Finding and establishing new subpopulations

当一个动物亚种群灭绝时，剩余的个体分散寻找新的栖息地，开始新的亚种群。我计划研究这一过程的三个步骤——寻找、发现栖息地斑块和在这些栖息地斑块中建立亚种群。我建议找出哪种类型的运动模式对于寻找栖息地斑块是最成功的，这种成功如何取决于栖息地斑块的分布，小型哺乳动物在未知栖息地旅行时实际使用哪种运动模式，以及所使用的运动模式类型如何取决于栖息地类型。我还将测量在实验操纵的栖息地中，小型哺乳动物的感知范围（它们能从多远的地方探测到栖息地斑块）是如何随着栖息地和离家园范围的距离而变化的。野外实验将使用小型哺乳动物（田鼠和小鼠）进行。这些动物价格低廉，易于研究，使我们能够很快获得大量样本。这些动物将通过无线电遥测和线轴跟踪相结合的方式进行追踪。运动路径将使用一种新开发的统计技术进行分析，该技术可以区分随机运动和定向运动。一旦动物找到了一个新的栖息地，它们就需要建立一个新的亚种群。我的研究的第三部分将着眼于在可变环境中建立新的亚种群。当亚种群很小时，随机事件对成功的几率有很大的影响。我还建议找出人口规模如何影响生存概率，以及环境的可变性如何影响存活率。这项工作将用海狸来完成。随机事件是冲垮水坝的风暴。当水坝很小的时候，它们很容易被风暴冲垮。我建议对大面积的水坝进行调查，然后比较不同季节水坝的成功情况，作为水坝规模和风暴规模的函数。

When a subpopulation of animals goes extinct, then residual individuals disperse in search of new habitat patches to start new subpopulations. I plan to study three steps of this process - searching, discovering habitat patches, and establishing subpopulations in those habitat patches.     I propose to find out which types of movement patterns are most successful for finding habitat patches, how this success depends on the distribution of habitat patches, which movement patterns do small mammals actually use when travelling in unknown habitats, and how the type of movement pattern used depends on habitat type. I will also measure how perceptual range (from how far away they can detect the habitat patches) varies with habitat and distance from home range for small mammals in experimentally manipulated habitats.     The field experiments will be carried out using small mammals (voles and mice). These animals are cheap and easy to work with, allowing us to get large sample sizes quite quickly. The animals would be tracked using a combination of radio-telemetry and thread-spooling. Movement paths would be analysed using a newly-developed statistical technique that differentiates between random and directed movement.     Once animals find a new habitat patch, they need to establish a new subpopulation. The third part of my research will look at the establishment of new subpopulations in variable environments. When subpopulations are small, random events have a large impact on the chance of success.     I also propose to find out how population size affects survival probability, and how variability in conditions affects survival rate.     This work would be carried out using beavers. The random events are storms that wash out dams. When dams are small, they are easily washed out by storms. I propose to survey dams over a large area, and then compare the success of the dams from one season to the next, as a function of dam size and size of storms.