Department of Biological Sciences, Macquarie University Sydney, NSW 2109, Australia.
Ecol Evol. 2012 Jun;2(6):1208-19. doi: 10.1002/ece3.259.
The effect of separation by biogeographic features followed by secondary contact can blur taxonomic boundaries and produce complex genetic signatures. We analyzed population structure and gene flow across the range of the long-tailed finch (Poephila acuticauda) in northern Australia (1) to test the hypothesis that Ord Arid Intrusion acted as the causative barrier that led to divergence of P. acuticauda subspecies, (2) to determine whether genetic data support the presence of a gradual cline across the range or a sudden shift, both of which have been suggested based on morphological data, and (3) to estimate levels of contemporary gene flow within this species complex. We collected samples from 302 individuals from 10 localities. Analyses of 12 microsatellite loci and sequence data from 333 base pairs of the mitochondrial control region were used to estimate population structure and gene flow, using analysis of molecular variance (AMOVA), haplotype network analysis, frequency statistics, and clustering methods. Mitochondrial sequence data indicated the presence of three genetic groups (regions) across the range of P. acuticauda. Genetic diversity was highest in the east and lowest in the west. The Ord Arid Intrusion appears to have functioned as a biogeographic barrier in the past, according to mtDNA evidence presented here and evidence from previous studies. The absence of isolation by distance between adjacent regions and the lack of population genetic structure of mtDNA within regions indicates that genetic changes across the range of P. acuticauda subspecies are characterized by discrete breaks between regions. While microsatellite data indicate a complete absence of genetic structure across this species' range, it appears unlikely that this results from high levels of gene flow. Mitochondrial data do not support the presence of contemporary gene flow across the range of this species.
地理隔离和随后的二次接触的影响可能会模糊分类学边界，并产生复杂的遗传特征。我们分析了长尾雀（Poephila acuticauda）在澳大利亚北部的种群结构和基因流动，以检验以下假设：Ord 干旱侵入曾是导致长尾雀亚种分歧的原因，（2）确定遗传数据是否支持形态学数据所提出的渐变群还是突然转变，（3）估计该物种复杂体内当代基因流动的水平。我们从 10 个地点收集了 302 个人的样本。使用分子方差分析（AMOVA）、单倍型网络分析、频率统计和聚类方法，分析了 12 个微卫星基因座和线粒体控制区 333 个碱基对的序列数据，以估计种群结构和基因流动。线粒体序列数据表明，长尾雀的分布范围内存在三个遗传群体（区域）。东部的遗传多样性最高，西部的最低。根据这里提供的线粒体证据和先前研究的证据，奥尔德干旱侵入过去似乎是一个地理障碍。在相邻区域之间没有距离隔离，并且区域内的 mtDNA 没有种群遗传结构，这表明长尾雀亚种分布范围内的遗传变化的特征是区域之间的离散断裂。虽然微卫星数据表明该物种的整个分布范围内完全没有遗传结构，但这似乎不太可能是由于高水平的基因流动所致。线粒体数据不支持该物种的分布范围内存在当代基因流动。
