title: Lack of adult novel northern lineages of invasive green crabCarcinus maenasalong much of the northern US Atlantic coast.
abstract: Introduced over 200 yr ago to the east coast of North America,Carcinus maenasnow ranges from New York to Newfoundland. In the 1980s, a secondary invasion of European lineages, termed northern haplotypes, occurred in Nova Scotia. Young-of-the-year sampled in 2007 revealed that northern haplotypes were present in low frequencies at several northwestern Atlantic sites as far south as New York; a model predicted an increase in their range and frequency over time. We collected samples in 2013 and 2014 to determine the haplotypes of adult crabs from New York to Nova Scotia. Six haplotypes, encompassing previously identified northern and southern haplotypes, 1 novel southern haplotype, and 1 Scandinavian haplotype, were identified in 275 crabs sampled at 11 sites. Northern haplotypes were only found in Nova Scotia, Beals Island (Maine), and Mount Desert Island (Maine) at a frequency of 60, 8, and 24%, respectively; remaining sites were predominantly composed of a previously identified southern haplotype. Northern haplotypes are limited in adult crabs to Mount Desert Island and north, indicating that the southern haplotype is selectively favored at some point during their life history, recruitment of northern larvae is limited south of Mount Desert Island, or entire year-classes post-2007 were lost. Our results do not support the predictions of an increase in the range and frequency of northern haplotypes, at least among adults, and indicate that a more complete knowledge of factors affectingC. maenaslife stages is necessary to understand the current distribution of haplotypes.
authors.affiliation: Department of Biology, Bates College, Lewiston, ME 04240, USA; The Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04609, USA.
authors.forename: Larissa M
authors.initials: LM
authors.lastname: Williams
authors.affiliation: Department of Biology, Bates College, Lewiston, ME 04240, USA.
authors.forename: Camilla L
authors.initials: CL
authors.lastname: Nivison
authors.affiliation: Department of Biology, Bates College, Lewiston, ME 04240, USA; Akvaplan-niva, FRAM - High North Research Centre for Climate and the Environment, 9296 Tromsø, Norway.
authors.forename: William G
authors.initials: WG
authors.lastname: Ambrose
authors.affiliation: Department of Biology, Bates College, Lewiston, ME 04240, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Dobbin
authors.affiliation: Department of Biology, Bates College, Lewiston, ME 04240, USA.
authors.forename: William L
authors.initials: WL
authors.lastname: Locke
keywords: Carcinus maenas; Invasive species; Mitochondrial DNA; Population genetics; Range