在过去的几年里,在小空间尺度上对进化分歧的兴趣增加了,对基于生态的分歧自然选择引起的物种形成的研究也增加了。基因流和局部适应之间的进化相互作用可以导致低分散的局部适应专家。当这种情况发生时,基因流和局部适应之间的进化相互作用最终可能导致物种形成。saxatilis乳杆菌系统由两种生态型组成,它们沿着加利西亚的波浪暴露的岩石海岸显示出微生境相关的种内二态现象。尽管是一个众所周知的系统,生态型形成的动态尚不清楚,不能仅从经验证据进行研究。在这项研究中,基于个人的模拟被用来纳入相关的生态,空间,和遗传信息,检查不同的进化场景,这些场景可能会进化出非随机的交配偏好,最终可能会促进物种形成。作为主要结果,我们观察到选择的中间值的演变,这与加利西亚海岸的萨克斯氏乳杆菌的经验数据的估计相符,并且与以前的理论结果一致。此外,使用交配相关性作为分类交配的代理,导致虚假地推断中间栖息地比其他栖息地更大的生殖隔离,这在直接考虑模拟中的选择值时不会发生。我们还证实了一个众所周知的事实,即物种形成的发生受选择强度的影响。一起来看,这意味着,同样根据其他萨克斯氏杆菌系统,物种形成并不是当地不同选择和交配偏好的直接结果,但是在几个因素之间进行微调,包括岸上的生态条件,选择的力量,配偶选择的严格性,和成本选择。沙克氏乳杆菌系统可能对应于不完全生殖隔离的情况,选择强度中等,栖息地内的局部适应性很强。这些结果支持先前对萨克斯氏乳杆菌模型系统的解释,并表明进一步的实证研究对于测试配偶选择机制是否像其他小牛中所显示的那样具有相似性机制将是有趣的。
In the last years, the interest in evolutionary divergence at small spatial scales has increased and so did the
study of speciation caused by ecologically based divergent natural selection. The evolutionary interplay between gene flow and local adaptation can lead to low-dispersal locally adapted specialists. When this occurs, the evolutionary interplay between gene flow and local adaptation could eventually lead to speciation. The L. saxatilis system consists of two ecotypes displaying a microhabitat-associated intraspecific dimorphism along the wave-exposed rocky shores of Galicia. Despite being a well-known system, the dynamics of the ecotype formation remain unclear and cannot be studied from empirical evidence alone. In this
study, individual-based simulations were used to incorporate relevant ecological, spatial, and genetic information, to check different evolutionary scenarios that could evolve non-random mating preferences and finally may facilitate speciation. As main results, we observed the evolution of intermediate values of choice which matches the estimates from empirical data of L. saxatilis in Galician shores and coincides with previous theoretical outcomes. Also, the use of the mating correlation as a proxy for assortative mating led to spuriously inferring greater reproductive isolation in the middle habitat than in the others, which does not happen when directly considering the choice values from the simulations. We also corroborate the well-known fact that the occurrence of speciation is influenced by the strength of selection. Taken together, this means, also according to other L. saxatilis systems, that speciation is not an immediate consequence of local divergent selection and mating preferences, but a fine tuning among several factors including the ecological conditions in the shore levels, the selection strength, the mate choice stringency, and cost to choosiness. The L. saxatilis system could correspond to a case of incomplete reproductive isolation, where the choice intensity is intermediate and local adaptation within the habitat is strong. These results support previous interpretations of the L. saxatilis model system and indicate that further empirical studies would be interesting to test whether the mate choice mechanism functions as a similarity-like mechanism as has been shown in other littorinids.