Sefc Kristina M, Baric Sanja, Salzburger Walter, Sturmbauer Christian
Department of Zoology, Karl Franzens University of Graz, Universitätsplatz 2, A-8010 Graz, Austria.
J Mol Evol. 2007 Jan;64(1):33-49. doi: 10.1007/s00239-006-0011-4. Epub 2006 Dec 9.
Species richness and geographical phenotypic variation in East African lacustrine cichlids are often correlated with ecological specializations and limited dispersal. This study compares mitochondrial and microsatellite genetic diversity and structure among three sympatric rock-dwelling cichlids of Lake Tanganyika, Eretmodus cyanostictus, Tropheus moorii, and Ophthalmotilapia ventralis. The species represent three endemic, phylogenetically distinct tribes (Eretmodini, Tropheini, and Ectodini), and display divergent ecomorphological and behavioral specialization. Sample locations span both continuous, rocky shoreline and a potential dispersal barrier in the form of a muddy bay. High genetic diversity and population differentiation were detected in T. moorii and E. cyanostictus, whereas much lower variation and structure were found in O. ventralis. In particular, while a 7-km-wide muddy bay curtails dispersal in all three species to a similar extent, gene flow along mostly continuous habitat appeared to be controlled by distance in E. cyanostictus, further restricted by site philopatry and/or minor habitat discontinuities in T. moorii, and unrestrained in O. ventralis. In contrast to the general pattern of high gene flow along continuous shorelines in rock-dwelling cichlids of Lake Malawi, our study identifies differences in population structure among stenotopic Lake Tanganyika species. The amount of genetic differentiation among populations was not related to the degree of geographical variation of body color, especially since more phenotypic variation is observed in O. ventralis than in the genetically highly structured E. cyanostictus.
东非湖栖丽鱼科鱼类的物种丰富度和地理表型变异通常与生态特化和有限扩散相关。本研究比较了坦噶尼喀湖三种同域分布的岩栖丽鱼科鱼类——蓝点埃氏丽鱼（Eretmodus cyanostictus）、茉莉凤凰（Tropheus moorii）和腹眼丽鱼（Ophthalmotilapia ventralis）的线粒体和微卫星遗传多样性及结构。这些物种代表了三个地方性、系统发育上不同的族（埃氏丽鱼族、凤凰族和外齿丽鱼族），并表现出不同的生态形态和行为特化。采样地点涵盖了连续的岩石海岸线以及一个呈泥湾形式的潜在扩散障碍。在茉莉凤凰和蓝点埃氏丽鱼中检测到高遗传多样性和种群分化，而腹眼丽鱼的变异和结构则低得多。特别是，虽然一个7公里宽的泥湾在相似程度上限制了所有三个物种的扩散，但在蓝点埃氏丽鱼中，沿着大多连续栖息地的基因流似乎受距离控制，在茉莉凤凰中进一步受到位点归巢和/或微小栖息地不连续性的限制，而在腹眼丽鱼中不受限制。与马拉维湖岩栖丽鱼科鱼类沿着连续海岸线基因流高的一般模式相反，我们的研究确定了狭适性坦噶尼喀湖物种之间种群结构的差异。种群间的遗传分化程度与体色的地理变异程度无关，特别是因为在腹眼丽鱼中观察到的表型变异比在遗传结构高度复杂的蓝点埃氏丽鱼中更多。
