Some aspects of the genus concept
Some aspects of the genus concept
复制标题
属概念的某些方面
DOI：
10.2307/4109454
复制
发表时间：
1972
期刊：
影响因子：
--
通讯作者：
W. D. Clayton
中科院分区：
文献类型：
--
作者：
W. D. Clayton
概括。属概念代表了对自然现象的主观方法。很难解开自然因素，它本身就非常复杂，而且这个主题充满了猜测，但以下尝试性命题至少有一些合理性。我。准对数分布非常恒定，表明进化过程以相当一致的方式运行，在每个科中产生相似的物种组模式，并且这些组可以被识别为属。 2. 多样性指数差异很大，可能反映了对大属的主观厌恶。 3. 至少在禾本科中，新属的描述速度比发现新种的速度相对要快，属的识别水平也已接近于物种的识别水平。植物分类通常被可视化为树状图，其中分类等级由任意级别的连续横截面表示。就物种而言，人们逐渐发现这一水平与一种生物现象（封闭繁殖系统）相一致。实践中常常发现，封闭育种系统难以定义，与形态实体的吻合不精确，单一的称谓是一种笨拙的过度简化。事实上，分类学家的艺术就是尝试协调物种概念的这三个方面。然而，这种方法足以很好地解释为什么物种被普遍认为是基本单位，并让我们放心，一般来说，整个被子植物都一致使用该等级。第二个主要等级是属。它可能确实存在某种形式，因为它的起源在于林奈之前的民间概念（Bartlett，1940）；但似乎不可能确定它在多大程度上反映了自然界中发现的分组，以及在多大程度上它是人类头脑中的一种分类手段（Walters，i961）。当然，还没有人发现与物种相似的生物现象之间的关系，因此我们没有标准来判断等级是否被一致使用。然而，类属概念有一个属性可以作为比较的基础，那就是科内不同大小属的频率分布。
Summary. The genus concept represents a subjective approach to a natural phenomenon. It is difficult to disentangle the natural element, which is itself very complex, and the subject is fraught with speculation, but there is at least some justification for the following tentative propositions. i. The quasi-logarithmic distribution is remarkably constant, suggesting that evolutionary processes have operated in a reasonably uniform manner to produce a similar pattern of species groups in each family, and that these groups are recognizable as genera. 2. The Index of Diversity varies considerably, and may reflect a subjective dislike of large genera. 3. At least in the Gramineae new genera have been described at a relatively faster rate than new species have been discovered, and the level at which the genus is recognized has risen closer to that of the species. Botanical classification is commonly visualized as a dendrogram, in which the taxonomic ranks are represented by successive cross-sections at arbitrary levels. In the case of species it has gradually become apparent that this level coincides with a biological phenomenon, the closed breeding system. In practice it is often found that the closed breeding system is hard to define, that its coincidence with the morphological entities is inexact, and that the single epithet is a clumsy over-simplification. Indeed the art of the taxonomist is to attempt a reconciliation of these three aspects of the species concept. Nevertheless this approach works sufficiently well to explain why the species is universally recognized as the basic unit, and to reassure us that, in general, the rank is consistently used throughout the Angiosperms. The second main rank is the genus. It presumably has a real existence of some sort, for its origin lies in pre-Linnaean folk concepts (Bartlett, 1940); but it seems impossible to establish to what extent it is a reflection of the groupings found in nature, and to what extent it is a classificatory device in the mind of man (Walters, i961). Certainly no one has yet found any relationship with biological phenomena akin to that of the species, and we have therefore no standard by which to judge whether the rank is employed consistently. There is however one property of the generic concept upon which comparisons may be based, and that is the frequency distribution of genera of different sizes within a family.