Phylogeography of Asparagopsis Taxiformis (Bonnemaisoniales, Rhodophyta) in the Hawaiian Islands: Two Mtdna Markers Support Three Separate Introductions

Fifty-six samples of the gametophyte stage of Asparagopsis taxiformis, principally from the Main and Northwestern Hawaiian Islands, were obtained from field collections and archived herbarium material. Of these, 36 were successfully sequenced for the cox2-3 spacer region, and 42 for the COI gene. Parsimony analyses of both regions for the Hawaiian collections revealed relationships that were consistent with those previously published for global A. taxiformis samples, which also included a number from the Hawaiian Islands. The Main Hawaiian Islands are dominated by lineage 1, which is known from the Pacific coast of Central America and Hawai‘i. The Northwestern Hawaiian Islands, with one exception, contain a single widespread lineage (2) that is known from the Indo-Pacific, central Mediterranean and southern Portugal. A third lineage (4) is present in Hawai‘i only along a localized region of the south shore of O'ahu, but is widespread in tropical and subtropical waters outside of the Hawaiian Isla...