Inbreeding Depression in Metapopulations: Epistasis and Purging

本研究调查了基因相互作用对近亲繁殖抑制的贡献，影响近亲后代的生存能力和繁殖能力的下降。经过许多代，近交抑制可以被减轻或“清除”，因为自然选择从近交种群中去除有害基因和基因组合。本研究采用理论与实验相结合的方法，以粉甲虫为模型系统，对其近交抑制率、单基因和基因组合的清除率进行了研究。管理濒危物种遗传的保护策略使用精心设计的谱系，以尽量减少近亲繁殖的抑制。因为它们减少了近亲繁殖，它们必然减少了清洗。这些管理策略是基于单基因理论。当近亲繁殖衰退是由基因相互作用引起时，它的积累速度可能比单基因理论预期的要快或慢。因此，当前的保护实践可能要么过于复杂，要么无法达到减少近亲繁殖衰退的目标。此外，从长远来看，近亲繁殖和净化之间的平衡可能是最好的策略。在基因相互作用中，通过选择清除有害的相互作用基因群，并且比单基因理论预测的速度要快得多，单基因理论预测的是基因一次一个地独立去除。

This research investigates the contribution of gene interactions to inbreeding depression, the decline in viability and reproduction that affects the offspring of close genetic relatives. Over many generations, inbreeding depression can be mitigated or "purged" as natural selection removes deleterious genes and gene combinations from inbreeding populations. Using a combination of theory and experiment, with flour beetles as the model system, this research investigates the rate of inbreeding depression and the rate of purging for single genes and gene combinations. Conservation strategies for managing the genetics of endangered species use elaborate pedigrees designed to minimize inbreeding depression. Because they mitigate inbreeding, they necessarily mitigate purging. These management strategies are based upon single-gene theory. When inbreeding depression is caused by gene interactions, it can accumulate faster or slower than expected from single-gene theory. Thus, current conservation practice might be either overly elaborate or hopelessly inadequate for its goal of minimizing inbreeding depression. In addition, a balance between inbreeding and purging might represent the best strategy in the long run. With gene interactions, purging by selection removes groups of deleterious interacting genes and be much faster than the rate predicted by single-gene theory, where genes are removed independently, one at a time.