Dipartimento di Fisica e Astronomia G. Galilei, Università di Padova, Via Marzolo 8, Padova, 35131, Italy.
Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via Fratelli Cervi 93, Segrat, MI I-20090, Italy.
J Theor Biol. 2019 Dec 21;483:109969. doi: 10.1016/j.jtbi.2019.07.021. Epub 2019 Aug 1.
The evolutionary and ecological processes behind the origin of species are among the most fundamental problems in biology. In fact, many theoretical hypothesis on different type of speciation have been proposed. In particular, models of sympatric speciation leading to the formation of new species without geographical isolation, are based on the niche hypothesis: the diversification of the population is induced by the competition for a limited set of available resources. Interestingly, neutral models of evolution have shown that stochastic forces are sufficient to generate coexistence of different species. In this work, we put forward this dichotomy within the context of species formation, studying how neutral and niche forces contribute to sympatric speciation in a model ecosystem. In particular, we study the evolution of a population of individuals with asexual reproduction whose inherited characters or phenotypes are specified by both niche-based and neutral traits. We analyze the stationary state of the dynamics, and study the distribution of individuals in the whole phenotypic space. We show, both numerically and analytically, that there is a non-trivial coupling between neutral and niche forces induced by stochastic effects in the evolution of the population allowing the formation of clusters, that is, species in the phenotypic space. Remarkably, our framework can be generalized also to sexual reproduction or other type of population dynamics.
物种起源背后的进化和生态过程是生物学中最基本的问题之一。事实上，已经提出了许多关于不同类型物种形成的理论假设。特别是，没有地理隔离的同域物种形成模型基于生态位假说：由于对有限可用资源的竞争，种群的多样化被诱导。有趣的是，进化的中性模型表明，随机力足以产生不同物种的共存。在这项工作中，我们在物种形成的背景下提出了这种二分法，研究中性和生态位力量如何在一个模型生态系统中促进同域物种形成。特别是，我们研究了具有无性繁殖的个体群体的进化，其遗传特征或表型由基于生态位和中性特征共同指定。我们分析了动力学的稳定状态，并研究了整个表型空间中个体的分布。我们通过数值和分析表明，在种群进化过程中，随机效应引起的中性和生态位力量之间存在非平凡的耦合，从而允许在表型空间中形成聚类，即物种。值得注意的是，我们的框架也可以推广到有性繁殖或其他类型的种群动态。
