Apomixis and reticulate evolution in the Asplenium monanthes fern complex |
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Authors: | Robert J Dyer Vincent Savolainen Harald Schneider |
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Institution: | 1.Department of Botany, Natural History Museum, London SW7 5BD, UK;2.Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK;3.Royal Botanic Gardens, Kew TW9 3DS, UK;4.State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, China |
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Abstract: | Background and AimsAsexual reproduction is a prominent evolutionary process within land plant lineages and especially in ferns. Up to 10 % of the approx. 10 000 fern species are assumed to be obligate asexuals. In the Asplenium monanthes species complex, previous studies identified two triploid, apomictic species. The purpose of this study was to elucidate the phylogenetic relationships in the A. monanthes complex and to investigate the occurrence and evolution of apomixis within this group.MethodsDNA sequences of three plastid markers and one nuclear single copy gene were used for phylogenetic analyses. Reproductive modes were assessed by examining gametophytic and sporophyte development, while polyploidy was inferred from spore measurements.Key ResultsAsplenium monanthes and A. resiliens are confirmed to be apomictic. Asplenium palmeri, A. hallbergii and specimens that are morphologically similar to A. heterochroum are also found to be apomictic. Apomixis is confined to two main clades of taxa related to A. monanthes and A. resiliens, respectively, and is associated with reticulate evolution. Two apomictic A. monanthes lineages, and two putative diploid sexual progenitor species are identified in the A. monanthes clade.ConclusionsMultiple origins of apomixis are inferred, in both alloploid and autoploid forms, within the A. resiliens and A. monanthes clades. |
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Keywords: | Apomixis Asplenium monanthes asexual reproduction apogamy diplospory reticulate evolution hybridization polyploidy |
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