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

这个项目将对比人口规模估计和迁移估计在预测人口减少和增加方面的效用。众所周知，过小的种群可能会经历高水平的近亲繁殖，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，在许多保护计划中，种群规模可能是一个关键变量。然而，当有额外的力量在起作用时，种群规模可能并不能很好地预测种群的生存能力。在预测人口生存可能性的长期趋势方面，地点之间的迁移以及气候引起的人口年复一年的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规模、种群间迁移和种群变异在预测两种蝾螈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基因监测技术，并培养一名博士生。该项目将确定在同一湿地监测了37年的两种蝾螈的有效种群规模（Ne）和基因流动模式。其中一种，Ambystoma opacum，在数量上正在增加，而另一种，Ambystoma talpoideum，在数量上在过去的15年里正在减少。本研究将回答两个问题：第一，作为种群生存能力预测因子的Ne的可靠性是否依赖于元种群结构？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？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连接的亚群中收集个体的单核苷酸多态性数据来解决。将计算两个物种的亚种群的Ne的最大似然估计值和亚种群之间基因流率的贝叶斯估计值。元人口结构在改进基于Ne的结论中的重要性将根据该数据确定人口下降和增长的情况。前几年基于个人的人口普查数据将用于从基因样本中获得的真实估计。然后将开发预测模型来预测每个物种的大种群是否有灭绝的危险，或者是否只有个别的亚种群预计会随着时间的推移而消失并重新定居。

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.