Resolving natural ranges and marine invasions in a globally distributed octocoral (genusCarijoa)

The first published report of the snowflake coral in Hawai‘i comes from Pearl Harbor in 1972; subsequent identification as the Caribbean octocoralCarijoa riiseiled to the general conclusion that it was introduced to Hawai‘i from a Caribbean source. In an attempt to confirm the source of the Hawaiian population, we used mitochondrial (mtDNA) and nuclear (nDNA) sequence data to compare Hawaiian populations with samples ofCarijoa(N = 244) collected worldwide. In addition, cumulative vessel traffic patterns from 1940–1979 were compiled for the Pacific Ocean to determine maritime connectivity to and from Hawai‘i during the assumed time of introduction.Carijoasampled from throughout Hawai‘i (N = 94) share none of the Caribbean mtDNA haplotypes and only a single nDNA allele (0 of 28 and 1 of 27, respectively), indicating that the Hawaiian populations derive from Indo-Pacific rather than Caribbean-Atlantic origins. Furthermore, both mtDNA and nDNA show significant isolation-by-distance patterns overall and among the Pacific and Hawaiian sampling regions. These data indicate thatCarijoais native to the Indo-Pacific. Published reports of geographically wide-ranging invasions ofCarijoathroughout the Pacific appear unfounded because our global sampling shows higher diversity in mtDNA (He= 0.87; π = 0.0023) and nDNA (D= 0.91; π = 0.042) throughout the Pacific relative to the Caribbean-Atlantic, indicating long evolutionary presence ofCarijoain the region. Our data clearly refute a Caribbean origin forCarijoain the Hawaiian Archipelago, and indicate that the genusCarijoais native to the Pacific and in need of further taxonomic evaluation.