Why should we investigate the morphological disparity of plant clades?
Why should we investigate the morphological disparity of plant clades?
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为什么我们应该研究植物进化枝的形态差异？
DOI：
10.1093/aob/mcv135
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发表时间：
2016
期刊：
影响因子：
4.2
通讯作者：
Oyston JW
中科院分区：
文献类型：
--
作者：
Oyston JW
背景异质性是指类群样本的形态变异，有别于多样性或分类丰富度。多样性和差异从根本上是脱钩的；许多群体在其进化的早期就达到了高度的差异，而多样性仍然相对较低。随后，即使面对静态或不断缩小的差距，多样性也可能通过对形态设计空间(形态空间)的日益精细的细分而增加。许多动物分支在进化的早期就达到了高度的差异，但对植物分支的可比研究很少，尽管它们在生态和进化上具有深远的重要性。这项研究提供了一些前瞻性的和一些初步的宏观进化分析。方法经典形态计量学方法最适用于形式上的合理保存，但在形态差异变大时失去吸引力(例如，在较高分类群之间的比较中)。离散字符矩阵提供了一种比较多种形式的方法。这项研究探索了来自8个离散数据集的主要植物分支的形态空间，并讨论了它们的宏观进化含义。关键结果本研究中的大多数植物分支显示出最初的高度差异，接近或达到后来达到的最大水平。这些植物分支的特征是进化的初始阶段，在此期间，其经验形态空间的大部分区域被殖民。被子植物、棕榈树、松树和蕨类植物的差异随时间的变化非常小。针叶树提供了最显著的例外，在最近石炭纪出现了相对较小的差异，然后随着连续的、紧密聚集的组成亚支的辐射而逐渐扩大。结论许多分支数据集可以被重新用于研究植物分支随时间的形态差异，并为更有针对性的形态计量学研究提供补充。植物独特的结构和生态特征使它们非常适合于研究差异的内在和外在制约因素。
BackgroundDisparity refers to the morphological variation in a sample of taxa, and is distinct from diversity or taxonomic richness. Diversity and disparity are fundamentally decoupled; many groups attain high levels of disparity early in their evolution, while diversity is still comparatively low. Diversity may subsequently increase even in the face of static or declining disparity by increasingly fine sub-division of morphological ‘design’ space (morphospace). Many animal clades reached high levels of disparity early in their evolution, but there have been few comparable studies of plant clades, despite their profound ecological and evolutionary importance. This study offers a prospective and some preliminary macroevolutionary analyses.MethodsClassical morphometric methods are most suitable when there is reasonable conservation of form, but lose traction where morphological differences become greater (e.g. in comparisons across higher taxa). Discrete character matrices offer one means to compare a greater diversity of forms. This study explores morphospaces derived from eight discrete data sets for major plant clades, and discusses their macroevolutionary implications.Key ResultsMost of the plant clades in this study show initial, high levels of disparity that approach or attain the maximum levels reached subsequently. These plant clades are characterized by an initial phase of evolution during which most regions of their empirical morphospaces are colonized. Angiosperms, palms, pines and ferns show remarkably little variation in disparity through time. Conifers furnish the most marked exception, appearing at relatively low disparity in the latest Carboniferous, before expanding incrementally with the radiation of successive, tightly clustered constituent sub-clades.ConclusionsMany cladistic data sets can be repurposed for investigating the morphological disparity of plant clades through time, and offer insights that are complementary to more focused morphometric studies. The unique structural and ecological features of plants make them ideally suited to investigating intrinsic and extrinsic constraints on disparity.