Genetic rescue in an isolated metapopulation of a naturally fragmented plant species, Parnassia palustris
Genetic rescue in an isolated metapopulation of a naturally fragmented plant species, Parnassia palustris
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DOI：
10.1111/j.1523-1739.2006.00645.x
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发表时间：
2007-06-01
影响因子：
6.3
通讯作者：
Bossuyt, Beatrijs
中科院分区：
文献类型：
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作者：
Bossuyt, Beatrijs
自然分散的物种栖息地的丧失可能会导致孤立的集合种群：仍然通过基因流联系在一起但已与其他集合种群隔离的小群体。遗传隔离可能导致之间的遗传分化。集合种群并降低集合种群内的遗传多样性。因此，来自集合群体外部的基因输入有望增强交叉相容性和种子活力。同时，由于小种群中的遗传漂变、近亲繁殖和花粉限制，适应度可能会随着集合种群内种群规模的增加而增加。我在比利时西部和法国西北部海岸 15 x 0.5 公里的研究区域中，在濒危植物 Parnassia palustris L. 的三个孤立的集合种群中测试了这些假设。在分布于三个集合种群的 27 个种群中测量的种子和果实重量在集合种群之间存在显着差异，这表明遗传分化。这些适应度变量也随着两个集合种群内的种群规模而增加。通过授粉实验，我研究了用来自另一个集合种群的花粉进行基因拯救是否增强了种子集。集合种群外杂交比集合种群内杂交产生的种子数显着更高，并且这种效应在小种群中更为明显。这意味着来自集合种群外部的花粉比来自集合种群内部的花粉更相容，因为集合种群内的遗传多样性较低。自然授粉花的种子数至少与人工授粉花的种子数相等，这可以通过花粉数量和供体多样性对花粉质量的补偿效应来解释。人们可以假设，集合种群水平上遗传多样性的丧失影响的基因座不仅仅与交叉相容性有关。通过踏脚石重新连接集合种群可能是必要的，以防止进一步的遗传侵蚀并确保研究区域内帕纳西亚种群的长期生存能力。
The loss of habitat of naturally fragmented species may result in isolated metapopulations: small groups of populations that are still connected by gene flow but have become isolated from other metapopulations. Genetic isolation may result in genetic differentiation between. metapopulations and lowered genetic diversity within the metapopulation. Gene input from outside the metapopulation can hence be expected to enhance crosscompatibility and seed viability. Simultaneously due to genetic drift, inbreeding, and pollen limitation in the small populations, fitness is likely to increase with population size within a metapopulation. I tested these hypotheses in three isolated metapopulations of the endangered plant species Parnassia palustris L. in a study area of 15 x 0.5 km along the coast of western Belgium and northwestern France. Seed and fruit weight, measured in the 27 populations distributed over the three metapopulations, significantly differed among the metapopulations, which suggests genetic differentiation. These fitness variables also increased with population size within two metapopulations. With a pollination experiment, I investigated whether genetic rescue with pollen from another metapopulation enhanced seed set. Outside-metapopulation crosses led to a significantly higher seed set than within-metapopulation crosses, and this effect was more pronounced in small populations. This means pollen from outside the metapopulation was more compatible than pollen from within the metapopulation, due to a lowered genetic diversity within the metapopulation. The seed set of naturally pollinated flowers was at least equal to that of hand pollinated flowers, which can be explained by a compensation effect of pollen quantity and donor diversity for pollen quality. One can assume that the loss of genetic diversity at the level of the metapopulation affected loci not just related to cross compatibility. Reconnection of metapopulations by stepping stones may be necessary to prevent further genetic erosion and assure the viability of the Parnassia populations in the study area over the long term.