Data from: Mode and tempo of sequence and floral evolution within the Anserineae

The Chenopodiaceae Tribe Anserineae Dumort was proposed to include the genus Spinacia and the genus Blitum. In addition to the recent domestication of Spinacia, the tribe demonstrates extensive evolution within its floral development. We test whether the development of dioecy, monoecy, and protogyny is reflected differentially among floral developmental versus non-floral developmental genes, and whether recent domestication leaves traces in the phylogenetic relationship within the genus Spinacia. The phylogenetic predictions consistently support the sister relationship of Spinacia sp. to a Blitum clade consisting of Blitum bonus-henricus, Blitum virgatum, and Blitum nuttallianum. Relative rates tests indicate a generally faster rate of nucleotide substitutions within Spinacia. Tests of selection indicate that there is generally purifying selection acting on the sequences. In addition, insertion/deletion (indel) events occur more prominently within the Spinacia clade and occur in both coding and intron regions. The phylogenetic relationships within this tribe calls into question the hypothesis that dioecy in Spinacia evolved from a monoecious grade. The evidence for purifying selection in Spinacia suggests that the increased nucleotide substitution rates are not driving protein evolution, in contrast to evidence of protein sequence and structure evolution driven by indels. There is no footprint of domestication on sequence evolution, and we cannot detect phylogenetic signals that would support separation of the Spinacia accessions into three distinct taxa.

藜科（Chenopodiaceae）雁形族（Anserineae Dumort）曾被提议包含菠菜属（Spinacia）与藜属（Blitum）两个属。除近期完成驯化的菠菜属物种外，该族在花发育进程中展现出广泛的演化特征。本研究旨在检验两项科学问题：其一，雌雄异株（dioecy）、雌雄同株（monoecy）与雌性先熟（protogyny）的发育性状，是否在花发育相关基因与非花发育相关基因间呈现差异化反映；其二，近期的驯化事件是否会在菠菜属内的系统发育关系中留下演化痕迹。系统发育预测结果一致支持菠菜属物种（Spinacia sp.）与由亨利藜（Blitum bonus-henricus）、细叶藜（Blitum virgatum）和纳特氏藜（Blitum nuttallianum）构成的藜属演化支互为姊妹群。相对速率检验结果显示，菠菜属内的核苷酸替换速率整体更快。选择压力检验表明，该类群的序列整体受到净化选择（purifying selection）作用。此外，插入/缺失（indel）事件在菠菜属演化支内更为频发，且同时发生于编码区与内含子区域。该族内的系统发育关系，对“菠菜属的雌雄异株性状源自雌雄同株演化阶段”这一假说提出了质疑。与由插入/缺失事件驱动的蛋白质序列及结构演化证据不同，菠菜属内的净化选择证据表明，升高的核苷酸替换速率并未推动蛋白质层面的演化。本研究未检测到驯化事件对序列演化留下的分子印记，同时无法找到足够的系统发育信号以支持将菠菜属种质划分为三个独立的类群。