Differences in Evolutionary Pattern and Variability between mtDNA Cytochrome b and Control Region of the Flathead Mullet Mugil cephalus from the Northwest Pacific

西北太平洋烏魚粒線體DNA中細胞色素b及控制區在演化形式及變異性上之差異

Brian Wade Jamandre ； Jean-Dominique Durand ； 沈康寧(Kang-Ning Shen) ； 曾萬年(Wann-Nian Tzeng)

《臺灣水產學會刊》 37卷3期 (2010/09) Pp. 163-172

https://doi.org/10.29822/JFST.201009.0001

摘要

粒線體DNA中的細胞色素b及控制區是研究魚類類緣關係常用的兩種遺傳標誌。然而，我們對於這兩種遺傳標誌的特性及變異性並不清楚。為了了解這兩種遺傳標誌在分子演化形式上的差異，我們定序並比較西北太平洋兩個烏魚演化支序在這兩種基因結構及形式的多樣性。此兩演化支序的核酸組成分別為：細胞色素b（大約1138 bp）的A=24.5%，C=31.4%，T=29.2%，G=15.0%和控制區（大約909-1015 bp）的A=36.4%，C=20.2%，T=30.5%，G=12.9%。此兩演化支序的Tamura-Nei遺傳距離在種內的比較來說相對較高，但依粒線體基因種類而有程度上的不同。遺傳距離分別為細胞色素b的0.0580+0.0070及控制區的0.4850+0.0700。和細胞色素b比較起來，非編碼區的控制區有較高的核酸取代率、不同的最適取代模式及中性測試中顯著的負值。粒線體基因在核酸的取代並無明顯的飽和現象。此結果顯示烏魚粒線體基因體變異的複雜性。因此，對於烏魚遺傳標誌進一步的綜合性分析對於烏魚類緣地理學會有更好的推論。

關鍵字

粒線體DNA ； 控制區 ； 細胞色素b ； 烏魚 ； 演化速率 ； 遺傳奇異度

並列摘要

Mitochondrial DNA control region (mtDNA CR) and cytochrome b (cyt b) are well-known genetic makers for studying phylogeography of fishes. However, characters and variability of these two genetic markers have not been thoroughly understood. To understand how molecular evolution patterns differ between the two genes, we sequenced and compared the structure and patterns of the diversity between cyt b and CR genes of the flathead mullet M. cephalus species complex in the northwest Pacific, which was previously found to have two lineages. Nucleotide base composition of these two lineages were A=24.5%, C=31.4%, T=29.2%, and G=15.0% for cyt b (about 1138 bp), and A=36.4%, C=20.2%, T=30.5%, and G=12.9% for CR (about 909-1015 bp). Tamura-Nei genetic distances between the two lineages were relatively high for the intra-specific comparison but differed only in degree depending on the mtDNA gene. The distances were 0.0580±0.0070 for cyt b and 0.4850±0.0700 for CR. As compared to cyt b, the non-coding CR had higher level of nucleotide substitutions, different best-fit model of the substitutions, and significant negative values of neutrality tests. There was no clear saturation on the nucleotide substitutions from the mtDNA genes. The results indicated the complexity of the mtDNA genome variability in M. cephalus. A further comprehensive analysis of genetic markers is required for better phylogeographic inference of the mullet.

並列關鍵字

mtDNA control region ； Cytochrome b ； Mugil cephalus ； Evolutionary rate ； Genetic divergence