Evol Ecol Res 17: 565-581 (2016)     Full PDF if your library subscribes.

The relative roles of genes and rearing environment
on the spatial cognitive ability of two sympatric species of threespine stickleback

Jonatan Martinez^1,2*, Jason Keagy^1,2,3*, Benjamin Wurst^1,2, William Fetzner^4,5 and Janette W. Boughman^1,2,3

¹Department of Integrative Biology, Michigan State University, East Lansing, Michigan, USA,  ²BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan, USA,  ³Program in Ecology, Evolutionary Biology and Behavior, Michigan State University, East Lansing, Michigan, USA,  ⁴Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, USA and  ⁵Department of Psychology, University of North Carolina Wilmington, Wilmington, North Carolina, USA

Correspondence: J. Keagy, Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA. email: keagy@msu.edu

ABSTRACT

Background: Recently diverged populations provide a powerful model for studying trait evolution. Benthic sticklebacks primarily occupy vegetated areas of lakes, a spatially complex environment. Limnetic sticklebacks primarily occupy open water in lakes, a spatially simple environment. In a T-maze spatial learning assay, wild-caught benthic sticklebacks perform better than wild-caught limnetic sticklebacks. It is not known whether this difference has a genetic basis and is thus the result of evolution or is instead a plastic response to the contrasting environments.

Question: To what extent are differences in the spatial cognitive ability of benthic and limnetic sticklebacks influenced by genetic differences, rearing environment, or the interaction between the two?

Methods: Using wild-caught limnetic and benthic fish from Paxton and Priest Lakes, we made pure-species crosses in the lab. We reared the fertilized eggs in spatially simple or spatially complex lab environments. We used a previously validated T-maze spatial learning assay to quantify the ability of adult fish from each rearing environment to learn an association between a visual landmark and a reward location.

Results: Lab-reared benthic fish learned the spatial task faster and made fewer errors than lab-reared limnetic fish, which supports a genetic basis underlying species differences in spatial learning ability. However, we found no significant differences between fish raised in different artificial environments.

Keywords: cognitive evolution, common garden, genetic basis, phenotypic plasticity, spatial learning, threespine stickleback.

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