Vagaries in the delimitation of character states in quantitative variation - An experimental study
Vagaries in the delimitation of character states in quantitative variation - An experimental study
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DOI：
10.2307/2413639
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发表时间：
1997-03-01
影响因子：
6.5
通讯作者：
Stevens, PF
中科院分区：
文献类型：
--
作者：
Gift, N;Stevens, PF
对连续变异中特征状态定界的实验研究表明：（1）数据呈现方式影响特征状态的分配;（2）同一数据集中的状态由不同个体以不同方式定界。49个个体被赋予一组图表，表示在属Kalmia（杜鹃花科）和外群的10个字符的变化，所有标识已被删除的图表。变异以三种方式之一表示：线性标尺上的95%置信区间、log（10）标尺上的95%置信区间或线性标尺上显示SD x 2的条形。没有两个人以相同的方式对一组图表进行评分，并且所有人对一种表示中的一个字符进行了相同的评分;当纵坐标从线性变为对数时，该字符的评分完全不同。49个人一起在每个字符中以9到16种不同的方式划分状态。一般来说，由2 × SD条表示的变化引起了最大数量的不同评分，但状态数量相对较少;在这种表示中，图中模式的复杂性是最大的，专家知识在界定这种变异中的状态时似乎具有可疑的价值，并且如果这种特征用于系统发育分析，状态可以由不知道正在评分的研究的细节的人来划分;在任何情况下，在划分状态时，数据的呈现和要遵循的明确协议是必不可少的。在将这种类型的数据转换为性格状态时，心理因素尤其可能发挥作用。我们的实验的其他影响包括thr严重欠确定的一些系统发育假说的观察和形态学数据的异质性。
experimental study on the delimitation of character states in continuous variation indicates that (1) the way data are presented influences the assignment of character states and (2) states in the same data set are delimited in various ways by different individuals. Forty-nine individuals were given a set of graphs denoting variation of 10 characters in the genus Kalmia (Ericaceae) and outgroups, all identification having been removed from the graphs. The variation was represented in one of three ways: as 95% confidence intervals on a linear scale, as 95% confidence intervals on a log(10) scale, or with bars showing SD x 2 on a linear scale. No two individuals scored a set of graphs in the same way, and only one character in one representation was scored identically by all individuals; the scoring ibr this character was completely different when the ordinate was changed from linear to logarithmic. Together; the 49 individuals delimited states within each character between 9 and 16 different ways. In general, variation represented by 2 x SD bars elicited the largest numbers of different scorings, yet with a relatively low number of states; the complexity of the patterns in the graphs in this representation was greatest, Expert knowledge appears to be of dubious value in delimiting states in such variation, and if such characters are to be used in phylogenetic analyses, states could be delimited by people who know nothing of the details of the study being scored; in any case, presentation of data and an explicit protocol to follow when delimiting stales are essential. In converting data of this type into character states, psychological factors are particularly likely to come into play. Other implications of our experiments include thr severe underdetermination of some phylogenetic hypotheses by observation and the heterogeneous nature of morphological data.