ABSTRACT
PREMISE OF THE STUDY How cosmopolitan, spore dispersed species diverge and new species arise is unknown. One potentially important mechanism of sympatric speciation in flowering plants is polyploidy, often in combination with hybridization. The main aim of this study is to provide a broad perspective of the possible genetic and genome size diversity inside the moss C. purpureus s.l in the Mediterranean area, an important hotspot of biodiversity.
METHODS Mosses of the genus Ceratodon from mountainous areas and lowlands of the Mediterranean region and some western and central European countries were studied. To reconstruct the phylogenetic relationships five nuclear introns and a chloroplast locus were sequenced. Genome size was estimated using flow cytometry technology with propidium iodide fluorochrome. Sex was determined by a molecular marker.
KEY RESULTS Two well differentiated clades with high supports were resolved by the sequence analyses, discriminating two homogeneous groups of specimens: widespread C. purpureus and a local group from southern Spain mountains; those that present a mixed genome are interpreted as recombinants, according to a coalescent simulation analysis. The two groups also significantly differ in genome size; moreover, a third group, probably polyploid, has been found. No males were found in samples with the new genotype.
CONCLUSIONS A new local species evolved despite significant spore-mediated long-distance gene flow in Ceratodon and retains its genetic distinctiveness despite some level of hybridization with sympatric widespread C. purpureus. The reproductive isolation may be associated with the decrease of males.