Department of Ichthyology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA.
BMC Evol Biol. 2010 May 19;10:149. doi: 10.1186/1471-2148-10-149.
It is hypothesized that one of the mechanisms promoting diversification in cichlid fishes in the African Great Lakes has been the well-documented pattern of philopatry along shoreline habitats leading to high levels of genetic isolation among populations. However lake habitats are not the only centers of cichlid biodiversity - certain African rivers also contain large numbers of narrowly endemic species. Patterns of isolation and divergence in these systems have tended to be overlooked and are not well understood.
We examined genetic and morphological divergence among populations of two narrowly endemic cichlid species, Teleogramma depressum and Lamprologus tigripictilis, from a 100 km stretch of the lower Congo River using both nDNA microsatellites and mtDNA markers along with coordinate-based morphological techniques. In L. tigripictilis, the strongest genetic break was concordant with measurable phenotypic divergence but no morphological disjunction was detected for T. depressum despite significant differentiation at mtDNA and nDNA microsatellite markers.
The genetic markers revealed patterns of philopatry and estimates of genetic isolation that are among the highest reported for any African cichlid species over a comparable geographic scale. We hypothesize that the high levels of philopatry observed are generated and maintained by the extreme hydrology of the lower Congo River.
据推测，促进非洲大湖慈鲷鱼类多样化的机制之一是沿海岸线栖息地的强烈亲缘关系模式，导致种群之间存在高度的遗传隔离。然而，湖泊栖息地并不是慈鲷生物多样性的唯一中心 - 某些非洲河流也包含大量的狭窄特有物种。这些系统中的隔离和分化模式往往被忽视，并且了解甚少。
我们使用核 DNA 微卫星和 mtDNA 标记以及基于坐标的形态技术，检查了刚果河下游 100 公里长的一段距离内两种狭窄特有慈鲷物种，Teleogramma depressum 和 Lamprologus tigripictilis 的种群遗传和形态差异。在 L. tigripictilis 中，最强的遗传断裂与可测量的表型差异一致，但在 T. depressum 中没有检测到形态分离，尽管在 mtDNA 和核 DNA 微卫星标记中存在显著分化。
遗传标记揭示了亲代关系和遗传隔离的模式，这是在可比地理范围内报告的任何非洲慈鲷物种中最高的之一。我们假设观察到的高水平亲代关系是由刚果河下游极端的水文学产生和维持的。
