Variable induced defenses of Mytilus edulis in response to two invasive crab predators with different invasion histories.
Freeman, Aaren*,1, 1 University of New Hampshire, Durham, NH
ABSTRACT- Inducible defenses, such as shell thickening in the blue mussel (Mytilus edulis), can alter the nature of species interactions. Recent work has shown that mussels can distinguish between predators having different attack strategies with appropriate defensive phenotypes. However, the evolution of these responses to novel, invasive predators has been largely ignored. Comparisons of mussel populations having different historical contact with invasive predators may provide insight into the evolution of inducible defenses. The European green crab (Carcinus maenas) and the Japanese shore crab (Hemigrapsus sanguineus) have differing ranges and histories of invasion on the Atlantic Coast of North America. This study compared the inducible defenses of two populations of M. edulis in response to waterborne cues from these invasive predators. These populations were a northern population that has currently never experienced predation by H. sanguineus and a southern population that has experienced predation from both crabs. M. edulis from northern populations raised with waterborne cues from C. maenas developed significantly thicker shells than mussels raised with either H. sanguineus or controls from the same population. In contrast, M. edulis from southern populations responded to both H. sanguineus and C. maenas with a similar degree of shell thickening. These results suggest that inducible defenses can arise in relatively few generations and can be very predator specific.
Key words: invasive species, Mytilus edulis, phenotypic plasticity, predator-prey
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