Data from: Population genetic structure and its implications for adaptive variation in memory and the hippocampus on a continental scale in food-caching black-capped chickadees

Food-caching birds rely on stored food to survive the winter and spatial memory has been shown to be critical in successful cache recovery. Both spatial memory and the hippocampus, an area of the brain involved in spatial memory, exhibit significant geographic variation linked to climate-based environmental harshness and the potential reliance on food caches for survival. Such geographic variation has been suggested to have a heritable basis associated with differential selection. Here, we ask whether population genetic differentiation and potential isolation among multiple populations of food-caching black-capped chickadees is associated with differences in memory and hippocampal morphology by exploring population genetic structure within and among groups of populations that are divergent to different degrees in hippocampal morphology. Using mitochondrial DNA and 583 AFLP loci, we found that population divergence in hippocampal morphology is not significantly associated with neutral genetic divergence or geographic distance, but instead is significantly associated with differences in winter climate. These results are consistent with variation in a history of natural selection on memory and hippocampal morphology that creates and maintains differences in these traits regardless of population genetic structure and likely associated gene flow.

储食鸟类依赖储存的食物越冬，而空间记忆已被证实对成功取回储存的食物至关重要。空间记忆与参与空间记忆调控的大脑区域海马体（hippocampus），均表现出显著的地理变异，这种变异与基于气候的环境严酷程度以及越冬对储食的潜在依赖程度相关。这类地理变异被认为具有可遗传的基础，与差异化选择相关。本研究旨在探讨储食性黑头山雀多个种群间的种群遗传分化与潜在隔离，是否与记忆能力和海马体形态差异相关。具体而言，我们对海马体形态分化程度各异的种群组内及组间的种群遗传结构进行分析。本研究借助线粒体DNA与583个扩增片段长度多态性（AFLP）位点开展分析，结果发现，海马体形态的种群分化与中性遗传分化及地理距离均无显著关联，却与冬季气候差异显著相关。上述结果与记忆能力和海马体形态所经历的自然选择历史变异相符，这类选择无论种群遗传结构与潜在的基因流如何，均能塑造并维持这些性状的差异。