Phylogeography and cryptic introduction of the ragworm Hediste diversicolor (Annelida, Nereididae) in the Northwest Atlantic

• Published in: Invertebrate Biology
• Main Authors: Einfeldt, Anthony L., Doucet, Jeremy R., Addison, Jason A.
• Other Authors: Natural Sciences and Engineering Research Council of Canada, New Brunswick Innovation Foundation, Canada Foundation for Innovation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2014
• Subjects: North Atlantic; Northeast Atlantic; Northwest Atlantic
• Online Access: http://dx.doi.org/10.1111/ivb.12060; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fivb.12060; https://onlinelibrary.wiley.com/doi/pdf/10.1111/ivb.12060

Abstract Many benthic marine invertebrates show striking range disjunctions across broad spatial scales. Without direct evidence for endemism or introduction, these species remain cryptogenic. The common ragworm Hediste diversicolor plays a pivotal role in sedimentary littoral ecosystems of the North Atlantic as an abundant prey item and ecosystem engineer, but exhibits a restricted dispersal capacity that may limit connectivity at both evolutionary and ecological time scales. In Europe, H. diversicolor is subdivided into cryptic taxa and genetic lineages whose distributions have been modified by recent invasions. Its origin in the northwest Atlantic has not been adequately addressed. To trace the age and origin of North American ragworm populations, we analyzed mt DNA sequence data ( COI ) from the Gulf of Maine and Bay of Fundy ( n =73 individuals) and compared our findings with published data from the northeast Atlantic. Our results together with previous data indicate that two species of the H. diversicolor complex have independently colonized the northwest Atlantic at least three different times, resulting in two distinct conspecific assemblages in the Bay of Fundy and Gulf of Maine (respectively) that are different from the species found in the Gulf of St. Lawrence. North American populations had significantly lower genetic diversity compared with populations in the northeast Atlantic, and based on patterns of shared identity, populations in the Bay of Fundy originated from the Baltic Sea and North Sea. Populations from the Gulf of Maine were phylogenetically distinct and most likely originated from unsampled European populations. Analyses of the North American populations revealed patterns of post‐colonization gene flow among populations within the Gulf of Maine and Bay of Fundy. However, we failed to detect shared haplotypes between the two regions, and this pattern of complete isolation corroborates a strong phylogeographic break observed in other species.