Dissertation Research: Adaptive behavioral and physiological changes among populations undergoing range expansion

外来物种在其引进范围内造成重大的生态和经济破坏；识别入侵的预测因子以防止未来的入侵是很重要的。这些信息在评估本地物种对环境变化的脆弱性方面也可能被证明是重要的。最近的一个引进事件，家雀（Passer domesticus）到肯尼亚，仍然在扩展到最初的引进地点之外。肯尼亚家麻雀没有很高的遗传多样性，但仍然表现出广泛的行为和生理变异；有趣的是，观察到的变化与估计的人口年龄相关。靠近范围边缘的家麻雀比靠近最初引入地点的家麻雀更具探索性，在应对压力源时释放更多的应激激素（糖皮质激素）。然而，这些特征差异在适应度方面意味着什么，沿着范围扩展是未知的；此外，在缺乏遗传多样性的情况下，这些差异是如何产生的也是未知的。本研究的目的是确定A)探索和应激激素的增加是否会在范围边缘带来适应性优势，但在更熟悉的栖息地则会带来劣势；B)这些差异是否由于后代发育过程中母亲照顾的差异而产生。为了验证这些问题，将在肯尼亚进行观察，观察自然的亲代照料以及在巢箱殖民地的雏鸟时期对母亲提供食物能力的操纵。PI预测，探索和应激激素的增加增加了范围边缘的适应度，但降低了引入点的适应度。此外，还预计食物补充将产生与引入地点自然发生的后代最相似的后代，而减少供应将产生与范围边缘相似的后代。拟议的研究将加强国际合作，并为代表性不足的少数族裔STEM本科生提供研究机会。

Non-native species cause major ecological and economic damage in their introduced range; it is important to identify predictors of invasiveness to prevent future invasions. This information might also prove to be important is assessing the vulnerability of native species to environmental change. One of the most recent introduction events, the house sparrow (Passer domesticus) to Kenya, is still expanding beyond the site of initial introduction. Kenyan house sparrows do not have high genetic diversity, however still exhibit extensive behavioral and physiological variation; interestingly, the observed variation is correlated with the estimated age of the population. House sparrows closest to the edge of the range are more exploratory and release more stress hormones (glucocorticoids) in response to stressors than those closer to the site of initial introduction. However, what these trait differences mean in terms of fitness along the range expansion is unknown; further, how these differences arise given the lack of genetic diversity is also unknown. The goal of the present research is to determine A) if increased exploration and stress hormones grant a fitness advantage at the range edge, but a disadvantage in more familiar habitats; and B) whether these differences arise due to differences in maternal care during offspring development. To test these questions, observation of natural parental care as well as manipulattion of a mother's ability to provision during the nestling period in nestbox colonies will be carried out in Kenya. The PI predicts that increased exploration and stress hormones increase fitness at the edge of a range, but decrease it at the site of introduction. Further, it is also expected that food supplementation will generate offspring most like those naturally occurring at the site of introduction and a reduction of provisioning will produce offspring similar to those at the range edge. The proposed study will strengthen international collaborations and provide research opportunities for underrepresented minority STEM undergraduates.