Intraspecific genetic variation of Batrachospermum gelatinosum (Batrachospermales, Rhodophyta) in eastern North America

Batrachospermum gelatinosum is a widespread taxon of freshwater red algae in eastern North America and elsewhere in the northern hemisphere. A total of 193 individuals from 16 stream segments in eastern North America ranging from Alabama in the south to Nova Scotia in the north, as well as three individuals from Europe were collected. Genetic variation among these individuals was assessed using the coxl barcoding region. Five haplotypes were revealed from the North American specimens with a single widespread haplotype representing most individuals. Of the other four haplotypes, three were collected exclusively in Alabama and one in Massachusetts. These Eve haplotypes only differed by 1-4 bp. There were two haplotypes detected in the European samples, which differed from the North American ones by 7-10 bp. This study substantiates previous research using the internal transcribed spacer region that B. gelatinosum is a genetically homogenous species that is highly plastic in its morphology. The data from this study implies a southern glacial refugium potentially in Alabama and subsequent dispersal of one haplotype to all northern areas. This pattern is similar to that seen in B. helminithosum and numerous other organisms. Currently, there are only genetic data on three freshwater red taxa, and information from other widespread Batrachospermales in eastern North America are needed to provide generalized phylogeographic patterns for this group and compare them with other aquatic organisms.