Current procedures for delimiting species   from sequence data aggregate populations lacking discrete differences into a   single species (Cracraft, 1983; Davis and Nixon, 1992; Sites and Marshall,   2003; Wiens and Penkrot, 2002). These “smallest detected sample[s] of   self-perpetuating organisms that have unique sets of characters” (Nelson and Platnick, 1981)   can be recognized based on fixed nucleotide differences unique to such (sets   of) populations (the criterion of “diagnosability”; Cracraft, 1983), implemented in   population aggregation analysis (PAA; Davis and Nixon, 1992). A tree-based variant of this   procedure (cladistic   haplotype analysis; CHA) also considers homoplastic character states   as diagnostic if they are shown to be uniquely derived for a particular group   (Brower, 1999). The Wiens-Penkrot (WP) method (Sites and Marshall, 2003;   Wiens and Penkrot, 2002) is also a tree-based method for delimiting   phylogenetic species but uses the topology (rather than character polarity,   as in CHA) to assess whether or not clades are restricted to a (set of)   populations to the exclusion of clades elsewhere (criterion of   “exclusivity”).

当前从序列数据界定物种的程序将缺乏离散差异的种群聚合为单个物种（Cracraft, 1983; Davis and Nixon, 1992; Sites and Marshall, 2003;   Wiens and Penkrot, 2002）。这些具有独特特征集的自我延续生物体的“最小检测样本”（Nelson and   Platnick, 1981）可根据这些（组）种群特有的固定核苷酸差异（鉴别性标准；Nelson and   Platnick, 1981）加以识别，该标准包含在种群聚集分析中（Paa；Davis和Nixon，1992）。该程序中一个基于树的变异（支序单倍型分析；CHA）也将同形性特征状态视为鉴别特征，如果它们被证明是在特定类群唯一衍生出来的（Brower, 1999）。Wiens-Penkrot   (WP)方法（Sites and Marshall, 2003; Wiens and Penkrot, 2002）也是一种基于树的方法，用于划分系统发生物种，但使用拓扑结构（而不是特征极性，如CHA）来评估支系是否限制在具有排他性的种群水平。