Arntzen Jan W, Trujillo Tania, Butôt Roland, Vrieling Klaas, Schaap Onno, Gutiérrez-Rodríguez Jorge, Martínez-Solano Iñigo
Naturalis Biodiversity Center, P.O. Box 9517, Leiden, 2300 RA The Netherlands.
Museo Nacional de Ciencias Naturales, CSIC, c/José Gutiérrez Abascal, 2, Madrid, 28006 Spain.
Front Zool. 2016 Dec 19;13:52. doi: 10.1186/s12983-016-0184-7. eCollection 2016.
Hybrid zones are regions where individuals of two species meet and produce hybrid progeny, and are often regarded as natural laboratories to understand the process of species formation. Two microevolutionary processes can take place in hybrid zones, with opposing effects on population differentiation. Hybridization tends to produce genetic homogenization, reducing species differences, whereas the presence of mechanisms of reproductive isolation result in barriers to gene flow, maintaining or increasing differences between taxa.
Here we study a contact zone between two hybridizing toad species, and , through a combination of molecular (12 polymorphic microsatellites, four nuclear and two mitochondrial SNP markers) and morphological data in a transect in the northwest of France. The results show largely concordant clines across markers, defining a narrow hybrid zone of ca. 30 km wide. Most hybrids in the centre of the contact zone are classified as F or backcrossed individuals, with no individuals assigned to the F hybrid class.
We discuss the implications of these results for our understanding of the evolutionary history of these species. We anticipate that the toad contact zone here described will become an important asset in the study of hybrid zone dynamics and evolutionary biology because of its easy access and the abundance of the species involved.
杂交带是两个物种的个体相遇并产生杂交后代的区域，常被视为理解物种形成过程的天然实验室。在杂交带可能发生两种微观进化过程，它们对种群分化有着相反的影响。杂交倾向于产生基因同质化，减少物种差异，而生殖隔离机制的存在则导致基因流动障碍，维持或增加分类单元之间的差异。
在这里，我们通过结合分子数据（12个多态微卫星、4个核单核苷酸多态性标记和2个线粒体单核苷酸多态性标记）和形态学数据，对法国西北部一个样带中两种杂交蟾蜍物种—— 和 之间的接触带进行了研究。结果显示，各标记的渐变群在很大程度上是一致的，确定了一个约30公里宽的狭窄杂交带。接触带中心的大多数杂种被归类为F1或回交个体，没有个体被归为F2杂种类别。
我们讨论了这些结果对我们理解这些物种进化历史的意义。我们预计，这里描述的蟾蜍接触带将因其易于进入和所涉及物种的丰富性，成为杂交带动态和进化生物学研究的重要资源。
