Thermogeographic variation in body size of Carcinus maenas, the European green crab

Abstract

biogeographic differences in size (carapace width) exist for a recent invasion of the non-native European green crab, Carcinus maenas, along the west coast of North America. We assembled trapping and temperature data collected from 10 sites along the western North American coast over a 5-year period. We also conducted a literature review of C. maenas size across their native range. Our results indicate that adult body size shows negative correlation with environmental temperature in both the native and invaded ranges, conforming to the temperature-size rule for ectotherms. Given the short time since colonization and lack of evident genetic structure across the invasive range, it may be that phenotypic plasticity in response to environmental temperature is driving this relationship. Forces that shape the phenotypic trajectory of species may play an important role in both invasion dynamics and subsequent ecological impacts.

Morphological variability in populations of the fiddler crab Leptuca uruguayensis (Nobili, 1901) (Crustacea, Decapoda, Ocypodidae) from South America

“…This inverse correlation between size and temperature was also observed for Carcinus maenas (LINNAEUS, 1758) (KELLEY et al, 2015). The temperature can act regulating the growth rate through two distinct hypothesis: 1) the temperature can act as a selective agent, producing evolutionary changes (through genetic mutations) in the genes controlling growth rates and the size of adults (PARTRIDGE et al, 1994); 2) the variation in temperature during development can change the expression of genes that regulate growth, resulting in a phenotypically plastic response (NUNNEY; CHEUNG, 1997).…”

PopulationDynamics of Green Crabs (Carcinus maenas) -- A Review

“…Green crabs in nonindigenous populations tend to be larger than those in the native population [38,148,188] and males are generally larger than females. Moreover, the species appears to follow the temperature-size rule for ectotherms, whereby the largest individuals are found in the coldest parts of the range (see Table 3).…”

“…They spread only 125 km southward to Elkhorn Slough in the Monterey Bay area but over 1500 km northward in just 12 years, reaching Oregon in 1995-1996, British Columbia, Canada in 1998 and more recently Vancouver Island in 2005 and Gales Passage, mainland British Columbia by 2015 [15,22,[36][37][38]. This population contains the single haplotype found in the northwest Atlantic population south of Nova Scotia so is almost certainly a secondary introduction from that population to the northeastern Pacific coastline [11,30].…”

“…A similar trend of male biased ratios being more common in the higher latitude portion and female biased ratios being more common in the lower latitude portion of a range is seen in the northeastern Pacific nonindigenous population. At ten trapping sites between Barkley Sound, British Columbia, Canada and Elkhorn Slough, California, US, the sex ratios were biased toward males at the colder sites and became more female biased at the warmer sites [38] (See Table 1 for details).…”

“…The largest C. maenas on record to date is a 113 mm (converted from reported value of 104 mm) male from British Columbia [38]. Grosholz and Ruiz [15] suggest that crabs of size 110-115 mm CW may be attainable and, although not published, there is a report of a crab from British Columbia that measured 106 mm (presumably this is a notchto-notch measurement so would be 116 mm when converted) [37].…”