Molecular Evidence of Reticulate Evolution in the Peatmosses (Sphagnum), IncludingS. ehyalinum sp. nov.

Abstract

Abstract Phylogenetic analyses of nuclear and chloroplast DNA sequences resolve four major clades within the peatmosses, and these lineages correspond to sections that have traditionally been recognized based on morphology. The sectional placement of most species is unambiguous, but four taxa combine the nuclear sequences of one section with the chloroplast sequences of another. A hypothesis of past reticulate evolution is favored over lineage sorting to account for this incongruence, because single genome analyses (nuclear vs. chloroplast) indicate that the species are derived within their respective sections. Sphagnum mendocinum, from the Pacific coast of North America, has the nuclear DNA of section Subsecunda, but the chloroplast DNA of section Cuspidata. Sphagnum cuculliforme, from Ecuador, has the nuclear sequences of section Subsecunda, but the chloroplast sequences of section Sphagnum. Sphagnum falcatulum and S. ehyalinum, both from temperate Southern Hemisphere, have the nuclear sequences of sect...