Are species-pairs diverging lineages? A nine-locus analysis uncovers speciation among species-pairs of the Lobaria meridionalis-group (Ascomycota).

In spite of considerable effort to verify the theory of species-pairs, uncertainty still exists about the relationship between sexually or vegetatively reproducing populations of morphologically indistinguishable, sympatric lichen species. The current paper studies putative species-pairs within the Asian Lobaria meridionalis-group, using a nine-locus and time calibrated species-tree approach. Analyses demonstrate that pairs of sexually or vegetatively reproducing lineages split into highly supported monophyletic clades-confirming molecularly the species-pair concept for the L. meridionalis-group. In the broader context of evolution and speciation dynamics in lichenized fungi, this paper attempts to synthesize molecular findings from the last two decades to promote a more modern perception of the species-pair concept. Taxonomically, eight species were found to currently conform to the L. meridionalis-group, which differentiated during the Pliocene and Pleistocene. The coincidence of paleoclimatic events with estimated dates of divergence support a bioclimatic hypothesis for the evolution of species in the L. meridionalis-group, which also explains their current eco-geographic distribution patterns. Greater recognition for species with a long and independent evolutionary history, which merit high conservation priority, will be especially critical for preserving geographically restricted endemics from Southeast Asia, where habitat loss is driving rapid declines.