Polyploidy, phylogeography and Pleistocene refugia of the rockfern Asplenium ceterach: evidence from chloroplast DNA

Abstract

Chloroplast DNA sequences were obtained from 331 Asplenium ceterach plants representing 143 populations from throughout the range of the complex in Europe, plus outlying sites in North Africa and the near East. We identified nine distinct haplotypes from a 900 bp fragment of trnL-trnF gene. Tetraploid populations were encountered throughout Europe and further afield, whereas diploid populations were scarcer and predominated in the Pannonian-Balkan region. Hexaploids were encountered only in southern Mediterranean populations. Four haplotypes were found among diploid populations of the Pannonian-Balkans indicating that this region formed a northern Pleistocene refugium. A separate polyploid complex centred on Greece, comprises diploid, tetraploid and hexaploid populations with two endemic haplotypes and suggests long-term persistence of populations in the southern Mediterranean. Three chloroplast DNA (cpDNA) haplotypes were common among tetraploids in Spain and Italy, with diversity reducing northwards suggesting expansion from the south after the Pleistocene. Our cpDNA and ploidy data indicate at least six independent origins of polyploids.

Species Occurrence, Hybridization and Speciation in Postglacial East and South Asia

“…The high frequency of hybridization has been explained by ferns' relative lack of pre-zygotic reproductive isolation mechanisms. Many hybrid species are sexual and cross with other species, especially Asplenium species (Trewick et al, 2002;Van den heede et al, 2003;Shepherd et al, 2008). However, as we discussed above, apogamy is common in ferns and is maintained in absolute reproductive isolation.…”

A plastid phylogeny and character evolution of the Old World fern genus Pyrrosia (Polypodiaceae) with the description of a new genus: Hovenkampia (Polypodiaceae)

“…The rps4 gene and rps4-trnS intergenic spacer were amplified with primers TRNS (Souza-Chies et al, 1997) and an unnamed primer derived from Li and Lu (2006). The trnL intron and trnL-F intergenic spacer were amplified together using the primers FERN1 (Trewick et al, 2002) and F (Taberlet et al, 1991). All PCR conditions followed Zhang et al (2001).…”

First insights into the evolutionary history of the <I>Davallia repens</I> complex

“…In this study, some polyploid genotypes might have adapted to a cooler habitat and thus were able to disperse northward (in the northern hemisphere) or southward (in the southern hemisphere). The apogamous reproductive mode further enhances the chance of successful colonization of new habitats for these genotypes through the long distance dispersal of single spores (Schneller et al 1998, Page 2002, Trewick et al 2002, Pangua et al 2003, De Groot et al 2012.…”