Journal Article

The base number of ‘loxoscaphoid’ <i>Asplenium</i> species and its implication for cytoevolution in Aspleniaceae

Elke Bellefroid, S. Khadijah Rambe, Olivier Leroux and Ronald L. L. Viane

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 106, issue 1, pages 157-171
Published in print July 2010 | ISSN: 0305-7364
Published online May 2010 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcq095
The base number of ‘loxoscaphoid’ Asplenium species and its implication for cytoevolution in Aspleniaceae

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  • Evolutionary Biology
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Background and Aims

‘Loxoscaphoid’ Asplenium species are morphologically a remarkably distinct group of Aspleniaceae. Except for two preliminary chromosome counts of Asplenium theciferum, the cytology of this group of species has, however, been largely unstudied.

Methods

Chromosome counts were obtained by acetocarmine squash preparations of one mitotic cell and several meiotic cells. Relative DNA content of gametophytic and sporophytic cells was determined by flow cytometry. The phylogenetic placement of A. loxoscaphoides, A. rutifolium s.l. and A. theciferum s.l. was investigated through an analysis of rbcL sequences.

Key Results

The dysploid base number is reported to be x = 35 in Asplenium centrafricanum, A. loxoscaphoides, A. sertularioides and A. theciferum. Analysis of rbcL sequences confirms that ‘loxoscaphoids’ nest robustly within Asplenium. Several high ploidy levels exceeding the tetraploid level were found in A. theciferum s.l. and A. rutifolium s.l. All taxa proved to be sexual.

Conclusions

Four base numbers are known at present for Aspleniaceae: x = 39, 38, 36 and 35. The dysploid base number x = 35 found in the ‘loxoscaphoid’ Asplenium spp. sheds a novel light on the cytoevolution of the whole family. We postulate a recurrent descending dysploid evolution within Aspleniaceae, leading to speciation at the (sub)generic and species/group level.

Keywords: Dysploidy; cytology; cytoevolution; Aspleniaceae; Asplenium centrafricanum; Asplenium loxoscaphoides; Asplenium rutifolium; Asplenium sertularioides; Asplenium theciferum; polyploidization; chromosome base number; aneuploidy

Journal Article.  9382 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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