|
![[優(yōu)秀文章推薦] 中科院解析溫帶竹子分支系統(tǒng)發(fā)育關(guān)系]()
Tree resolution increases as data are added to the phylogenetic analysis.
溫帶竹子分支(the temperate bamboo clade)包括23-32屬,約546種,主要分布于東亞地區(qū)(特別是喜馬拉雅)和東南亞地區(qū),少數(shù)種類分布到印度南部和斯里蘭卡、非洲和馬達(dá)加斯加,以及北美洲東部的低海拔地區(qū)和熱帶或亞熱帶高山。東亞有該分支近500種,是其多樣化中心,中國西南特有種有180余種。溫帶竹子分支在分子系統(tǒng)學(xué)研究中被證明是一個單系類群,但類群內(nèi)部之間的關(guān)系尚未得到澄清。中國科學(xué)院昆明植物研究所李德銖研究團(tuán)隊致力于溫帶竹類的分類和系統(tǒng)發(fā)育研究,在大量材料收集的基礎(chǔ)上,基于8個葉綠體DNA片段的分析將溫帶竹類劃分為10個主要支系;基于葉綠體DNA和核DNA片段的分析,發(fā)現(xiàn)第11個支系和第12個支系;基于葉綠體全基因組數(shù)據(jù),對這些支系間的系統(tǒng)關(guān)系進(jìn)行了探索,澄清了大部分支系間的關(guān)系,但這些主要支系內(nèi)部的關(guān)系無法通過相對保守的葉綠體基因組序列來解決,而需要更多的核基因數(shù)據(jù)。
![[優(yōu)秀文章推薦] 中科院解析溫帶竹子分支系統(tǒng)發(fā)育關(guān)系-1]()
Phylogeny of the temperate bamboos based on an ML analysis
近日,昆明植物所科研人員利用一種簡化基因組測序的方法即RAD (restriction-site-associated DNA) 測序方法,在全基因組水平開發(fā)大量的SNPs標(biāo)記,對第五分支(Phyllostachys clade)及其相關(guān)支系(Shibataea, and Arundinaria clades)的系統(tǒng)發(fā)育關(guān)系進(jìn)行了研究;赗AD測序數(shù)據(jù)所獲得的SNP矩陣,構(gòu)建了目前為止竹亞科分辨率最高的一棵系統(tǒng)發(fā)育樹,并得到8個主要的分支:Yushania + Fargesia,Chimonocalamus + Fargesia sect. Ampullares, alpine Bashania+Fargesia, Drepanostachyum + Himalayacalamus, Gaoligongshania, Sino-Japanese clade, Chimonobambusa, Ferrocalamus + Indocalamus。結(jié)果表明,基于葉綠體片段所命名的第五分支(Phyllostachys clade),第四(Shibataea clade)及第六分支(Arundinaria clade)均不為單系。與葉綠體片段所得到的結(jié)果不同的是,基于RAD數(shù)據(jù)的系統(tǒng)發(fā)育關(guān)系與按照形態(tài)性狀的傳統(tǒng)分類結(jié)果較一致。具有細(xì)型地下莖的物種形成了兩個單系分支,一支為主要分布于東亞低海拔地區(qū)的Sino-Japanese clade,另一支為特有分布于橫斷山-喜馬拉雅高海拔地區(qū)的alpine Bashania。此外,研究對比了兩種不同SNP生成的方法,基于參考序列比對的BWA-GATK方法,以及基于de novo組裝的Stacks方法。盡管有大量缺失數(shù)據(jù)的存在,基于兩種方法所得到的最大矩陣,均能獲得拓?fù)浣Y(jié)構(gòu)相似及高分辨率的系統(tǒng)發(fā)育樹。該研究對于揭示溫帶竹類的起源與演化具有科學(xué)意義,對進(jìn)一步研究該類群物種多樣性的形成和演化歷史打下了堅實基礎(chǔ)。
The temperate bamboos (tribe Arundinarieae, Poaceae) are strongly supported as monophyly in recent molecular studies, but taxonomic delineation and phylogenetic relationships within the tribe lack resolution. Here, we sampled 39 species (36 temperate bamboos and 3 outgroups) for restriction-site associated DNA sequencing (RAD-seq) with an emphasis on Phyllostachys clade and related clades. Using the largest data matrix for the bamboos to date, we were able to infer phylogenetic relationships with unparalleled resolution. The Phyllostachys, Shibataea, and Arundinaria clades defined from plastid phylogeny, were not supported as monophyletic group. However, the RAD-seq phylogeny largely agreed with the morphology-based taxonomy, with two clades having leptomorph rhizomes strongly supported as monophyletic group. We also explored two approaches, BWA-GATK (a mapping system) and Stacks (a grouping system), for differences in SNP calling and phylogeny inference. For the same level of missing data, the BWA-GATK pipeline produced much more SNPs in comparison with Stacks. Phylogenetic analyses of the largest data matrices from both pipelines, using concatenation and coalescent methods provided similar tree topologies, despite the presence of missing data. Our study demonstrates the utility of RAD-seq data for elucidating phylogenetic relationships between genera and higher taxonomic levels in this important but phylogenetically challenging group. |