Crawl-out behaviour in response to predation cues in an aquatic gastropod: insights from artificial selection

Local adaptation to predation often occurs in populations experiencing stable predator regimes. Under such conditions, prey species may respond by fine-tuning their behavioural defences towards a local optimum, although it is often difficult to ascertain whether such local adaptation is due to selection on fixed traits, developmental plasticity that is dependent on relatively long term exposure to environmental cues or phenotypic plasticity that can respond rapidly to a changing environment. Here we investigate whether anti-predator behaviour in two populations of the freshwater gastropod Lymnaea stagnalis responded to artificial selection. Previous work had shown that populations of this species showed a higher level of innate avoidance behaviour (crawling above the water line) in the presence of predatory fish compared with sites lacking this predation threat. By selectively breeding from high and low response selection lines, we demonstrated that this crawl-out behaviour responds rapidly to artificial selection: high response selection lines showed a significant increase and low response selection lines a significant decrease in avoidance compared with non-selected control lines. This suggests that the crawl out response in this species is heritable, and that there is potential for a response to selection in natural populations, which may produce the divergence in the plasticity of crawl out behaviour found between gastropod populations experiencing high and low predation intensity.