Amount of introgression in flycatcher hybrid zones reflects regional differences in pre and post-zygotic barriers to gene exchange
Amount of introgression in flycatcher hybrid zones reflects regional differences in pre and post-zygotic barriers to gene exchange
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DOI：
10.1111/j.1420-9101.2005.00964.x
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发表时间：
2005-11-01
影响因子：
2.1
通讯作者：
Sætre, GP
中科院分区：
文献类型：
--
作者：
Borge, T;Lindroos, K;Sætre, GP
基因渗入是指一个物种或半物种的等位基因通过杂交和回交进入另一个物种或半物种的基因库。这种情况发生的频率取决于杂交的频率以及与“纯”个体相比杂交和回交的适合度。在中欧和瑞典东海岸的哥特兰岛和奥兰岛的一个临床杂交区，有领捕蝇蝇（Ficedula albicollis）和斑捕蝇蝇（F. hypoleuca）共存并以低至中等频率杂交。有关孵化成功率的数据表明，与岛屿相比，中欧的杂交后代繁殖能力较差。使用分子标记来推断亲子关系的直接适应度估计与人口统计数据一致。通过对基因型种间替换和单核苷酸多态性的标记阵列微序列分析，我们发现，在两个岛屿种群（哥特兰岛和奥兰岛）中，斑蝇向有领捕蝇的基因渗透量高于中欧杂交区（捷克共和国和匈牙利）两个地理上截然不同的地区。在所有地区，从有领飞禽到有斑飞禽的渗入量都很低或似乎没有。不同的渗进模式与杂交率和杂交适应度的区域差异是一致的。我们认为，基因交流的障碍可能在一定程度上被打破了，因为来自异族的不对称基因流动。另外，在中欧，由于影响合子前和合子后分离的基因在这些鸟类中都是性别连锁的，因此更明显的强化合子前分离可能通过搭便车增加了合子后分离。我们的一个遗传标记似乎以比其他标记高得多的速度从花斑飞禽进化到有领飞禽。我们讨论了在新的遗传背景下，渐渗标记可能与正选择下的基因有关的可能性。
Introgression is the incorporation of alleles from one species or semispecies into the gene pool of another through hybridization and backcrossing. The rate at which this occurs depends on the frequency of hybridization and the fitness of hybrids and backcrosses compared to 'pure' individuals. The collared flycatcher (Ficedula albicollis) and the pied flycatcher (F. hypoleuca) co-exist and hybridize at low to moderate frequencies in a clinal hybrid zone in Central Europe and on the islands of Gotland and Oland off the Swedish east coast. Data on hatching success suggest that hybrids are less fertile in Central Europe compared to on the islands. Direct fitness estimates using molecular markers to infer paternity are consistent with the demographic data. Applying a tag-array-based minisequencing assay to genotype interspecific substitutions and single nucleotide polymorphisms we demonstrate that the amount of introgression from the pied to the collared flycatcher is higher in the two island populations (Gotland and Oland) than in two geographically distinct areas from the Central European hybrid zone (Czech Republic and Hungary). In all areas the amount of introgression from collared to pied flycatchers is very low or seemingly absent. The different patterns of introgression are consistent with regional differences in rates of hybridization and fitness of hybrids. We suggest that barriers to gene exchange may have been partly broken down on the islands due to asymmetric gene flow from allopatry. Alternatively, or in addition, more pronounced reinforcement of prezygotic isolation in Central Europe might have increased post-zygotic isolation through hitchhiking, since genes affecting pre and post-zygotic isolation are both sex-linked in these birds. One of our genetic markers appears to introgress from pied to collared flycatchers at a much higher rate than the other markers. We discuss the possibility that the introgressed marker may be linked to a gene which is under positive selection in the novel genetic background.