Genetic patterns across multiple introductions of the globally invasive crab genus Carcinus

Abstract

The European green crab Carcinus maenas is one of the world's most successful aquatic invaders, having established populations on every continent with temperate shores. Here we describe patterns of genetic diversity across both the native and introduced ranges of C. maenas and its sister species, C. aestuarii, including all known non-native populations. The global data set includes sequences from the mitochondrial cytochrome c oxidase subunit I gene, as well as multilocus genotype data from nine polymorphic nuclear microsatellite loci. Combined phylogeographic and population genetic analyses clarify the global colonization history of C. maenas, providing evidence of multiple invasions to Atlantic North America and South Africa, secondary invasions to the northeastern Pacific, Tasmania, and Argentina, and a strong likelihood of C. maenas x C. aestuarii hybrids in South Africa and Japan. Successful C. maenas invasions vary broadly in the degree to which they retain genetic diversity, although populations with the least variation typically derive from secondary invasions or from introductions that occurred more than 100 years ago.

RAD sequencing reveals genomewide divergence between independent invasions of the European green crab (Carcinus maenas) in the Northwest Atlantic

“…Previous studies have used COI sequence variation to study green crab population structure and to trace the invasion history (Darling, 2011; Darling et al., 2008, 2014; Roman, 2006). Overall, our SNP data were similar to COI in terms of resolving the current spatial structure of the invasions and suggests that patterns of divergence found in the mitochondria are widespread across the nuclear genome.…”

“…Our results indicate unusually high levels of genomewide differentiation among invasions consistent with observed differences in northern invasion success. We observed strong evidence for two genetically and geographically distinct populations of green crab spatially segregated in eastern North America corresponding to two independent invasions (Darling et al., 2008, 2014), which show clear latitudinal clines in RAD‐seq‐derived SNP allele frequency. As observed in other species (e.g., Atlantic salmon ( Salmo salar ), Freamo, O'Reilly, Berg, Lien, & Boulding, 2011; Moore et al., 2014; sea scallop ( Placopecten magellanicus ), Van Wyngaarden et al., 2017), our most divergent SNPs (i.e., outliers) explained more of the spatial variance in allele frequency than either background (neutral) SNPs or COI data.…”

“…For identification, the resulting sequence for each individual was then aligned to reference sequences, haplotypes H1–H6 and H8–H10 from Darling et al. (2008) (Genbank accession numbers FJ159008–FJ15016) using Vector NTI Advance v11 (Life Technologies).…”

“…2002 from a Scotian Shelf population (Blakeslee et al., 2010). Green crab population structure has been investigated previously using traditional genetic markers, including mitochondrial DNA (16S, Geller, Walton, Grosholz, & Ruiz, 1997; COI, Darling, Bagley, Roman, Tepolt, & Geller, 2008; Roman & Palumbi, 2004; Roman, 2006) and microsatellites (Darling, 2011; Darling et al., 2008, 2014; Pascoal et al., 2009; Tepolt, Bagley, Geller, & Blum 2006). In their native range, green crab show distinct broadscale structuring of island populations (i.e., Faeroe Islands and Iceland) and northern and southern European populations (Roman & Palumbi, 2004) using COI sequence data and fine‐scale (~450 km) structuring has been reported using microsatellite loci (Pascoal et al., 2009).…”

Modeling invasion risk for coastal marine species utilizing environmental and transport vector data

“…All five species have shipping related vectors (wet and dry ballast, hull fouling, and sea chests) as documented or potential transport mechanisms (McDermott, 1998;Carlton and Cohen, 2003;Tavares & Amouroux, 2003;Gust & Inglis, 2006;Roche & Torchin, 2007). Additional vectors, including seafood and aquaculture trade (e.g., R. harrisii transport from the eastern USA to the western USA) and natural dispersal (e.g., C. maenas on the USA West Coast and between Australia and Tasmania), are cited as responsible for secondary spread (Rodríguez & Suárez, 2001;Darling et al, 2008;Tepolt et al, 2009). While secondary spread is important for determining species distributions, this research is focused on predicting risk from initial introduction based on commercial shipping as a vector.…”