Data from: Is Hydroides dianthus (Verrill, 1873) really a Mediterranean native? Increased sampling in the eastern United States reveals enhanced genetic diversity

<p>The introduction of non-indigenous species (NIS) is a significant threat to marine biodiversity, facilitated by vectors such as shipping and aquaculture. <em>Hydroides dianthus,</em> a tubicolous polychaete worm, is known for its biofouling capabilities, impacting both shipping and aquaculture. Traditionally, the east coast of the United States has been considered the native range of <em>H. dianthus</em>. However, previous studies have suggested the Mediterranean region as the species' true native range based on higher genetic diversity. This study aims to re-evaluate the genetic diversity patterns of <em>H. dianthus</em> on the east coast of the United States by expanding the cytochrome c oxidase I (COI) dataset currently available for the species. Samples were collected from various locations on the east coast and analyzed using DNA barcoding. The results revealed a three-fold increase in haplotype diversity on the east coast compared to previous findings. A hierarchical AMOVA indicated significant genetic structuring between the Mediterranean and U.S. populations (ϕST = 0.51, P &lt; 0.05). Despite a higher genetic diversity in the Mediterranean, this study highlights the variability of genetic diversity estimates and the challenges in using such metrics to delineate native ranges. Factors such as multiple introductions, genetic drift, and sampling bias can significantly alter genetic variability within populations. The findings suggest that the east coast's genetic diversity is likely underestimated and that more comprehensive data, including high-throughput genomic analyses and ecological studies, are needed to determine the native range of <em>H. dianthus</em> conclusively. This study underscores the complexity of using genetic data to trace the biogeography and invasion pathways of marine species.</p>