Helmholtz AI, Helmholtz Munich, Neuherberg, Germany.
Helmholtz Pioneer Campus, Helmholtz Munich, Neuherberg, Germany.
PLoS Biol. 2024 Sep 10;22(9):e3002755. doi: 10.1371/journal.pbio.3002755. eCollection 2024 Sep.
The information contained in population genomic data can tell us much about the past ecology and evolution of species. We leveraged detailed phenotypic and genomic data of nearly all living kākāpō to understand the evolution of its feather color polymorphism. The kākāpō is an endangered and culturally significant parrot endemic to Aotearoa New Zealand, and the green and olive feather colorations are present at similar frequencies in the population. The presence of such a neatly balanced color polymorphism is remarkable because the entire population currently numbers less than 250 birds, which means it has been exposed to severe genetic drift. We dissected the color phenotype, demonstrating that the two colors differ in their light reflectance patterns due to differential feather structure. We used quantitative genomics methods to identify two genetic variants whose epistatic interaction can fully explain the species' color phenotype. Our genomic forward simulations show that balancing selection might have been pivotal to establish the polymorphism in the ancestrally large population, and to maintain it during population declines that involved a severe bottleneck. We hypothesize that an extinct apex predator was the likely agent of balancing selection, making the color polymorphism in the kākāpō a "ghost of selection past."
群体基因组数据中包含的信息可以让我们深入了解物种过去的生态和进化。我们利用几乎所有现存鸮鹦鹉的详细表型和基因组数据，来了解其羽毛颜色多态性的进化。鸮鹦鹉是新西兰特有的一种濒危且具有文化意义的鹦鹉，其绿色和橄榄色羽毛颜色在种群中出现的频率相似。这种如此完美平衡的颜色多态性现象引人注目，因为目前整个种群的数量不到 250 只，这意味着它已经经历了严重的遗传漂变。我们对颜色表型进行了剖析，结果表明，两种颜色的光反射模式存在差异，这是由于羽毛结构的不同造成的。我们使用定量基因组学方法鉴定出两个遗传变异，它们的上位性相互作用可以完全解释该物种的颜色表型。我们的基因组正向模拟表明，平衡选择可能是在祖先较大的种群中建立多态性的关键因素，并在经历严重瓶颈的种群衰退期间维持多态性。我们假设，一种已灭绝的顶级捕食者可能是平衡选择的原因，使得鸮鹦鹉的颜色多态性成为“过去选择的幽灵”。
