The Impact of Late Quaternary Climate Change on Mammals Along an Elevational Gradient

本研究探讨了近15000年来沿高度和环境梯度变化的木鼠对气候变化的响应。更新世期间，曼利湖覆盖了死亡谷的大部分地区；它在全新世中期的突然干涸导致了温度和干旱的剧烈变化。今天，这个地区是西半球最热、最干燥的地区。通过结合实地考察、博物馆标本检查和古化石收集，该项目将重建来自谷底和附近山脉梯度（-84至3400米）的动物的不同进化历史。研究人员预测了与地点海拔和当地小气候相关的木鼠物种适应能力的根本差异。预测的响应包括：i)超过温度阈值时的局部灭绝，ii)产生新的适应，如新的生活史，以及iii)形态改变，如体型的表型变化。这项工作的更广泛的影响包括能够描述温度变化的幅度和速度之间的关系，地理范围内的位置，以及所阐明的响应类型。这些关于生物对过去气候变化的反应的信息对于研究人为变暖的科学家来说是无价的。此外，该项目将产生一个高质量的空间和时间分辨率的气候代理，可以与其他古数据相结合。晚第四纪气候的特征和解释是政府和地球科学机构的主要研究工作。

This study investigates the response of Neotoma (woodrats) to climatic change over the last 15,000 years along a severe elevational and environmental gradient. During the Pleistocene, lake Manly covered much of Death Valley; its abrupt draining in the mid-Holocene led to dramatic shifts in temperature and aridity. Today this area is the hottest and driest in the Western Hemisphere. By combining fieldwork, examination of museum specimens, and collection of paleofossils, this project will reconstruct the divergent evolutionary histories of animals from the Valley floor and along a nearby mountain gradient (-84 to 3400m). The investigators predict fundamental differences in the adaptive abilities of woodrat species related to elevation of the site and local microclimate. Predicted responses include: i) local extirpation when temperature thresholds are exceeded, ii) generation of novel adaptations, such as new life histories, and iii) morphological alterations, such as phenotypic changes in body size. The broader impacts of the work include the ability to characterize the relationship between the magnitude and rapidity of temperature shifts, the position in the geographic range, and the type of elucidated response. Such information about the responses of organisms to past climate change is invaluable for scientists studying anthropogenic warming. Moreover, the project will generate a high quality spatial and temporally resolved climate proxy that can be integrated with other paleodata. The characterization and interpretation of late Quaternary climates is a major research effort of governmental and geoscience agencies.