Taylor M I, Rüber L, Verheyen E
Royal Belgian Institute of Natural Sciences, Brussels, Belgium.
Proc Biol Sci. 2001 Apr 22;268(1469):803-8. doi: 10.1098/rspb.2000.1580.
This study investigated fine-scale population substructuring in an apparently monogamous, biparental mouth-brooding cichlid. Microsatellite allele frequencies were determined at four polymorphic loci for nine populations of Eretmodus cyanostictus. We provide empirical support for the hypothesis that a species employing this breeding strategy should exhibit high levels of population substructuring. Stretches of sand represent considerable barriers to dispersal and, in contrast to the rock-dwelling cichlids of Lake Malawi, distance alone, along a continuous rocky shoreline, is sufficient to reduce gene flow significantly There was a significant pattern of isolation by distance both along the whole study area and over the stretch of continuous shoreline, suggesting that this species has poor dispersal capabilities and that juveniles establish territories close to their natal site. Despite limited dispersal, E. cyanostictus populations are not significantly more inbred than a more-widely dispersing rock-dwelling cichlid from Lake Malawi. This finding may cast doubt on the hypothesis that polyandry has evolved as a mechanism for maintaining genetic diversity in Lake Malawi cichlids. High levels of substructuring may not always promote high levels of speciation, and other factors, such as the intensity of sexual selection, may be more important in determining the speciation potential of a lineage.
本研究调查了一种明显实行一夫一妻制、双亲口孵的丽鱼科鱼类的精细种群亚结构。在9个蓝点埃氏丽鱼种群的4个多态位点上测定了微卫星等位基因频率。我们为以下假设提供了实证支持：采用这种繁殖策略的物种应表现出高水平的种群亚结构。沙地对扩散构成了相当大的障碍，与马拉维湖的岩栖丽鱼不同，沿着连续的岩石海岸线，仅距离因素就足以显著减少基因流动。在整个研究区域以及连续海岸线区域，均存在显著的距离隔离模式，这表明该物种的扩散能力较差，且幼鱼会在靠近其出生地的地方建立领地。尽管扩散有限，但蓝点埃氏丽鱼种群的近亲繁殖程度并不比来自马拉维湖的扩散更广的岩栖丽鱼显著更高。这一发现可能会对以下假设产生质疑：一妻多夫制已进化成为维持马拉维湖丽鱼遗传多样性的一种机制。高水平的亚结构并不总是会促进高水平的物种形成，而其他因素，如性选择的强度，在决定一个谱系的物种形成潜力方面可能更为重要。
