Genetic admixture despite ecological segregation in a North African sparrow hybrid zone (Aves, Passeriformes, Passer domesticus x Passer hispaniolensis)

Under different environmental conditions hybridization between the same species might result in different patterns of genetic admixture. Particularly, species pairs with large distribution ranges and long evolutionary history may have experienced several independent hybridization events over time in different zones of overlap. In birds, the diverse hybrid populations of the house sparrow (Passer domesticus) and the Spanish sparrow (P. hispaniolensis) provide a striking example. Throughout their range of sympatry, these two species do not regularly interbreed, however a stabilized hybrid form (P. italiae) exists on the Italian Peninsula and on several Mediterranean islands. The spatial distribution pattern on the Eurasian continent strongly contrasts the situation in North Africa, where house sparrows and Spanish sparrows occur in close vicinity of phenotypically intermediate populations across a broad mosaic hybrid zone. In this study, we investigate patterns of divergence and admixture...在不同环境条件下，同一物种间的杂交可产生各异的遗传混合（genetic admixture）模式。尤其值得注意的是，拥有广泛分布范围与悠久演化历史的物种类群，可能在不同的重叠分布区内先后经历多次独立的杂交事件。 在鸟类类群中，家麻雀（Passer domesticus）与西班牙麻雀（P. hispaniolensis）多样的杂交种群便是极具代表性的案例。在二者的同域分布范围内，这两个物种通常不会进行常规种间杂交，但在意大利半岛及若干地中海岛屿上，却存在一种稳定的杂交型（P. italiae）。 欧亚大陆的空间分布格局与北非的情况形成强烈反差：在北非，家麻雀与西班牙麻雀在广阔的镶嵌杂交带中彼此邻近分布，同时存在表型介于二者之间的种群。本研究旨在探究物种分化与遗传混合的模式……