Dissertation Research: Embryonic learning in stickleback: An evolutionary perspective

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The threespine stickleback (Gasterosteus aculeatus) is a widely-distributed species, occupying marine and freshwater ecosystems throughout the northern hemisphere. Widely distributed species are exposed to variable environmental conditions across their ranges, including variation in local predation. Learning to use sensory cues from the surrounding environment can greatly enhance predator avoidance, and can be an evolutionary adaptation to variation in predation. Embryonic and juvenile stickleback are at risk from a variety of predators, and therefore could benefit from use of environmental signals to learn and avoid local predators. Olfactory cues, such as odors released in a predator's waste, provide reliable information about a predator's diet and could be readily used by stickleback embryos and fry to learn predators. Examination of the post-hatching response of stickleback conditioned to predator odors as embryos versus unconditioned individuals demonstrated that under laboratory condition embryos do learn. This learning has a significant effect on post-hatching response to predator odors, as well as affecting subsequent learning opportunities. The aim of this study is to address whether the embryonic learning demonstrated in the laboratory is relevant in nature. The results of this research have important conservation implications, as learning is likely to play a critical role in allowing prey to recognize novel threats. Novel predators (typically sport fish) are regularly introduced to lakes containing stickleback and this poses an elevated risk to predator-naïve stickleback. This project has already involved several undergraduate research assistants, and will provide opportunities for additional graduate (Masters and Doctoral) and undergraduate students to gain experience in the laboratory and field, helping them develop their own research projects.