Aguirre-Liguori Jonas A, Scheinvar Enrique, Eguiarte Luis E
Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Apartado Postal 70-275, Circuito exterior s/n junto al Jardín Botánico, Coyoacán, México, D.F. 04510 México.
Am J Bot. 2014 Apr;101(4):730-6. doi: 10.3732/ajb.1400031. Epub 2014 Apr 3.
Although species adapted to grow in unusual soils contribute importantly to regional diversity, the microevolutionary processes responsible for that diversity remain to be understood. We aimed to answer this question by analyzing which processes are responsible for the genetic differentiation in Fouquieria shrevei (Fouquieriaceae), a species confined to gypsum soils of northern Mexico.
We analyzed sequence variation in three chloroplast intergenic spacers from five populations.
Total genetic diversity was high (Hd = 0.743). Genetic differentiation was high (FST = 0.651), as most haplotypes were unique to individual populations, and three populations had only one haplotype. Haplotypes were more similar in nearby populations, resulting in a phylogeographic structure (i.e., GST = 0.850 was significantly lower than NST = 0.930) and a significant Mantel test (P = 0.04). Tajima's D (-0.019, not significant) indicates that effective population size has remained constant.
We conclude that genetic drift has been intense and gene flow low in differentiating populations that follow an island-like pattern of gypsum deposits of the deserts of North America. The interaction between these forces could promote speciation events that in turn would increase regional diversity and may explain the high number of narrow endemics associated with soil restrictions.
尽管适应在特殊土壤中生长的物种对区域多样性有重要贡献，但导致这种多样性的微观进化过程仍有待了解。我们旨在通过分析哪些过程导致了墨西哥北部石膏土壤特有的物种——希氏福桂花（刺树科）的遗传分化来回答这个问题。
我们分析了来自五个种群的三个叶绿体基因间隔区的序列变异。
总的遗传多样性较高（单倍型多样性 = 0.743）。遗传分化程度较高（固定指数 = 0.651），因为大多数单倍型是各个种群所特有的，并且有三个种群只有一种单倍型。附近种群的单倍型更为相似，形成了一个系统发育地理结构（即，基因流指数 = 0.850 显著低于标准化遗传距离 = 0.930）以及显著的曼特尔检验结果（P = 0.04）。 Tajima's D 值（-0.019，不显著）表明有效种群大小保持恒定。
我们得出结论，在遵循北美沙漠石膏矿床岛状分布模式的分化种群中，遗传漂变强烈而基因流较低。这些力量之间的相互作用可能促进物种形成事件，进而增加区域多样性，并可能解释与土壤限制相关的大量狭域特有物种。
