Benítez-Benítez Carmen, Otero Ana, Ford Kerry A, García-Moro Pablo, Donadío Sabina, Luceño Modesto, Martín-Bravo Santiago, Jiménez-Mejías Pedro
Botany Area, Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, Seville, Spain.
Grainger Bioinformatics Center, Department of Science and Education, The Field Museum, Chicago, IL, United States.
Front Plant Sci. 2021 Nov 8;12:735302. doi: 10.3389/fpls.2021.735302. eCollection 2021.
subgenus is an engaging study group due to its early diversification compared to most lineages, and its remarkable disjunct distribution in four continents corresponding to three independent sections: sect. in Western Palearctic, sect. in Afrotropical region, and sect. in South America (SA) and SW Pacific. The latter section is mainly distributed in Patagonia and the Andes, where it is one of the few groups with a significant diversification. We assess the role of historical geo-climatic events in the evolutionary history of the group, particularly intercontinental colonization events and diversification processes, with an emphasis on SA. We performed an integrative study using phylogenetic (four DNA regions), divergence times, diversification rates, biogeographic reconstruction, and bioclimatic niche evolution analyses. The crown age of subg. (early Miocene) supports this lineage as one of the oldest within . The diversification rate probably decreased over time in the whole subgenus. Geography seems to have played a primary role in the diversification of subg. . Inferred divergence times imply a diversification scenario away from primary Gondwanan vicariance hypotheses and suggest long-distance dispersal-mediated allopatric diversification. Section remained in Northern Patagonia since its divergence until Plio-Pleistocene glaciations. Andean orogeny appears to have acted as a northward corridor, which contrasts with the general pattern of North-to-South migration for temperate-adapted organisms. A striking niche conservatism characterizes the evolution of this section. Colonization of the SW Pacific took place on a single long-distance dispersal event from SA. The little ecological changes involved in the trans-Pacific disjunction imply the preadaptation of the group prior to the colonization of the SW Pacific. The high species number of the section results from simple accumulation of morphological changes (disparification), rather than shifts in ecological niche related to increased diversification rates (radiation).
亚属是一个引人关注的研究类群，因为与大多数谱系相比，它分化较早，且在四大洲呈现出显著的间断分布，对应三个独立的组：西古北区的组、热带非洲地区的组，以及南美洲（SA）和西南太平洋的组。后一组主要分布在巴塔哥尼亚和安第斯山脉，是少数具有显著多样化的类群之一。我们评估了历史地理气候事件在该类群进化历史中的作用，特别是洲际殖民事件和多样化过程，重点关注南美洲。我们进行了一项综合研究，运用系统发育分析（四个DNA区域）、分歧时间、多样化速率、生物地理重建以及生物气候生态位演化分析。亚属的冠群年龄（中新世早期）支持该谱系是内最古老的谱系之一。整个亚属的多样化速率可能随时间下降。地理因素似乎在亚属的多样化过程中起了主要作用。推断出的分歧时间意味着一种多样化模式，背离了主要的冈瓦纳大陆间断分布假说，并表明是由远距离扩散介导的异域多样化。组自分化以来一直留在巴塔哥尼亚北部，直到上新世 - 更新世冰川期。安第斯造山运动似乎起到了向北的走廊作用，这与适应温带生物的南北迁移一般模式形成对比。该组的演化具有显著的生态位保守性。西南太平洋的殖民是通过从南美洲的一次远距离扩散事件发生的。跨太平洋间断分布所涉及的生态变化很小，这意味着该类群在殖民西南太平洋之前就已经预先适应了。该组的物种数量多是形态变化（分化）简单积累的结果，而非与多样化速率增加（辐射）相关的生态位转变。
