Genetic effects of recent habitat fragmentation in the Thousand-Island Lake region of southeast China on the distylous herb Hedyotis chrysotricha (Rubiaceae).
Genetic effects of recent habitat fragmentation in the Thousand-Island Lake region of southeast China on the distylous herb Hedyotis chrysotricha (Rubiaceae).
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DOI：
10.3732/ajb.1200054
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发表时间：
2012-10
影响因子：
3
通讯作者：
N. Yuan;H. Comes;Yun-Rui Mao;Xin-Shuai Qi;Y. Qiu
中科院分区：
文献类型：
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作者：
N. Yuan;H. Comes;Yun-Rui Mao;Xin-Shuai Qi;Y. Qiu
未知的研究前提已知年龄的人工湖岛屿提供了理想的模型系统来阐明最近时间尺度上人为生境破碎化的遗传和进化后果。本研究以中国东南部人工人工湖（TIL）地区的一种二花科草本植物黄花蛇舌草（Hedyotis chrysotricha）为研究对象，探讨了该物种被岛屿化的遗传后果。方法利用7个微卫星位点对来自18个种群的384个黄毛螺旋体个体进行基因分型，评估遗传多样性、种群结构和人口统计学参数。岛屿种群的平均遗传多样性显著低于西部/东部大陆种群（例如，H(E) = 0.381 vs. 0.461），但也表现出更高的平均细分（F(ST) = 0.12 vs. 0.042/0.051）。BayesAss的分析表明，大多数种群的迁移率处于中等水平，而“瓶颈”并没有为这种影响提供强有力的证据。因此，在研究区域，2MOD强烈倾向于基因流动-漂模型，而不是纯漂模型，但同时也揭示了漂在岛屿种群中相对更大的影响，这一点由等位基因共祖先的概率显著较高（F = 0.184 vs. 0.085）所证明。•结论：观察到的黄毛鼠遗传模式表明，TIL地区最近的人为栖息地破碎化可能导致孤立片段（岛屿）遗传多样性的显著丧失，原因是持续的漂流。相比之下，随机交配、基因流动和种群连通性的模式尚未得到很大的改变，这可能是由于物种的果实（种子）传播能力在面对栖息地碎片化时提供了弹性。
UNLABELLED PREMISE OF THE STUDY Known-age artificial-lake islands provide ideal model systems to elucidate the genetic and evolutionary consequences of anthropogenic habitat fragmentation on very recent time scales. Here, we studied a distylous herb, Hedyotis chrysotricha (Rubiaceae), in the artificially created Thousand-Island Lake (TIL) region of southeast China to explore the genetic consequences of islanding for this species. • METHODS Seven microsatellite loci were used to genotype 384 individuals of H. chrysotricha from 18 populations to estimate genetic diversity, population structure, and demographic parameters. • KEY RESULTS Island populations had significantly lower mean genetic diversity than those from the western/eastern mainland (e.g., H(E) = 0.381 vs. 0.461) and also displayed higher mean subdivision (F(ST) = 0.12 vs. 0.042/0.051). BayesAss analyses indicated moderate levels of migration rates among most populations, whereas Bottleneck did not provide strong evidence for such effects. In consequence, 2MOD strongly favored a gene flow-drift model over a pure drift model in the study area, but concomitantly revealed a relatively greater influence of drift in the island populations as evidenced by their significantly higher probabilities of allelic coancestry (F = 0.184 vs. 0.085). • CONCLUSIONS The observed genetic patterns in H. chrysotricha indicate that recent anthropogenic habitat fragmentation in the TIL region can lead to significant loss of genetic diversity in isolated fragments (islands) due to ongoing drift. By contrast, patterns of random mating, gene flow, and population connectivity have not greatly been modified yet, possibly owing to the species' fruit (seed) dispersal capabilities providing resilience in the face of habitat fragmentation.