Abstract

The freshwater gastropod Lymnaea stagnalis was used as a model organism to investigate the mechanisms employed by prey species to fine-tune anti-predator behaviour to match their environment. Lymnaea stagnalis was found to exhibit both genetic adaptation of innate responses and also induced responses to predator cues. Snails were also capable of responding to predation cues via associative learning dependent on recent experience. Constitutive responses were found to differ between populations depending on the predator regime that the population experienced in the wild. Artificial selection produced in only two generations a difference in the magnitude of response between high and low response selected lines equal to those seen between field populations in two generations. At the same time these selected lines maintained phenotypic plasticity and responded to exposure to predator cues during development. This developmental plasticity led to an increased response to predation cues in the low selected line equivilent to that in the high response selection line; a lack of induced change in behaviour in the high response selection line suggested a physiological limitation on the maximum anti-predator response. The response in the low selection lines indicates that plasticity in anti-predator behaviour could allow individuals with low innate responses to compensate with high levels of induced response. Finally, L. stagnalis was able to utilise alarm cues from prey guild members (i.e. other freshwater gastropods) to assess predation risk, a response that was dependent on the phylogenetic relationship between L. stagnalis and the species producing the alarm cue. However, this response was dependent on whether the species was found sympatrically ( cohabiting the same water body) with L. stagnalis. Together, the rapid microevolution of constitutive responses in L. stagnalis, its ability to show induced responses and associative learning indicates that this species may be able to respond rapidly to a novel predation environment, and therefore allow colonistion of new habitats or identification of novel predators.

Document Type

Thesis

Publication Date

2007

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