Folk Ryan A, Freudenstein John V
Herbarium, Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, 1315 Kinnear Road, Columbus, Ohio 43212 USA.
Am J Bot. 2014 Sep;101(9):1532-50. doi: 10.3732/ajb.1400290. Epub 2014 Sep 21.
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The use of multiple genetic regions from the nuclear genome, including low-copy markers, has long been recognized as essential to robust phylogenetic construction, addressing gene tree incongruence, and allowing increased resolution to test current taxonomy and resolve basic hypotheses about character evolution, biogeography, and other organismal traits of interest to biologists. Heuchera, the largest genus of Saxifragaceae endemic to North America, has presented an unusually difficult case for systematists with limited sampling in previous molecular studies. We used morphological and multilocus molecular phylogenetic data to test the monophyly of Heuchera, better resolve hypotheses of relationships, and test hypotheses of character evolution, biogeography, and diversification rates.•
Phylogenetic relationships were inferred using sequences from six nuclear loci and 39 morphological characters using concatenation and coalescent analysis. Ancestral state reconstruction, diversification, and correlated evolution of morphological traits were performed using parsimony, BiSSE, and Pagel's method, respectively.•
The concatenation and species tree analyses gave confident support to the monophyly of Heuchera and suggested several well-supported subclades. The addition of morphological data significantly improved support numbers. Ancestral character reconstruction suggested frequent homoplasy and reversal of floral characters and a complex biogeographical history.•
Heuchera is a natural genus; however, the current subgeneric classification is artificial and requires revision. Biogeographic reconstructions suggest a Pacific Northwest origin for the genus; morphological shifts in stamen exsertion and hypanthium length are hypothesized to have driven diversification in Heuchera in concert with possible pollinator shifts.
长期以来，使用来自核基因组的多个遗传区域，包括低拷贝标记，对于稳健的系统发育构建、解决基因树不一致问题以及提高分辨率以检验当前分类法和解决有关特征进化、生物地理学以及生物学家感兴趣的其他生物体特征的基本假设至关重要。矾根属是北美特有的虎耳草科中最大的属，在以往的分子研究中，由于取样有限，给系统学家带来了异常困难的情况。我们使用形态学和多位点分子系统发育数据来检验矾根属的单系性，更好地解析亲缘关系假设，并检验特征进化、生物地理学和多样化速率的假设。
使用来自六个核基因座的序列和39个形态特征，通过串联和合并分析推断系统发育关系。分别使用简约法、BiSSE和佩格尔方法进行祖先状态重建、多样化分析以及形态特征的相关进化分析。
串联分析和物种树分析为矾根属的单系性提供了可靠支持，并表明了几个得到充分支持的亚分支。添加形态学数据显著提高了支持率。祖先特征重建表明花部特征频繁出现同塑性和逆转，以及复杂的生物地理历史。
矾根属是一个自然属；然而，当前的亚属分类是人为的，需要修订。生物地理重建表明该属起源于太平洋西北部；推测雄蕊伸出和托杯长度的形态变化与可能的传粉者转变共同推动了矾根属的多样化。
