Cryptic intercontinental dispersal, commercial retailers, and the genetic diversity of native and non-native cattails (Typha spp.) in North America

Abstract

Although cattails (Typha spp.) are important components of wetlands around the world, the three most widespread species (T. angustifolia, T. domingensis, T. latifolia) are becoming increasingly dominant. We used global phylogenetic and phylogeographic assessments to test the hypotheses that each species has experienced multiple introductions of divergent lineages into North America and that commercial retailers are aiding long-distance dispersal. Our analyses identified T. angustifolia as a paraphyletic species with a highly divergent lineage. We found evidence for at least one introduced T. angustifolia lineage in wild populations and garden centres of North America. Although potentially complicated by incomplete lineage sorting, our data suggest dispersal of T. domingensis between Europe and Australia, and further investigation should assess a possible introduction of a non-native T. domingensis lineage into North America. T. latifolia has experienced bidirectional dispersal between North America and Europe, and a sample of T. latifolia purchased in a Canadian garden centre was an Asian lineage. Interspecific hybridization and novel intraspecific admixture have been repeatedly implicated in biological invasions, including invasions by the hybrid cattail Typha × glauca, and future work should focus on the potential contributions of non-native lineages to regional patterns of invasion by Typha spp. in North America.