Viñas Jordi, Alvarado Bremer Jaime, Pla Carles
Department of Marine Biology, Texas A&M University at Galveston, 5007 Ave U, Galveston, TX 77551, USA.
Mol Phylogenet Evol. 2004 Oct;33(1):32-42. doi: 10.1016/j.ympev.2004.04.009.
Sequence analysis of the mtDNA control region of four samples (n=195) of Atlantic bonito (Sarda sarda) collected along the northern Mediterranean reveals two clades about 8.1% divergent distributed in an east-west cline that fits an isolation by distance (IBD) model. The vicariant origin of this genetic discontinuity is proposed, supported in addition to the cline, by evidence of distinct historical demographic factors affecting each clade. Variation in Clade I suggests a large stable population, whereas Clade II displays a star-like phylogeny indicative of a population bottleneck followed by sudden expansion. The historical demography and biogeographic scenario is as follows: (1) Allopatric isolation during the Pleistocene give rise to Clade I (Atlantic) and Clade II (Mediterranean); (2) Population collapse followed by sudden expansion gives rise to the characteristic star-like phylogeny of Clade II; (3) Secondary contact as Clade I enters from the Atlantic, and (4) An east-west cline is maintained by IBD.
对沿地中海北部采集的四个大西洋鲣（Sarda sarda）样本（n = 195）的线粒体DNA控制区进行序列分析，发现两个分支，分歧约为8.1%，呈东西渐变群分布，符合距离隔离（IBD）模型。除了渐变群之外，还通过影响每个分支的不同历史人口统计学因素的证据，提出了这种遗传间断的替代起源。分支I中的变异表明有一个大型稳定种群，而分支II呈现出星状系统发育，表明种群瓶颈后突然扩张。历史人口统计学和生物地理情景如下：（1）更新世期间的异域隔离产生了分支I（大西洋）和分支II（地中海）；（2）种群崩溃后突然扩张产生了分支II特有的星状系统发育；（3）随着分支I从大西洋进入，发生二次接触；（4）IBD维持了东西渐变群。
