Phylogenetic and Biogeographic Relationships among North American and Hawaiian Pteridium aquilinum (L.) Kuhn (Dennstaedtiaceae) Based on Chloroplastrps4andrps4-trnSIntergenic Spacer Sequences

Nucleotide sequences encompassing the chloroplast rps4 gene and the rps4-trnS intergenic spacer were obtained for several specimens representing North American and Hawaiian members of Pteridium aquilinum (ingroup), as well as Pteridium esculentum (outgroup). Nucleotide divergence between ingroup bracken taxa was low. The rps4-trnS intergenic spacer contained indels distinguishing P. aquilinum and P. esculentum. Phylogenetic analyses and a haplotype network recognized two major groups within Northern American bracken that are divided along both genetic and geographic lines. The Hawaiian var. decompositum and the western North American var. pubescens share a similar chloroplast genome and grouped together. Despite morphology and geographical distribution, sequences for var. feei and eastern North American var. latiusculum were very similar and grouped together. Sequence data could not distinguish eastern North American var. latiusculum and the southeastern North American var. pseudocaudatum. Haplotype and biogeographic analyses suggest a most recent common eastern North American ancestor for the ingroup.