DISSERTATION RESEARCH: Estimating the genetic and demographic response of an amphibian metapopulation to global climate change

该项目将对比人口规模估计和移民估计在预测人口下降和增加方面的效用。众所周知，太小的种群可能会经历高水平的近亲交配，并可能随着时间的推移失去大部分遗传多样性。反过来，它们可能面临更高的灭绝概率，因此，种群规模可能是许多保护计划中的一个关键变量。然而，当更多的力量在起作用时，人口规模可能不能很好地预测人口的生存能力。在预测人口生存可能性的长期趋势方面，不同地点之间的迁移以及气候引起的人口年年波动可能与平均人口规模一样重要。研究人员将检验平均种群大小、种群间迁徙和种群变异性在预测两个蜥蜴物种种群生存能力方面的相对有效性。该项目将开发更多信息丰富的遗传监测技术，并培训一名博士生。该项目将确定在同一湿地监测了37年的两种火蜥蜴的有效种群数量(Ne)和基因流动模式。在过去的15年里，其中一种，不透明Ambystoma opacum，数量在增加，而另一种，Ambystoma talpoideum，数量在减少。这项研究将回答两个问题：第一，NE作为种群生存能力预测指标的可靠性是否依赖于集合种群结构？第二，基因流动和繁殖率的年度波动如何影响种群的长期生存能力？关于基因流如何影响基于Ne的生存能力估计的问题，将通过使用下一代测序从五个相连的亚群中收集个体的单核苷酸多态数据来解决。这两个物种的最大似然估计值和基因流动率的贝叶斯估计值都会被计算出来。集合种群结构在精炼基于Ne的结论中的重要性将从该数据中确定对于下降和增长的种群。前几年以个人为基础的人口普查数据将被用来根据从基因样本中获得的真相估计。然后将开发预测模型，以预测每个物种的集合种群是否面临灭绝的风险，或者如果预计只有个别亚种群随着时间的推移而丧失和重新殖民。

This project will contrast the utility of population size estimates and migration estimates in predicting population declines and increases. It is known that populations that are too small can experience high levels of inbreeding and may lose much of their genetic diversity over time. In turn they may face higher extinction probabilities and for this reason population size could be a critical variable in many conservation plans. Population size, however, may be a poor predictor of a population's viability when additional forces are at play. Migration between locations as well as climate induced fluctuations in a population from year to year may be just as important as the average population size in predicting long term trends in a population's likelihood of survival. The researchers will examine the relative effectiveness of average population size, migration between populations and population variability in predicting the viability of populations of two salamander species. The project will develop more informative genetic monitoring techniques as well as the training of a doctoral student.This project will determine the effective population size (Ne), and gene flow patterns of two salamander species that have been monitored in the same wetland for 37 years. One of the species, Ambystoma opacum, is increasing in number while the other, Ambystoma talpoideum, is decreasing in number over the last fifteen years. This study will answer two questions: First, is the reliability of Ne as a predictor of population viability dependent on metapopulation structure? Second, how do gene flow and annual fluctuations in reproductive rate influence the long-term viability of populations? The question of how gene flow impacts viability estimates based on Ne will be addressed by collecting Single Nucleotide Polymorphism data from individuals from five connected subpopulations using next generation sequencing. Maximum likelihood estimates of Ne for the subpopulations, and Bayesian estimates of gene flow rates between the subpopulations will be calculated for both species. The importance of metapopulation structure in refining conclusions based on Ne will be determined for both declining and growing populations from that data. Individual based census data from previous years will be used to ground truth estimates obtained from genetic samples. Projection models will then be developed to predict whether the metapopulation of each species is at risk for extinction or if only individual subpopulations are expected be lost and recolonized over time.