Learning capabilities enhanced in harsh environments: a common garden approach

Abstract

Previous studies have suggested that the ability to inhabit harsh environments may be linked to advanced learning traits. However, it is not clear if individuals express such traits as a consequence of experiencing challenging environments or if these traits are inherited. To assess the influence of differential selection pressures on variation in aspects of cognition, we used a common garden approach to examine the response to novelty and problem-solving abilities of two populations of black-capped chickadees (Poecile atricapillus). These populations originated from the latitudinal extremes of the species's range, where we had previously demonstrated significant differences in memory and brain morphology in a multipopulation study. We found that birds from the harsh northern population, where selection for cognitive abilities is expected to be high, significantly outperformed conspecifics from the mild southern population. Our results imply differences in cognitive abilities that may be inherited, as individuals from both populations were raised in and had experienced identical environmental conditions from 10 days of age. Although our data suggest an effect independent of experience, we cannot rule out maternal effects or experiences within the nest prior to day 10 with our design. Nevertheless, our results support the idea that environmental severity may be an important factor in shaping certain aspects of cognition.

Variation in memory and the hippocampus across populations from different climates: a common garden approach

“…In addition to differences in spatial memory and caching, we have also found striking differences in cognitive-based behaviours such as problem solving and the response to neophobia [23]. In those cases, the individuals from the Alaskan population showed significantly better problem-solving skills and a reduced neophobic response to a novel foraging situation, suggesting that selection may produce a suite of complex cognitive traits that could enhance survival in harsh conditions.…”

“…The same boxes were used for transport and the lighting and temperature conditions were similar in both cases. A detailed description of collection and housing procedures can be found in the study of Roth et al [23].…”

“…two Alaska and two Kansas) tested simultaneously. We used a caching array of 1.5 cm wells drilled into a wooden board (size 40 Â 18 cm; see also [23]) in a 3 Â 5 grid arrangement. A black, craft 'pom-pom' ball was inserted into each well; all birds were able to remove the balls from the wells.…”

Behavioural flexibility and problem-solving in a tropical lizard

“…a single presentation), they needed at least three times fewer presentations to successfully complete the associative learning tasks than what is commonly used in studies testing similar abilities in bird species (e.g. [9,10,14,15] and references therein). This result was unexpected and suggests a possible difference in the tempo at which associations are formed between these groups; further studies are needed to explore the generality of these results.…”

“…The behavioural paradigm used in our experiment is similar to that used in studies evaluating cognitive abilities of birds (e.g. [10,14]), which provides an opportunity to evaluate similarities and/or differences in cognitive performance across the two groups [4]. However, because distinct taxa might perceive the same cognitive task differently, we only explore the most basic aspect of the task: number of presentations.…”