Collaborative: Mammalian Phylogeography in Regional Warm Deserts of North America

[9629840 . HAFNER]最近在北美西南部出现了大面积的干旱地区，这使许多人认为适应这些地区的动植物之间的关系模式也是最近才出现的。然而，许多物种都很古老，在分散的干旱地区生存了数百万年。在合作调查中，大卫·j·哈夫纳和布雷特·r·里德尔将与他们的合作者一起调查区域沙漠中古代结构的可能性，并重建这些沙漠的分化顺序。他们将通过线粒体DNA的序列差异来研究四组啮齿动物之间的遗传关系。这些啮齿类动物目前仅限于区域温暖的沙漠和邻近的灌木丛或灌木栖息地，化石记录表明它们在区域沙漠发展的早期就存在于研究区域，可达550万年前。这些啮齿动物之间的关系将作为沙漠中其他动物和植物之间关系的指标。哈夫内罗博士的部分合作将包括收集和鉴定啮齿动物群体，其中包括白足鼠和口袋鼠，羚羊地松鼠和袋鼠鼠，以检测它们的线粒体DNA。探险队将在美国西南部和墨西哥北部的奇瓦瓦、大盆地、圣华金、索诺兰和半岛沙漠中的33个地点进行探险，以及邻近的加利福尼亚丛林和锡那罗亚刺丛地区，以及下加利福尼亚州的六个岛屿。这些岛屿样本有望提供大约5000年前下加利福尼亚半岛大陆上啮齿动物的地理分布估计，当时这些岛屿与半岛分离。参与者包括墨西哥国立自治大学和下加利福尼亚南部生物研究中心的里德尔博士及其同事。这项研究有望有助于人类了解物种和物种分布如何随时间变化，特别是物种的这种变化如何受到物种所在地区的拓扑结构和气候变化的影响。

9629840 HAFNER The recent appearance of extensive regions of aridlands in southwestern North America has led many to assume that pattersn of relationships among the plants and animals adapted to these regions are also recent. Yet many of the species are ancient, having persisted in scattered dry sites for many millions of years. In collaborative investigations, David J. Hafner and Brett R. Riddle, together with their collaborators, will investigate the possibility of ancient structure among the regional deserts and reconstruct the sequence of divergence of these deserts. They will examine, by means of sequence divergences in mitochondrial DNA, the genetic relationships among four groups of rodents. These rodents are currently restricted to regional warm deserts and neighboring chaparral or thornscrub habitats, and have fossil records that indicate their presence in the study area during the early development of the regional deserts, up to 5.5 million years ago. Relationships among these rodents will serve as indicators of relationships among other animals and plants in the deserts. Dr. HafnerOs portion of the collaboration will involve collection and identification of the groups of rodents, which include white-footed and pocket mice, antelope ground squirrels, and kangaroo rats, targeted for examination of their mitochondrial DNA. Expeditions will be made to up to 33 sites in the Chihuahuan, Great Basin, San Joaquin, Sonoran, and Peninsular deserts of the southwestern United States and northern Mexico, as well as the neighboring California chaparral and Sinaloan thornscrub regions, and six islands off Baja California. The island samples are expected to provide estimates of the geographic distribution of the rodents on the Baja California peninsular mainland ca. 5,000 years ago, when the islands were separated from the peninsula. Participants include Dr. Riddle and colleagues at the Universidad Nacional Autonoma de Mexico and the Centro de Investigaciones Biologicas de Baja Californi a Sur. The research is expected to contribute to human understanding of how species, and the distribution of species, change over time, and especially how such changes in species may be influenced by changes in the topology and climate of the regions in which the species live.