Data from: Refining the conditions for sympatric ecological speciation

Can speciation occur in a single population when different types of resources are available, in the absence of any geographical isolation, or any spatial or temporal variation in selection? The controversial topics of sympatric speciation and ecological speciation have already stimulated many theoretical studies, most of them agreeing on the fact that mechanisms generating disruptive selection, some level of assortment, and enough heterogeneity in the available resources, are critical for sympatric speciation to occur. Few studies, however, have combined the three factors and investigated their interactions. In this article, I analytically derive conditions for sympatric speciation in a general model where the distribution of resources can be uni- or bimodal, and where a parameter controls the range of resources that an individual can exploit. This approach bridges the gap between models of a unimodal continuum of resources and Levene-type models with discrete resources. I then test these conditions against simulation results from a recently published article (Thibert-Plante and Hendry 2011) and confirm that sympatric ecological speciation is favoured when (i) selection is disruptive (ie, individuals with an intermediate trait are at a local fitness minimum), (ii) resources are differentiated enough, and (iii) mating is assortative. I also discuss the role of mating preference functions, and the need (or lack thereof) for bimodality in resource distributions for diversification.

当存在不同类型的可利用资源，且无任何地理隔离、选择的空间或时间变异时，单一种群能否发生物种形成？同域物种形成（sympatric speciation）与生态物种形成（ecological speciation）这两项颇具争议的研究议题，已吸引诸多理论研究。其中多数研究达成共识：能够产生分裂选择（disruptive selection）的机制、一定程度的选型交配（assortative mating），以及可用资源的充分异质性，是同域物种形成发生的关键条件。然而，鲜有研究同时整合这三类因素并探究其交互作用。
本文基于一个通用模型解析推导了同域物种形成的条件：该模型中资源分布可为单峰或双峰，且通过一个参数调控个体可利用的资源范围。该研究框架填补了单峰连续资源模型与离散资源莱文型（Levene-type）模型之间的研究空白。
随后，本文将上述推导条件与近期发表的一项研究（Thibert-Plante与Hendry 2011）中的模拟结果进行对比验证，证实当满足以下三项条件时，同域生态物种形成更易发生：（i）选择为分裂选择（即携带中间表型的个体处于局部适合度最小值）；（ii）资源分化程度足够高；（iii）交配为选型交配。此外，本文还探讨了交配偏好函数的作用，以及物种分化是否需要资源分布呈现双峰性。