Quintanar-Castillo Angélica, Amorim Andre M, Pace Marcelo R
Posgrado en Ciencias Biológicas. Instituto de Biología, Universidad Nacional Autónoma de México, Circuito Zona Deportiva s.n. de Ciudad Universitaria, Coyoacán, Mexico City, 04510, Mexico.
Departamento de Botánica y Herbario Nacional de México, Instituto de Biología, Universidad Nacional Autónoma de México, Circuito Zona Deportiva s.n. de Ciudad Universitaria, Coyoacán, Mexico City, 04510, Mexico.
Am J Bot. 2025 Jun;112(6):e70056. doi: 10.1002/ajb2.70056. Epub 2025 Jun 16.
Within the Malpighiaceae, the Bunchosia clade is distinctive for its significant habit variation and abundance of different vascular variants. However, the processes underlying the diversification of the vascular system over time and the ontogenetic events involved remain unclear. Focusing on the Bunchosia clade, this study explores how new vascular configurations evolve in Malpighiaceae and the factors driving this diversification.
We analyzed stem ontogeny in 19 species representing all six genera of the Bunchosia clade, sampling from the apex to the base of the plants. We used the phytools package in R to map the entire stem ontogenies onto the most recent phylogeny estimate of Malpighiaceae, identifying the developmental modifications and processes involved in stem diversification within the clade.
The ancestral condition of the clade was inferred to be a lianescent habit with regular stem anatomy. Over evolutionary time, two independent transitions to a self-supporting habit were inferred to have occurred. We identified five ontogenetic pathways, which led to distinct vascular system arrangements. Additionally, we propose two new records of cambial variants for the family.
From a regular secondary growth condition, different vascular variants evolved in a short period of evolutionary time in this clade. The self-supporting habit appeared twice: (1) in Bunchosia, maintaining a plesiomorphic regular secondary growth, and (2) another in Echinopterys, where the self-supporting habit retained the vascular variant inherited from the ancestor of the subclade. Our study provides insights into how stem vasculature diversified in lianescent clades and how it is related to habit transitions.
在金虎尾科中，Bunchosia分支因其显著的习性变异和丰富多样的维管系统变体而独具特色。然而，随着时间推移维管系统多样化的潜在过程以及所涉及的个体发育事件仍不清楚。本研究聚焦于Bunchosia分支，探讨了金虎尾科中新的维管结构是如何演化的以及驱动这种多样化的因素。
我们分析了代表Bunchosia分支所有六个属的19个物种的茎个体发育，从植株顶端到基部进行采样。我们使用R语言中的phytools软件包将整个茎的个体发育过程映射到金虎尾科最新的系统发育估计树上，确定该分支内茎多样化所涉及的发育变化和过程。
推断该分支的祖先状态为具规则茎解剖结构的藤本习性。在进化过程中，推断发生了两次独立的向自支撑习性的转变。我们确定了五条个体发育途径，这些途径导致了不同的维管系统排列。此外，我们还提出了该科形成层变体的两个新记录。
从规则的次生生长状态出发，在这个分支中不同的维管变体在较短的进化时间内演化出来。自支撑习性出现了两次：（1）在Bunchosia中，保持了一个近祖的规则次生生长；（2）另一次出现在Echinopterys中，其自支撑习性保留了从亚分支祖先继承的维管变体。我们的研究为藤本分支中茎维管系统如何多样化以及它与习性转变如何相关提供了见解。
