cognitive evolution

Cognition and Natural Selection

I took advantage of a recent species radiation (following the last Ice Age) of stickleback fish in British Columbia, Canada to study cognitive evolution in a comparative framework. Limnetic and benthic stickleback fish differ in their feeding habits, sociality, habitat complexity, body size, shape, antipredator defenses, mating traits, and dependence on vision vs. olfaction, suggesting differences in cognitive abilities and neuroanatomical structures might exist. Selection is strongly implicated when consistent differences between limnetic and benthic fish are demonstrated across lakes. I used two very different, but complementary approaches:

First, I conducted behavioral experiments in Jenny Boughman's lab at Michigan State University to assess specific cognitive abilities in each species. As one example, I quantified social information use, specifically the ability to use the feeding behavior of others to locate a food patch. This work involved undergrads Whitley Lehto, Ross Minter, Ashley Baird, and Sarah LoPresto and was published in Biology Letters. As another example, I and undergrad Jonatan Martinez quantified the relative role of genes and environment in producing species differences in spatial learning (with lots of help from undergrads Benjamin Wurst and William Fetzner). That work was published in Evolutionary Ecology Research.

Second, I collected neuroanatomical data on specific brain structures using magnetic resonance imaging (MRI). This work was a collaboration between myself and Jenny Boughman at Michigan State University and Victoria Braithwaite and Thomas Neuberger at Penn State University, with help from undergrad Katelyn Doolittle. That work was published in a Special Column in Current Zoology, “Ecology and Evolution along Environmental Gradients”.

Cognition and Sexual Selection

In my doctoral dissertation research at the University of Maryland (advised by Gerald Borgia), I tested the cognitive performance hypothesis that males with better cognitive performance have higher reproductive success. Male display and female mate choice are highly complex processes in many species of animals and likely requires the need for complex and high-functioning brains. By presenting male satin bowerbirds (Ptilonorhynchus violaceus) problem solving tests, I have been able to show that males who are better problem solvers have higher reproductive success. To develop these problem solving tests, I took advantage of male aversion to red objects on their bowers and created an obstacle to removing the offending red things.

I also found that individuals who were on average better at a variety of cognitive tasks, including problem solving ability, were sexually preferred. Measures which integrate information from a large variety of cognitve tasks were strongly correlated with male mating success; in fact these were some of the best predictors of mating success in this species. How do females choose these males with better cognitive ability? The answer to this question has turned out to be very complex, with individual display traits not being good indicators of cognitive ability. Rather, males who are able to most effectively produce the most complete and complex displays are more likely to have better overall cognitive ability.

Inspired by this work, a Master’s student at the University of Denver I helped advise (Ross Minter) found that male stickleback fish with better inhibitory control are preferred by females. Furthermore, male sticklebacks are better at inhibitory control than females, perhaps because of the increased demands of this cognitive ability in parenting, which males do alone, although these cognitive differences are largely explained by differences in neophobia.