110.4 Saturday, Jan. 7 Variation in memory and the hippocampus across populations from different climates: a common garden approach ROTH, TC*; LADAGE, LD; FREAS, CA; PRAVOSUDOV, VV; Kenyon College; Univ. of Nevada, Reno; Univ. of Nevada, Reno; Univ. of Nevada, Reno firstname.lastname@example.org
Selection for enhanced cognitive traits is hypothesized to produce enhancements to brain structures that support those traits. Although many studies suggest that this pattern is robust, there are several mechanisms that may produce this association. First, cognitive traits and their neural underpinnings may be fixed as a result of differential selection on cognitive function within specific environments. Second, these relationships may be the product of plasticity, where differences are produced due to an individual’s experiences in the environment. Alternatively, the relationship may be a complex function of experience, genetics, and/or epigenetic effects. Using a well-studied model species (black-capped chickadee, Poecile atricapillus), we have addressed these hypotheses. We found that differences in hippocampal (Hp) neuron number, neurogenesis, and spatial memory previously-observed in wild chickadees persisted in hand-raised birds from the same populations, even when birds were raised in an identical environment. These findings reject the hypothesis that variation in these traits is due solely to differences in memory-based experiences in different environments. Moreover, neuron number and neurogenesis were strikingly similar between captive-raised and wild birds from the same populations further supporting the genetic hypothesis. Hp volume, however, did not differ between the captive-raised populations, yet was very different in their wild counterparts, supporting the experience hypothesis. Our results indicate that the production of some Hp factors may be inherited and largely independent of environmental experiences in adult life, regardless of their magnitude, in animals under high selection pressure for memory, while traits such as volume may be more plastic and modified by the environment.