Bowen B W, Nelson W S, Avise J C
Department of Genetics, University of Georgia, Athens 30602.
Proc Natl Acad Sci U S A. 1993 Jun 15;90(12):5574-7. doi: 10.1073/pnas.90.12.5574.
Nucleotide sequences from the cytochrome b gene of mitochondrial DNA were employed to resolve phylogenetic controversies and to assess molecular evolutionary rates in marine turtles (Chelonioidea). Findings of special relevance to conservation biology include discovery of a distant relationship between Natator and other cheloniid species, the paraphyly of Chelonia mydas with respect to Chelonia agassizi, and genetic distinctiveness of Lepidochelys kempi from Lepidochelys olivacea. A longstanding debate in evolutionary ecology was resolved by phylogenetic mapping of dietary habits, which indicates that the spongivore Eretmochelys imbricata evolved from a carnivorous rather than a herbivorous ancestor. Sequence divergences at intergeneric and interfamilial levels, when assessed against fossil-based separation times, support previous suggestions (from microevolutionary comparisons) that mitochondrial DNA in marine turtles evolves much more slowly than under the "conventional" vertebrate clock. This slow pace of nucleotide replacement is consistent with recent hypotheses linking substitution rate to generation length and metabolic pace.
线粒体DNA细胞色素b基因的核苷酸序列被用于解决系统发育争议，并评估海龟（海龟科）的分子进化速率。与保护生物学特别相关的发现包括：发现蠵龟与其他海龟科物种之间的远亲关系、绿蠵龟相对于阿氏蠵龟的并系性，以及丽龟属中大西洋丽龟与太平洋丽龟的遗传独特性。通过对饮食习惯进行系统发育图谱分析，解决了进化生态学中一个长期存在的争论，这表明以海绵为食的玳瑁是从肉食性而非草食性祖先进化而来的。根据基于化石的分离时间评估，属间和科间水平的序列差异支持了之前（来自微观进化比较）的观点，即海龟的线粒体DNA进化速度比“传统”脊椎动物时钟慢得多。这种核苷酸替换的缓慢速度与最近将替换率与世代长度和代谢速度联系起来的假设一致。
