Instituto de Investigación en Recursos Cinegéticos, CSIC-UCLM, E-13005 Ciudad Real, Spain.
Mol Phylogenet Evol. 2011 Dec;61(3):671-6. doi: 10.1016/j.ympev.2011.07.017. Epub 2011 Aug 3.
In response to climate changes that have occurred during Pleistocene glacial cycles, taxa associated to steppe vegetation might have followed a pattern of historical evolution in which isolation and fragmentation of populations occurred during the short interglacials and expansion events occurred during the long glacial periods, in contrast to the pattern described for temperate species. Here, we use molecular genetic data to evaluate this idea in a steppe bird with Palaearctic distribution, the little bustard (Tetrax tetrax). Overall, extremely low genetic diversity and differentiation was observed among eight little bustard populations distributed in Spain and France. Mismatch distribution analyses showed that most little bustard populations expanded during cooling periods previous to, and just after, the last interglacial period (127,000-111,000 years before present), when steppe habitats were widespread across Europe. Coalescent-based methods suggested that glacial expansions have resulted in substantial admixture in Western Europe due to the existence of different interglacial refugia. Our results are consistent with a model of evolution and genetic consequences of Pleistocene cycles with low between-population genetic differentiation as a result of short-term isolation periods during interglacials and long-term exchange during glacial periods.
针对更新世冰期循环中发生的气候变化，与草原植被相关的分类单元可能遵循历史进化模式，即在短暂的间冰期发生种群隔离和碎片化，而在漫长的冰期发生扩张事件，这与温带物种的模式描述相反。在这里，我们使用分子遗传数据来评估这种模式在具有古北界分布的草原鸟类——小鸨（Tetrax tetrax）中的适用性。总体而言，分布在西班牙和法国的 8 个小鸨种群表现出极低的遗传多样性和分化。不匹配分布分析表明，大多数小鸨种群在末次间冰期之前和之后的冷却时期扩张，当时草原栖息地广泛分布于整个欧洲。基于合并的方法表明，由于存在不同的间冰期避难所，冰川扩张导致西欧发生了大量的混合。我们的结果与一个进化模型一致，该模型认为，由于间冰期的短期隔离和冰期的长期交换，更新世循环导致种群间遗传分化较低，从而产生了遗传后果。
