1] Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK [2] School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK.
School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK.
Nat Commun. 2014 Feb 28;5:3412. doi: 10.1038/ncomms4412.
Theoretically, competition can initiate divergence in habitat use between individuals of a species, leading to restricted gene flow and eventual speciation. Evidence that sister species differ in habitat use is commonplace and consistent with this mechanism, but empirical experimental support is surprisingly scarce. Here we provide evidence that competition has taken a key role in the evolution of genetically distinct ecomorphs of the Lake Tanganyika cichlid fish Telmatochromis temporalis. Experiments show that differences in substrate use between a large-bodied rock-living ecomorph and a neighbouring small-bodied shell-living ecomorph are mediated by size-dependent competition that drives assortative mate-pair formation. Specifically, adults of the larger ecomorph outcompete adults of the smaller ecomorph on favoured rock substrate, compelling the smaller adults to use shell habitat. These results support a role for competition in maintaining reproductive isolation, and highlight the need to identify ecological processes that impose selection to improve our understanding of speciation and adaptive radiation.
从理论上讲，竞争可以促使一个物种的个体在栖息地利用上产生分歧，从而导致基因流动受限，最终导致物种形成。有证据表明，姐妹物种在栖息地利用上存在差异，这与该机制一致，但令人惊讶的是，经验性的实验支持却很少。在这里，我们提供的证据表明，竞争在坦噶尼喀湖慈鲷鱼 Telmatochromis temporalis 的遗传上不同的生态型的进化中起了关键作用。实验表明，体型较大的岩石生境的生态型和体型较小的壳生境的邻近生态型之间在基质利用上的差异是由大小依赖的竞争所介导的，这种竞争导致了配偶的选择性配对形成。具体来说，较大生态型的成鱼在喜爱的岩石基质上竞争过较小生态型的成鱼，迫使较小的成鱼利用壳生境。这些结果支持了竞争在维持生殖隔离中的作用，并强调需要确定施加选择的生态过程，以提高我们对物种形成和适应性辐射的理解。
