Data from: Genetic identification of source and likely vector of a widespread marine invader

The identification of native sources and vectors of introduced
species informs its ecological and evolutionary history and may
guide policies that seek to prevent future introductions. Population
genetics represents a powerful set of tools to identify origins and
vectors, but can mislead when the native range is poorly sampled or few
molecular markers are used. Here, we traced the introduction
of the Asian seaweed Gracilaria vermiculophylla
(Rhodophyta) into estuaries in coastal western North
America, the eastern United States, Europe and
northwestern Africa by genotyping more than 2500 thalli from 37
native and 53 non-native sites at both mitochondrial and nuclear loci.
Overall, greater than 90% of introduced thalli have a genetic signature
similar to thalli sampled from the coastline of northeastern Japan,
strongly indicating this region served as the principal source of the
invasion. Notably, northeastern Japan exported the vast majority of the
oyster Crassostrea gigas during the 20th Century. The preponderance of
evidence suggests G. vermiculophylla may have been inadvertently
introduced with C. gigas shipments and that northeastern Japan is a common
source region for estuarine invaders. Each invaded Northern Hemisphere
coastline reflects a complex mix of direct introductions from Japan and
secondary introductions from each invaded coastlines. The spread of G.
vermiculophylla along each coastline was likely facilitated by
aquaculture, fishing and boating activities. Our ability to document a
source region was enabled by a robust sampling of locations and loci that
previous studies lacked and strong phylogeographic structure along native
coastlines.