Oceanic islands offer special opportunities for understanding the patterns and processes of evolution. The availability of molecular markers in recent decades has enhanced these opportunities, facilitating the use of population genetics to reveal divergence and speciation in island systems. A common pattern seen in taxa on oceanic islands is a decreased level of genetic variation within and among populations, and the founder effect has often been invoked to explain this observation. Founder effects have a major impact on immigrant populations, but, over millions of years, the original genetic signature will normally be erased as a result of mutation, recombination, drift and selection. Therefore, the types and degrees of genetic modifications that occur must often be caused by other factors, which should be considered when explaining the patterns of genetic variation. The age of the island is extremely important because oceanic islands subside on their submarine plates over time. Erosion caused by wind, rain and wave action combine to grind down soft volcanic substrates. These geomorphological events can have a dramatic impact on population number and size, and hence levels of genetic diversity. The mode of speciation is also of significance. With anagenesis, genetic variation accumulates through time, whereas, with cladogenenesis, the gene pool splits into populations of adaptively radiating species. Breeding systems, population sizes and generation times are also important, as is hybridization between closely related taxa. Human disturbance has affected plant population number and size through the harvesting of forests and the introduction of invasive plants and animals. Therefore, the explanation of the observed levels of genetic variation in species of oceanic islands requires the consideration of many interconnected physical, biological and anthropomorphic factors.

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大洋岛屿特有植物物种遗传变异模式的解释

大洋岛屿为理解进化的模式和过程提供了特殊的机会。近几十年来分子标记的可用性增加了这些机会，促进了利用种群遗传学来揭示岛屿系统中的差异和物种形成。在海洋岛屿的分类群中看到的一个常见模式是种群内部和种群之间的遗传变异水平降低，并且经常援引创始人效应来解释这一观察结果。创始人效应对移民人口有重大影响，但经过数百万年，原始遗传特征通常会因突变、重组、漂移和选择而被抹去。因此，发生的基因改造的类型和程度往往是由其他因素引起的，在解释遗传变异的模式时应该考虑这一点。岛屿的年龄非常重要，因为海洋岛屿会随着时间的推移在海底板块下沉。风、雨和波浪作用造成的侵蚀结合在一起磨碎了柔软的火山基底。这些地貌事件会对种群数量和规模产生巨大影响，从而对遗传多样性水平产生巨大影响。物种形成的模式也很重要。在再生过程中，遗传变异会随着时间的推移而积累，而在枝状发生过程中，基因库会分裂成具有适应性辐射的物种种群。育种系统、种群大小和世代时间也很重要，密切相关的分类群之间的杂交也很重要。人为干扰通过砍伐森林和引入入侵植物和动物影响了植物种群数量和大小。因此，对观察到的海洋岛屿物种遗传变异水平的解释需要考虑许多相互关联的物理、生物和拟人化因素。