Induced Behavioral and Morphological Defenses of Marine Mollusks in Response to Invasive and Native Crabs Lecture
Stony Brook Univ., Southampton,
Evolution has afforded many organisms the capacity to recognize predation threats and respond behaviorally and/or morphologically. For marine mollusks, responses to predators can result in reduced foraging on lower trophic levels and/or increased shell thickness. Mollusks often rely on chemical cues to identify predation threats, however, biological invaders may circumvent these coevolved recognition systems, allowing invaders to remain unrecognized by native communities. A better understanding of the ecological and evolutionary impacts of biological invasions should consider chemical recognition and induced responses in native community members. Through several studies, I have explored how intertidal whelks and mussels respond (behaviorally and morphologically) to invasive and native crabs. The invasive crabs I have used include, Carcinus maenas (native to Europe and invasive in North America, Australia, South Africa and South America) and Hemigrapsus sanguineus (native to Asia and invasive in Europe and eastern North America). I have found that an induced morphological defense (shell thickening in mussels) diverges between populations invaded and uninvaded by Hemigrapsus; suggesting post-invasion, rapid evolution or acquired predator recognition. In contrast, whelks (Haustrum vinosum and Nucella lapillus) from both invaded and uninvaded populations recognized cues from Carcinus, and reduce foraging on mussels when the crab is present. Wave-exposure also influences some whelk populations’ ability to respond to Carcinus. I will discuss these studies with regard to rapid evolution, interactions between behavioral and morphological defenses and local variation in induced defenses.