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Biogeography of succulent spurges from Brazilian Seasonally Dry Tropical Forest (SDTF)
TAXON ( IF 3.4 ) Pub Date : 2020-12-31 , DOI: 10.1002/tax.12423
Fernanda Hurbath 1 , Rebecca L. Stubbs 2 , Inês Cordeiro 3 , Nico Cellinese 4
Affiliation  

Seasonally Dry Tropical Forests (SDTFs) are found scattered throughout the Neotropics, from northwestern Mexico to northern Argentina, and southwestern and eastern Brazil, with eastern Brazil having the largest and most isolated fragment of SDTF, known as Caatinga. Growing knowledge from dated phylogenies and ancestral reconstruction studies suggests that SDTF lineages are nested in geographically structured phylogenies with clades highly restricted to each disjunct patch. To address these hypotheses, we investigated the biogeographic history of Euphorbia sect. Brasilienses, a group of succulent spurges from eastern Brazil's SDTF. To this aim, we assembled a concatenated matrix from 126 accessions with four markers (302 sequences from previous studies and 19 newly generated): one nuclear (ITS1) and three plastid (matK, ndhF, trnL‐trnF) loci. Our results showed that clade Brasilienses and its sister group Stachydium diverged from a common ancestor during the Miocene around 16.5 Ma. Clade Stachydium was recovered with a mean crown age of 7.7 Ma, while clade Brasilienses was recovered as a relatively young group that started diversifying about 3.1 Ma. Biogeographic results showed that the ancestral range of the clade Stachydium + Brasilienses comprised the Andes and eastern Brazil's SDTF, therefore suggesting past connections between western and eastern South America. The ancestral range of clade Brasilienses was restricted to eastern Brazil SDTF, which contrasts with clade Stachydium, which was recovered with a broader ancestral range around Late Miocene. Our results suggest limited dispersal abilities, niche conservatisms and an origin for E. sect. Brasilienses pre‐dating the Pleistocene. By contributing to the understanding of the origin and diversification of this group of endemic spurges, our study provides insights into the history of this SDTF in eastern South America.

中文翻译:

巴西季节性干旱热带森林(SDTF)的多肉植物大片的生物地理学

从墨西哥西北部到阿根廷北部,再到巴西西南部和东部,整个新热带地区都发现了季节性干热带森林(SDTF),其中巴西东部的SDTF片段最大,也是最孤立的,称为Caatinga。来自过时的系统发育史和祖先重建研究的不断增长的知识表明,SDTF谱系嵌套在地理结构上的系统发育史中,进化枝高度限制于每个分离的斑块。为了解决这些假设,我们调查了大戟属的生物地理历史。巴西菜,一群来自巴西东部SDTF的肉质植物。为此,我们从126个种质中组合了一个带有四个标记(先前研究的302个序列和19个新生成的)的连接矩阵:一个核(ITS1)和三个质体(matKndhFtrnL-trnF)的基因座。我们的结果表明,在中新世16.5 Ma左右,Brasilienses进化枝及其姊妹群Stachydium从一个共同的祖先开始分化。进化枝水生金冠的平均冠龄为7.7 Ma,而Brasilienses进化枝是一个相对年轻的群体,开始向3.1 Ma多样化。生物地理学结果表明,进化枝Stachydium + Brasilienses的祖先范围包括安第斯山脉和巴西东部的SDTF,因此暗示了南美西部和东部之间的过去联系。Brasilienses进化枝的祖先范围仅限于巴西东部SDTF,而Stachydium进化枝则相反,后者在中新世晚期以较宽的祖传范围被恢复。我们的结果表明有限的分散能力,利基保守性和E的起源教派。巴西利亚早于更新世。通过促进对这批地方性大流行的起源和多样化的理解,我们的研究提供了对这一南美南部SDTF历史的深刻见解。
更新日期:2021-02-21
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