Good David A
Museum of Vertebrate Zoology, University of California, Berkeley, CA, 94720.
Evolution. 1989 Jul;43(4):728-744. doi: 10.1111/j.1558-5646.1989.tb05172.x.
The salamander genus Dicamptodon consists of at least four genetically divergent groups of populations with 10-19 fixed allelic differences (out of 31 loci scored) between populations in alternative groups. One of these groups corresponds to D. copei; the other three until now usually have been considered to belong to the single morphologically homogeneous species D. ensatus. Two instances of geographic contact between genetic units occur in the genus, one between D. copei and "D. ensatus" in northern Oregon and the other between two highly divergent types of "D. ensatus" in coastal northern Calfornia. In the former case no hybridization occurs, while in the latter a narrow hybrid zone has been observed. There appears to be selection against hybrids within this hybrid zone, and introgression beyond the zone is apparently nonexistent. The population groups therefore appear to be genetically independent units, and Dicamptodon is best considered to consist of four species: D. copei, D. ensatus, D. tenebrosus, and D. aterrimus.
脊口螈属（Dicamptodon）由至少四个基因上有差异的种群组构成，不同组的种群之间存在10 - 19个固定的等位基因差异（在所检测的31个基因座中）。其中一组对应于科氏脊口螈（D. copei）；另外三组直到现在通常被认为属于形态上单一的物种——太平洋脊口螈（D. ensatus）。该属中基因单位之间存在两个地理接触实例，一个在俄勒冈州北部的科氏脊口螈和“太平洋脊口螈”之间，另一个在加利福尼亚州北部沿海两种高度分化的“太平洋脊口螈”类型之间。在前一种情况下没有杂交现象发生，而在后一种情况下观察到了一个狭窄的杂交带。在这个杂交带内似乎存在对杂交种的选择，并且显然不存在杂交带之外的基因渗入。因此，这些种群组似乎是基因上独立的单位，最好将脊口螈属视为由四个物种组成：科氏脊口螈、太平洋脊口螈、暗黑脊口螈（D. tenebrosus）和深黑脊口螈（D. aterrimus）。
