RT Journal Article SR Electronic T1 The Identification of Source and Vector of a Prolific Marine Invader JF bioRxiv FD Cold Spring Harbor Laboratory SP 083972 DO 10.1101/083972 A1 Stacy A. Krueger-Hadfield A1 Nicole M. Kollars A1 Allan E. Strand A1 James E. Byers A1 Sarah J. Shainker A1 Ryuta Terada A1 Thomas W. Greig A1 Mareike Hammann A1 David C. Murray A1 Florian Weinberger A1 Erik E. Sotka YR 2016 UL http://biorxiv.org/content/early/2016/10/27/083972.abstract AB The source and vector of an introduced species inform its ecological and evolutionary history and may guide management that seeks to prevent future introductions. Surprisingly, few studies have successfully used genetic tools to independently inform the specific source and pathway of biological invasions. The ecological history of many introduced species, including their origins and vectors, is often based on suppositions or educated guesses. Here, we used mitochondrial and microsatellite genotyping to trace the invasion of the Asian seaweed Gracilaria vermiculophylla (Rhodophyta) along the three coastlines of the Northern Hemisphere to which it has been introduced: the western coast of North America, eastern coast of the United States and the coasts of Europe and northwest Africa. Analyzing 37 native and 53 introduced sites, we identified the Pacific coastline of northeastern Japan as the ultimate source of the Northern Hemisphere invasion. Coincidentally, most exports of the oyster Crassostrea gigas historically originated from this region and both species often grow in close proximity. Based on genetic signatures, each of the three coastlines likely received thalli directly from Japan, as well as material from another introduced coastline (i.e., a secondary invasion). Our ability to document a source region, which was enabled by a robust sampling of locations and loci that previous studies lacked, reflected strong phylogeographic structure along native coastlines. We suggest Gracilaria vermiculophylla is an important representative example of many species likely exported out of Japan by the oyster trade and its genetic signatures that may be a hallmark of oyster introduction legacies.