Genomic evidence of hybridization between two independent invasions of European green crab (Carcinus maenas) in the Northwest Atlantic

• Published in: Heredity 2017-09, Vol.119 (3), p.154-165
• Main Authors: Jeffery, N W, DiBacco, C, Wringe, B F, Stanley, R R E, Hamilton, L C, Ravindran, P N, Bradbury, I R
• Format: Article
• Language: English
• Subjects: Animals; Bayes Theorem; Bayesian analysis; Biological evolution; Brachyura - genetics; Clustering; Crabs; Crustaceans; Cytochrome-c oxidase; Demographics; Deoxyribonucleic acid; DNA; DNA sequencing; DNA, Mitochondrial - genetics; Ecological monitoring; Evolution; Genetic Markers; Genetics, Population; Hybridization; Hybridization, Genetic; Hybrids; Indigenous species; Introduced Species; Invasions; Invasive species; Microsatellite Repeats; Mitochondrial DNA; New Jersey; Newfoundland and Labrador; Nonnative species; Nucleotide sequence; Original; Oxidase; Polymorphism, Single Nucleotide; Populations; Sequence Analysis, DNA; Shellfish
• ISSN: 0018-067X; 1365-2540
• DOI: 10.1038/hdy.2017.22

Invasive species have been associated with significant negative impacts in their introduced range often outcompeting native species, yet the long-term evolutionary dynamics of biological invasions are not well understood. Hybridization, either among waves of invasion or between native and introduced populations, could alter the ecological and evolutionary impacts of invasions yet has rarely been studied in marine invasive species. The European green crab (Carcinus maenas) invaded eastern North America twice from northern and southern locations in its native range. Here we examine the frequency of hybridization among these two distinct invasions at locations from New Jersey, USA to Newfoundland, Canada using restriction-site-associated DNA sequencing (RAD-seq), microsatellite loci and cytochrome c oxidase subunit I mitochondrial DNA (mtDNA) sequences. We used Bayesian clustering and hybrid assignment analyses to investigate hybridization between the northern and southern populations. Of the samples analyzed, six locations contained at least one hybrid individual, while two locations were characterized by extensive hybridization, with 95% of individuals collected from Placentia Bay, Newfoundland being hybrids (mostly F ) and 90% of individuals from Kejimkujik, Nova Scotia being classified as hybrids, mostly backcrosses to the northern ecotype. The presence of both F hybrids and backcrossed individuals suggests that these hybrids are viable and introgression is occurring between invasions. Our results provide insight into the demographic and evolutionary consequences of hybridization between independent invasions, and will inform the management of green crabs in eastern North America.