Relationships among arctic and non-arctic haplotypes of the moss species Scorpidium cossonii and Scorpidium scorpioides (Calliergonaceae)

Relationships among Scorpidium cossonii and Scorpidium scorpioides haplotypes from most of the species' distribution areas were analyzed based on ITS and rpl16. The haplotype networks were produced by TCS and were rooted by neighbor joining (ITS, recombination present) or maximum parsimony analysis. The haplotype closest to the root of the ITS network and some poorly represented haplotypes close to this have S. cossonii morphology and are arctic to subarctic, suggesting a northern origin of the complex. Additionally, two major lineages evolved from the root haplotype; one with S. cossonii morphology samples and one with all S. scorpioides morphology ones. The basal haplotypes in these major lineages include numerous temperate zone representatives, suggesting that adaptations for relatively warmer environments are present. Among haplotype groups that evolved later, one group in each major lineage is absent from America. rpl16 provides a scenario similar to that revealed by ITS for S. cossonii (no variation in S. scorpioides). Fossil and molecular evidence suggest that ancestral populations of S. cossonii evolved at least almost 4 Myr bp.