岛屿种群遗传多样性是否低于大陆种群

熊荣川 译

   岛屿种群比大陆种群更容易灭绝，其原因仍存争议。考虑到近亲繁殖而导致的遗传多样性丢失，岛屿种群的遗传多样性必然小于大陆种群。通过分析已经发布的在、核DNA标记，线粒体DNA、以及染色体倒置和数量性状上等水平的遗传多样性，发现绝大部分的岛屿种群的等位基因酶遗传多样性低于它们的大陆参照（占202个对比案例中的165个），多样性平均下降29%。这个巨大的差异与扩散能力有关。在其它的多样性比较中也存在相应的差异。在38个研究个案中，34例结果表明岛屿特有物种比大陆物种的遗传多样性低。在哺乳类和鸟类中，岛屿特有物种的遗传多样性下降程度明显高于非岛屿特有物种，在昆虫中这没有同样的现象。遗传因素不能排除导致岛屿种群比起大陆种群有更高灭绝几率的嫌疑。

关键词：等位基因酶 保持 特有物种 灭绝 遗传多样性 岛屿

原文：

Do island populations have less genetic variation than mainland populations?

Island populations are much more prone to extinction than mainland populations. The reasons for this remain controversial. If inbreeding and loss of genetic variation are involved, then genetic variation must be lower on average in island than mainland populations. Published data on levels of genetic variation for allozymes, nuclear DNA markers, mitochondrial DNA, inversions and quantitative characters in island and mainland populations were analysed. A large and highly significant majority of island populations have less allozyme genetic variation than their mainland counterparts (165 of 202 comparisons), the average reduction being 29 percent. The magnitude of differences was related to dispersal ability. There were related differences for all the other measures. Island endemic species showed lower genetic variation than related mainland species in 34 of 38 cases. The proportionate reduction in genetic variation was significantly greater in island endemic than in nonendemic island populations in mammals and birds, but not in insects. Genetic factors cannot be discounted as a cause of higher extinction rates of island than mainland populations.

Keywords: allozymes, conservation, endemic species, extinction, genetic variation, islands.

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