Bürger Reinhard, Schneider Kristan A
Department of Mathematics, University of Vienna, Nordbergstrasse 15, 1090 Vienna, Austria.
Am Nat. 2006 Feb;167(2):190-205. doi: 10.1086/499375. Epub 2006 Jan 9.
Ecologically driven sympatric speciation has received much attention recently. We investigate a multilocus model of a quantitative trait that is under frequency-dependent selection caused by intraspecific competition and acts as mating character for assortment. We identify the conditions that lead to the establishment of reproductively isolated clusters. This may be interpreted as evolutionary splitting or sympatric speciation. In our model, there are parameters that independently determine the strength of assortment, the costs for being choosy, and the strength of frequency-dependent natural selection. Sufficiently strong frequency dependence leads to disruptive selection on the phenotypes. The population consists of (sexual) haploid individuals. If frequency dependence is strong enough to induce disruptive selection and costs are absent or low, the result of evolution depends in a distinctive nonlinear way on the strength of assortment: under moderately strong assortment, less genetic variation is maintained than under weak or strong assortment, and sometimes there is none at all. Evolutionary splitting occurs only if frequency dependence and assortment are both strong enough and costs are low. Even then, the evolutionary outcome depends on the genetics and the initial conditions. The roles of the number of loci, of linkage, and of asymmetric selection are also explored.
生态驱动的同域物种形成最近受到了广泛关注。我们研究了一个多基因座模型，该模型涉及一个数量性状，该性状受到种内竞争引起的频率依赖选择，并作为分类的交配特征。我们确定了导致生殖隔离簇建立的条件。这可以解释为进化分裂或同域物种形成。在我们的模型中，有一些参数可以独立地决定分类的强度、挑剔的成本以及频率依赖自然选择的强度。足够强的频率依赖性会导致对表型的分裂选择。种群由（有性）单倍体个体组成。如果频率依赖性足够强以诱导分裂选择且成本不存在或较低，进化的结果以一种独特的非线性方式取决于分类的强度：在中等强度的分类下，维持的遗传变异比在弱分类或强分类下更少，有时甚至根本没有。只有当频率依赖性和分类都足够强且成本较低时，才会发生进化分裂。即便如此，进化结果仍取决于遗传学和初始条件。我们还探讨了基因座数量、连锁以及不对称选择的作用。
