Karyotypic diversity and cryptic speciation: Have we vastly underestimated moss species diversity?

Resumen

Karyotypic diversity is critical to catalyzing change in the evolution of all plants. By resulting in meiotic incompatibilityamong sets of homologous chromosomes, polyploidy and aneuploidy may facilitate reproductive isolation and thepotential for speciation. Across plants, karyotypic variants in the form of allopolyploids receive greater taxonomicattention relative to autopolyploids and aneuploids. In particular, the prevalence and significance of autopolyploidyand aneuploidy in bryophytes is little understood. Using Fritsch’s 1991 compendium of bryophyte karyotypes withaugmentation from karyological studies published since, we have quantified the prevalence of karyotypic variantsamong ~1500 extant morphological species of mosses. We assessed the phylogenetic distribution of karyologicaldata, the frequency of autopolyploidy and aneuploidy, and the methodological correlates with karyotypic diversity.At least two ploidy levels were recorded from 17% of species potentially increasing current taxonomic diversityof mosses to over 15,000 species. We find that for a given species, the number of unique karyotypes recorded iscorrelated with the number of populations sampled. The evidence suggests that cytological diversity likely underliesyet undescribed species diversity in mosses, and that intensive karyological sampling is a needed tool for its discovery