Collaborative Research: Mammalian Phylogeography in Regional Warm Deserts of North America

9629787谜语最近北美西南部的大片艾里德兰地区出现，导致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，许多物种都是古老的，在零星干燥的地方生存了数百万年。在合作研究中，布雷特·R·里德尔和大卫·J·哈夫纳将与他们的合作者一起，调查区域沙漠之间古代结构的可能性，并重建这些沙漠的分化序列。他们将通过线粒体DNA的序列差异来研究四类啮齿动物之间的遗传关系。这些啮齿动物目前仅限于地区性温暖的沙漠和邻近的查帕尔或荆棘灌木丛栖息地，并有化石记录表明，在550万年前的地区性沙漠早期发展期间，它们曾出现在研究区域。这些啮齿动物之间的关系将成为沙漠中其他动植物之间关系的指示器。Riddleos博士的部分合作将涉及对啮齿类动物群体的线粒体DNA进行检查，这些啮齿类动物包括白脚和口袋鼠、羚羊松鼠和袋鼠。这些动物将在美国西南部和墨西哥北部的奇瓦瓦、大盆地、圣华金、索诺兰和半岛沙漠以及邻近的加利福尼亚州夏帕拉尔和西那罗亚荆棘灌木丛地区以及下加利福尼亚州附近的六个岛屿的野外工作中收集。这些岛屿样本预计将提供大约5000年前下加利福尼亚半岛大陆啮齿动物地理分布的估计，当时这些岛屿与半岛分离。从线粒体DNA中分离出来的基因序列将被测序，并将用于构建系统发育树，以测试动物之间的关系程度。这项研究有望帮助人类了解物种及其分布随时间的变化，特别是物种所在地区的地形和气候变化对物种变化的影响。

9629787 RIDDLE 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, Brett R. Riddle and David J. Hafner, 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. RiddleOs portion of the collaboration will involve examination of the mitochondrial DNA of the groups of rodents, which include white-footed and pocket mice, antelope ground squirrels, and kangaroo rats. These animals will be collected during field work 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. Gene sequences isolated from the mitochondrial DNAs will be sequenced, and the sequences used to construct phylogenetic trees that will test the degree of relationships among the animals. The re search 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.