CRB: Demographic and Genetic Factors in Extinction

WPCD 2 B v p z 10cpi ? x x x， X 6 x @ 8; X@ HP DeskJet 500 HPDES500.PRS X @ x X，，0 FX@#|X 2 B 小行星9225127 该项目的目标是制定和分析影响种群灭绝风险的人口和遗传因素及其相互作用的数学模型。要调查的人口因素包括随机灾害及其与波动环境的相互作用，在空间分布的"集合种群"中的局部灭绝和殖民化，以及在波动环境中的种群收获。 研究的遗传因素包括小群体的近亲繁殖、有害突变、随机遗传漂变和环境变化中的适应性进化。将采用动力系统理论和随机过程理论的方法，例如将波动环境和随机遗传漂变建模为扩散过程，将随机灾难建模为跳跃过程。 主要的兴趣量是灭绝的时间和概率，特别是平均灭绝时间。 使用适当的近似，简单的公式将推导出阐明与每个因素及其相互作用相关的灭绝风险。 在可行的情况下，分析结果将通过计算机模拟进行检查。研究结果将有助于为保护生物学建立更坚实的理论基础。 更好地了解导致灭绝的因素，特别是在小种群中，将立即应用于生存能力分析，以及受威胁和濒危物种的保护和恢复计划。***

WPCD 2 B V P Z Courier 10cpi ? x x x , x 6 X @ 8 ; X @ HP DeskJet 500 HPDES500.PRS x @ x X , , 0 FX @ #| x 2 B 9225127 Lande The goals of this project are to formulate and analyze mathematical models of demographic and genetic factors and their interactions affecting the risk of population extinction. Demographic factors to be investigated include random catastrophes and their interaction with fluctuating environments, local extinction and colonization in spatially distributed "metapopulations", and harvesting of populations in a fluctuating environment. Genetic factors to be investigated include inbreeding in small populations, deleterious mutation, random genetic drift, and adaptive evolution in changing environments. Methods from dynamical system theory and stochastic process theory will be employed, e.g. modeling fluctuating environments and random genetic drift as diffusion processes, and random catastrophes as a jump process. The main quantities of interest are times and probabilities of extinction, especially the mean time to extinction. Using suitable approximations, simple formulas will be derive that elucidate the extinction risks associated with each factor and their interactions. Analytical results will be checked by computer simulation where feasible. %%% The results will help to establish a stronger theoretical foundation for the science of conservation biology. A better understanding of factors causing extinction, particularly in small populations, will have immediate applications in viability analysis, and in conservation and restoration plans for threatened and endangered species. ***