A groundbreaking study by Geoffrey Trussell and James Corbett at Northeastern University, published in Science Advances, outlines one of the first examples of rapid evolution in a marine system in response to an invasive predator and warming oceans.
The paper, titled “Evolution in changing seas: the loss of plasticity under predator invasion and warming oceans,” uses field experiments in the Gulf of Maine conducted 20 years apart, to document rapid changes in shell thickness of the intertidal snail L. obtusata and the potential processes driving these changes Shell thickness is a key defense for these animals against shell crushing predators – such as the invasive predatory green crab Carcinus maenas. The study found that the snail’s rapid evolution coincided with a geographic shift in the green crabs’ range expansion. The initial study conducted in the late 1990s showed that the presence of cues signaling green crab predation risk induced snails to produce thicker shells via plasticity. Now, however, it appears that natural selection has been eroding this plasticity, leading to genetic fixation of variation in shell thickness in response to more established green crab populations. The study highlights the importance of understanding the basis of adaptation in order to facilitate more robust predictions of the ecological and evolutionary impacts of ongoing environmental change.
Research was conducted by the Trussell Lab at Northeastern University’s Coastal Sustainability Institute and Department of Marine and Environmental Sciences. This study builds on decades of work investigating ecology and evolution of marine communities, particularly the role of species interactions in shaping communities.
Full Abstract from ‘Evolution in changing seas’:
The impact of invasive predators during the early stages of invasion is often variable in space and time. Such variation is expected to initially favor plasticity in prey defenses, but fixed defenses as invaders become established. Coincident with the range expansion of an invasive predatory crab in the Gulf of Maine, we document rapid changes in shell thickness—a key defense against shell crushing predators—of an intertidal snail. Field experiments, conducted 20 years apart, revealed that temporal shifts in shell thickness were driven by the evolution of increased trait means and erosion of thickness plasticity. The virtual elimination of the trade-off in tissue mass that often accompanies thicker shells is consistent with the evolution of fixed defenses under increasingly certain predation risk.
For further information, please contact:
Dr. Geoffrey Trussell
Coastal Sustainability Institute/ Department of Marine and Environmental Sciences
Northeastern University
