The evolution of fire-dependent flowering in goldenasters (Pityopsis spp.)
The evolution of fire-dependent flowering in goldenasters (Pityopsis spp.)
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DOI：
10.3159/1095-5674(2005)132
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发表时间：
2005-07-01
影响因子：
0.3
通讯作者：
Brewer, JS
中科院分区：
文献类型：
--
作者：
Gowe, AK;Brewer, JS
戈韦K.和J.S. BREWER（Department of Biology，University of密西西比，University，密西西比，38677），The evolution of fire dependent flowing in goldenasters（Pityopsis spp.），J. Torrey Bot. Soc·132：384-400. 2005.-虽然规定的火被认为是有利于火适应物种，明确的证据存在的火适应物种是缺乏在许多系统。我们提出了一个比较生态学研究的结果，火依赖开花的属Pityopsis（菊科）。我们根据已发表的形态学数据构建了该属的植物发生学，然后在由此产生的拓扑结构上绘制了依赖于火的开花。我们研究了花卉诱导，树木和地被树冠覆盖，和定居火灾频率在每个物种的首选栖息地之间的关系。研究结果支持以下假设：1）火依赖开花发生在一个属下分类群中（组Graminifoliae），但不是在其他（Pityopsis组）; 2）在无火年份，依赖火的开花发生在包含密集地被树冠的生境或微型地点，在美国，火依赖型开花更可能发生在火和闪电频率相对较高的地区。系统发育分析表明，这两个组没有形成独立的单系群。此外，在以前的分类学处理中用于区分部分的特征（即在开花时存在的基生莲座丛）实际上可能等同于火依赖开花。我们假设，火依赖开花是一种形式的自适应表型可塑性，保留在禾本科部分，并允许利用各种不同的火灾易发稀树草原在美国东南部的波动的竞争环境。
GOWE, A. K. AND J. S. BREWER (Department of Biology, University of Mississippi, University, Mississippi, 38677), The evolution of fire-dependent flowering in goldenasters (Pityopsis spp.), J. Torrey Bot. Soc. 132: 384-400. 2005.-Although prescribed fire is thought to benefit fire-adapted species, unequivocal evidence for the existence of fire-adapted species is lacking in many systems. We present the results of a comparative ecological study of fire-dependent flowering in the genus Pityopsis (Asteraceae). We constructed a phylogeny of the genus based on published morphological data and then mapped fire-dependent flowering on the resulting topology. We examined relationships between floral induction, tree and groundcover canopy coverage, and presettlement fire frequency within each species' preferred habitat. Results of our investigations supported the following hypotheses: 1) Fire-dependent flowering occurred in one infrageneric taxonomic group (sect. Graminifoliae) but not in the other (sect. Pityopsis); 2) Fire-dependent flowering occurred in habitats or microsites that contained a dense groundcover canopy during years without fire, and 3) Fire-dependent flowering was more likely to occur in areas of relatively high fire and lightning frequency in the United States. The phylogenetic analysis suggested that the two sections of Pityopsis did not form separate monophyletic groups. Furthermore, the character used to distinguish sections in previous taxonomic treatments (i.e. basal rosette present at the time of flowering) may, in fact, be equivalent to fire-dependent flowering. We hypothesize that fire-dependent flowering is a form of adaptive phenotypic plasticity that was retained in the Graminifoliae section and permitted exploitation of a fluctuating competitive environment within a variety of different fire-prone savannas in the southeastern United States.