Lessa E P, Cook J A
Laboratorio de Evolución, Facultad de Ciencias, Montevideo, Uruguay.
Mol Phylogenet Evol. 1998 Feb;9(1):88-99. doi: 10.1006/mpev.1997.0445.
Variation in the nucleotide sequence of the entire mitochondrial cytochrome b gene (1140 bp) was examined for 27 individuals representing 13 species of South American rodents of the genera Ctenomys, Octodontomys, Tympanoctomys, and Spalacopus. Representatives of the family Echimyidae, Euryzygomatomys and Mesomys, were used as outgroups to test the monophyly of the Octodontinae and Ctenomyinae. Relationships among species of tuco-tucos (genus Ctenomys) were also examined including representatives of the three described subgenera and the two sperm morphs. Reciprocal monophyly of the Octodontinae and Ctenomyinae is strongly supported. Several basal relationships among species of the genus Ctenomys are poorly resolved, suggesting the possibility of a hard polytomy due to a rapid and potentially simultaneous radiation early in the history of the genus. In other cases, clades within the Ctenomyinae previously identified on the basis of allozymes, chromosomes, parasites, or skull morphology were supported. Calibrations based on the fossil record suggest that the mitochondrial cytochrome b of these caviomorphs has evolved at a rapid rate, comparable to those proposed for Mus-Rattus, and three to four times higher than ungulate rates.
对代表栉鼠属、八齿鼠属、鼓室鼠属和豚鼠属13种南美啮齿动物的27个个体的整个线粒体细胞色素b基因（1140 bp）的核苷酸序列变异进行了检测。刺豚鼠科的代表物种，宽颧鼠属和中鼠属，被用作外类群来检验八齿鼠亚科和栉鼠亚科的单系性。还研究了栉鼠属（tuco-tucos）物种之间的关系，包括三个已描述的亚属和两种精子形态的代表。八齿鼠亚科和栉鼠亚科的相互单系性得到了有力支持。栉鼠属物种之间的几个基部关系尚未得到很好的解决，这表明由于该属历史早期的快速且可能同时发生的辐射，可能存在一个硬多歧分支。在其他情况下，先前基于等位酶、染色体、寄生虫或头骨形态鉴定出的栉鼠亚科内的分支得到了支持。基于化石记录的校准表明，这些豚鼠型动物的线粒体细胞色素b进化速度很快，与小家鼠-大鼠的进化速度相当，比有蹄类动物的进化速度高3至4倍。
