A survey of seed and seedling characters in 1744 Australian dicotyledon species: cross-species trait correlations and correlated trait-shifts within evolutionary lineages
A survey of seed and seedling characters in 1744 Australian dicotyledon species: cross-species trait correlations and correlated trait-shifts within evolutionary lineages
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1744 种澳大利亚双子叶植物种子和幼苗特征的调查：跨物种性状相关性和进化谱系内的相关性状转变
DOI：
10.1111/j.1095-8312.2000.tb01222.x
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发表时间：
2000
影响因子：
1.9
通讯作者：
M. Westoby
中科院分区：
文献类型：
--
作者：
I. Wright;H. Clifford;R. Kidson;M. Reed;B. Rice;M. Westoby
摘要幼苗性状已被描述在1744种澳大利亚植物中。六个性状被编码为二元选择：（1）显子叶与隐子叶;（2）第一片叶鳞片状与叶状;（3）第一片叶单个与成对;（4）子叶有毛与无毛;（5）下胚轴有毛与无毛;（6）胚成熟时绿色与非绿色。根据种子尺寸的测量值计算种子体积。在分析数据时使用了三种方法：（1）描述二元性状状态的分类学分布;（2）在物种水平上量化二元性状关联的强度（«跨物种»相关性和回归）;（3）将数据排列在系统发育树上，以便通过«系统发育回归»分析性状对中相关的进化变化。所有这些特征似乎都具有进化可塑性。例如，虽然隐子叶是少数情况（占物种的22%），但它存在于许多不同的分类群（124属、40科、24目）中，具有高水平的多态性（属、科和目分别为16%、25%和42%）。同样，第一叶型，下胚轴质地，子叶质地和胚颜色的不太常见的属性状态发生在物种从权利横跨双子叶植物的发育，因为独立的进化分歧，在这些字符。这些模式表明，关于哪些条件是原始的，哪些条件是先进的争论不会有任何普遍的答案，只有系统发育树中特定分支步骤的答案。在几乎所有的情况下，相关发散分析表明，跨物种分析相同的模式。种子体积与隐子叶、鳞片状第一叶、绿色胚之间的相关性最强。此外，隐子叶和鳞片状的第一叶，子叶和下胚轴类型，强烈相关的分歧和跨种分析。对结果的解释主要是关于种子大小，我们认为这是一个物种幼苗建立策略的关键特征。在我们的研究物种中发现了所有可能的二元幼苗性状的成对组合。总之，这里提出的各种证据表明，这些特征或多或少是相互独立的，并且没有提供基于这些属性的功能组的证据。因此，现有的几种幼苗类型学应被视为方便的分类，而不是反映基本类型。
Abstract Seedling traits have been described across 1744 species of Australian plants. Six traits were coded as binary alternatives: (1) phanerocotyly vs cryptocotyly; (2) first leaf scale-like vs leaf-like; (3) first leaf single vs paired; (4) cotyledons hairy vs. glabrous; (5) hypocotyl hairy vs glabrous, and (6) embryo green vs non-green at maturity. Seed volume was calculated from measurements of seed dimensions. Three approaches were used in analysing the data: (1) the taxonomic distribution of binary character states was described; (2) the strength of bivariate character associations was quantified at species level («cross-species» correlations and regressions); (3) the data were arrayed on a phylogenetic tree in order to analyse by «phylogenetic regression» for correlated evolutionary shifts in trait pairs. All the traits appeared evolutionarily malleable. For example, while cryptocotyly was the minority condition (22% of species), it occurred in many different taxa (124 genera, 40 families, 24 orders) with high levels of polymorphy (16%, 25% and 42% for genera, families and orders). Similarly, the less common attribute states for first leaf type, hypocotyl texture, cotyledon texture and embryo colour occurred in species from right across the dicotyledon phylogeny, as did independent evolutionary divergences in each of these characters. These patterns indicate that debate over which conditions are primitive and which are advanced will not have any general answer, only an answer for a specific branch-step in the phylogenetic tree. In nearly all cases, correlated-divergence analyses showed the same patterns as cross-species analyses. The strongest associations were between seed volume and cryptocotyly, seed volume and scale-like first leaf, and seed volume and presence of green embryo. In addition, cryptocotyly and scale-like first leaf, and cotyledon and hypocotyl type, were strongly associated in both correlated-divergence and cross-species analyses. Interpretation of results was mostly presented with respect to seed size, a trait which we consider to be pivotal in a species» seedling establishment strategy. All possible pairwise combinations of binary seedling traits were found in our study species. Taken together, the various lines of evidence presented here suggest that the traits have assorted more or less independently of each other and provide no evidence of functional groups based on these attributes. Thus, the several existing seedling typologies should be regarded as classifications of convenience rather than as reflecting fundamental types.