Department of Biological Sciences and Museum of Natural Science, Louisiana State University, Baton Rouge, LA, USA.
Centro de Ornitología y Biodiversidad, Lima, Peru.
Evolution. 2024 Jan 4;78(1):53-68. doi: 10.1093/evolut/qpad187.
Rivers frequently delimit the geographic ranges of species in the Amazon Basin. These rivers also define the boundaries between genetic clusters within many species, yet river boundaries have been documented to break down in headwater regions where rivers are narrower. To explore the evolutionary implications of headwater contact zones in Amazonia, we examined genetic variation in the Blue-capped Manakin (Lepidothrix coronata), a species previously shown to contain several genetically and phenotypically distinct populations across the western Amazon Basin. We collected restriction site-associated DNA sequence data (RADcap) for 706 individuals and found that spatial patterns of genetic structure indicate several rivers, particularly the Amazon and Ucayali, are dispersal barriers for L. coronata. We also found evidence that genetic connectivity is elevated across several headwater regions, highlighting the importance of headwater gene flow for models of Amazonian diversification. The headwater region of the Ucayali River provided a notable exception to findings of headwater gene flow by harboring non-admixed populations of L. coronata on opposite sides of a < 1-km-wide river channel with a known dynamic history, suggesting that additional prezygotic barriers may be limiting gene flow in this region.
河流经常划定亚马逊流域物种的地理范围。这些河流也定义了许多物种内部遗传群之间的边界，但已有记录表明，在河流较窄的源头地区，这些边界会被打破。为了探索亚马逊地区源头接触区的进化意义，我们研究了蓝顶山雀（Lepidothrix coronata）的遗传变异，该物种先前在整个亚马逊西部流域被发现包含几个在遗传和表型上明显不同的种群。我们收集了 706 个个体的限制位点相关 DNA 序列数据（RADcap），发现遗传结构的空间模式表明，几条河流，特别是亚马逊河和乌卡亚利河，是 L. coronata 的扩散障碍。我们还发现证据表明，几个源头地区的遗传连通性有所提高，这突显了源头基因流对亚马逊多样化模型的重要性。乌卡亚利河的源头地区提供了一个值得注意的例外，在一条已知具有动态历史的<1 公里宽的河道两岸，发现了非混合的 L. coronata 种群，这表明该地区可能存在额外的合子前障碍限制基因流。
