Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
Department of Biological Sciences, Humboldt State University, Arcata, CA, 95521, USA.
New Phytol. 2021 Dec;232(6):2520-2534. doi: 10.1111/nph.17675. Epub 2021 Sep 12.
Admixture is a mechanism by which species of long-lived plants may acquire novel alleles. However, the potential role of admixture in the origin and maintenance of tropical plant diversity is unclear. We ask whether admixture occurs in an ecologically important clade of Eschweilera (Parvifolia clade, Lecythidaceae), which includes some of the most widespread and abundant tree species in Amazonian forests. Using target capture sequencing, we conducted a detailed phylogenomic investigation of 33 species in the Parvifolia clade and investigated specific hypotheses of admixture within a robust phylogenetic framework. We found strong evidence of admixture among three ecologically dominant species, E. coriacea, E. wachenheimii and E. parviflora, but a lack of evidence for admixture among other lineages. Accepted species were largely distinguishable from one another, as was geographic structure within species. We show that hybridization may play a role in the evolution of the most widespread and ecologically variable Amazonian tree species. While admixture occurs among some species of Eschweilera, it has not led to widespread erosion of most species' genetic or morphological identities. Therefore, current morphological based species circumscriptions appear to provide a useful characterization of the clade's lineage diversity.
杂种形成是一种机制，通过该机制，长寿命植物的物种可能获得新的等位基因。然而，杂种形成在热带植物多样性的起源和维持中的潜在作用尚不清楚。我们询问杂种形成是否发生在生态重要的 Eschweilera 进化枝（Parvifolia 进化枝，豆科）中，该进化枝包括亚马逊森林中一些分布最广和最丰富的树种。使用目标捕获测序，我们对 Parvifolia 进化枝中的 33 个物种进行了详细的系统基因组学调查，并在稳健的系统发育框架内调查了杂种形成的具体假设。我们发现，在三个生态优势种（E. coriacea、E. wachenheimii 和 E. parviflora）之间存在强烈的杂种形成证据，但在其他谱系之间没有杂种形成的证据。被接受的物种彼此之间有很大的区别，物种内的地理结构也是如此。我们表明，杂交可能在最广泛和生态变化最大的亚马逊树种的进化中发挥作用。虽然 Eschweilera 的一些物种之间存在杂种形成，但它并没有导致大多数物种的遗传或形态特征的广泛侵蚀。因此，目前基于形态的物种划分类似为该进化枝的谱系多样性提供了有用的特征描述。
