DISSERTATION RESEARCH: Temperature gradients along latitude and elevation: Effects on dispersal

热带地区的高地总是比低地冷；气温不像温带高原那样随季节变化。因此，热带山地生物可能适应较窄的温度范围，因此在生理上无法上山或下山。相比之下，温带山地生物可能由于季节循环而适应更宽的温度范围，这使它们更有可能在海拔高度之间移动。这个被称为Janzen效应的预测解释了为什么在热带地区，不同的海拔高度有不同的物种，而在温带地区，一个给定的物种可以生活在不同的海拔高度。关于Janzen效应的测试很少。这项研究将确定Janzen效应是否发生在安第斯蛙类中。换句话说，热带安第斯山脉的青蛙物种是否比温带安第斯山脉的青蛙物种更少地向上或向下移动？移动速度将使用基因技术来估计。这项研究将有助于了解热带动物多样化的机制。这个项目的意义延伸到所有的变温动物（“冷血动物”），因为它们的生理直接受到外部环境的影响。这项研究将预测一些生物种群是否对全球变暖导致的山地气候变化更有弹性。来自安第斯山脉小城镇的学生将积极参与与共同项目负责人关于他们自己的安第斯动植物的起源和多样化的科学讨论，并将直接接触分子进化方面的当前实地技术和程序。

Tropical-zone highlands are always colder than lowlands; temperatures do not change across seasons the way they do in temperate-zone highlands. As a result, tropical montane organisms may be adapted to narrow temperature ranges and thus physiologically incapable of moving up or down mountains. In contrast temperate montane organisms are probably adapted to wider temperature ranges due to seasonal cycles, making them more likely to move between elevations. This prediction, called the Janzen Effect, explains why in tropical regions different elevations hold different species whereas in temperate regions a given species can live at a range of altitudes. Very few tests of the Janzen Effect exist. This research will determine if the Janzen Effect occurs in Andean frog species. In other words, do frog species in the tropical Andes move up or down the mountains less often than species in the temperate Andes? Movement rates will be estimated using genetic techniques. This study will help to understand the mechanisms of diversification of tropical animals.The implications of this project extend to all ectotherms ("cold blooded animals"), because their physiology is directly affected by the external environment. This study will produce predictions about whether some populations of organisms might be more resilient to montane climate variation resulting from global warming. Students from small towns in the Andes will actively participate in scientific discussions with the Co-PI about the origin and diversification of their own Andean flora and fauna and will have direct contact with current field techniques and procedures in molecular evolution.