Worldwide Relationships in Pteridium

Recently published in American Journal of Botany. Seed‐free plants, including ferns and lycophytes, disperse via spores capable of traveling long distances in air currents. Does this mean that spore‐bearing species are genetically uniform across vast geographic distances? We tested this with one of the most widely distributed plant genera, Pteridium (bracken), a group of ferns with ecological and economic importance. Using over 2800 genetic loci, we compared plants from 100 locations worldwide, and found distinct genetic signatures at the continental scale. “Northern” and “Southern” hemispheres separate two diploid species, and two allotetraploids. We also found several hybrids, especially involving African genotypes, which may produce spores more readily than plants from other areas (due to a drier climate). The results illustrate that despite high dispersal ability and evidence of hybrids across continents, it is still possible to maintain distinct genetic identities on a continental scale.