associated with different parents. The presented dataset cannot be used as argument for the existence of independent evolutionary entities hybrid origin. This is nonetheless an important first step in order to address the influence of reticulate evolutionary events in European Diphasiastrum

Keyword [en]
Keywords – Diphasiastrum, homoploid hybridization, Lycopodiaceae, Lycopodium, low copy nuclear genes, phylogenies, Feulgen DNA image densitometry
URN: urn:nbn:se:uu:diva-99578OAI: oai:DiVA.org:uu-99578DiVA: diva2:208221
Available from: 2009-03-16 Created: 2009-03-16 Last updated: 2010-01-14
In thesis
1. Reticulate Evolution in Diphasiastrum (Lycopodiaceae)
Open this publication in new window or tab >>Reticulate Evolution in Diphasiastrum (Lycopodiaceae)
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis relationships and the occurrence of reticulate evolutionary events in the club moss genus Diphasiastrum are investigated. Diphasiastrum is initially established as a monophyletic group within Lycopodiaceae using non recombinant chloroplast sequence data. Support is obtained for eight distinct parental lineages in Diphasiastrum, and relationships among the putative parent taxa in the hypothesized hybrid complexes; D. alpinum, D. complanatum, D. digitatum, D. multispicatum, D. sitchense, D. tristachyum and D. veitchii are presented.

Feulgen DNA image densitometry data and sequence data obtained from three nuclear regions, RPB2, LEAFY and LAMB4, were used to infer the origins of three different taxa confirmed to be allopolyploid; D. zanclophyllum from South Africa, D. wightianum from Malaysia and an undescribed taxon from China. The two Asian polyploids have originated from two different hybrid combinations, D. multispicatum x D. veitchii and D. tristachyum x D. veitchii. Diphasiastrum zanclophyllum originates from a cross between D. digitatum and an unidentified diploid taxon.

The occurrence of three homoploid hybrid combinations commonly recognized in Europe, D. alpinum x D. complanatum, D. alpinum x D. tristachyum and D. complanatum x D. tristachyum, are verified using the same three nuclear regions. Two of the three hybrid combinations are also shown to have originated from reciprocal crosses. Admixture analyses performed on an extended, dataset similarly identified predominately F1 hybrids and backcrosses. The observations and common recognition of hybrid species in the included populations are hence most likely due to frequent observations of neohybrids in hybrid zones. Reticulate patterns are, however, prominent in the presented dataset. Hence future studies addressing evolutionary and ecological questions in Diphasiastrum should emphasize the impact of gene flow between parent lineages rather than speciation as the result of hybridization.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 35 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 623
admixture analysis, Bayesian clustering, Diphasiastrum, Feulgen DNA image densitometry, homoploid hybridization, Lycopodiaceae, phylogenetic analysis, polyploidy, reticulate evolution
National Category
Biological Systematics
Research subject
Systematic Botany
urn:nbn:se:uu:diva-99584 (URN)978-91-554-7470-6 (ISBN)
Public defence
2009-04-29, Lindahlsalen, Norbyvägen 18, Uppsala University, 10:00 (English)
Available from: 2009-04-08 Created: 2009-03-16 Last updated: 2009-09-14Bibliographically approved

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Aagaard, Sunniva M.D.
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