Abstract

The assumption of low hybrid fitness serves as the cornerstone in the logical justification of the discreteness of species in terms of the biological concept. The majority of natural hybrid zones are narrow and stable in time; thus, this proves, as mathematical models have shown, the existence of selection against hybrids. It is assumed that, since the coadaptive gene complexes of the parent forms are destroyed in hybrids, they must be less viable and/or fertile. However, this statement remains no more than a hypothesis. The low reproductive success of hybrids may have other causes, e.g., they may have difficulties in pair formation because of the rarity and strangeness of their appearance. A computer simulation model has been constructed to verify this assumption. The main purpose of this work is to give answers to the following questions. (1) Is it possible to form a narrow and stable hybrid zone with assortative mating but without lower viability and fertility of the hybrids? Assortative mating in the model is due to sexual imprinting: descendants remember the image of one of their parents and seek an appropriate partner. (2) Is it possible to complete the speciation process under these conditions and what is necessary for this? Here, we interpret speciation as the process of the establishment of sympatry between the initially allopatric forms with the maintenance of their appearance and a low level of hybridization. The model study gave positive answers for both questions. Without biotopic segregation and with assortative mating, the hybrid zone is narrow and stable in time. Hybrids remain unmated more often than parent forms (5–8 and 1–3% respectively), which results in selection pressure in favor of a narrow hybrid zone. In addition to assortative mating, biotopic segregation is necessary to establish sympatry, and hybrids have to be less successful than parent forms in the occupation of an individual territory. In opposite case, when the biotopes of the both parent forms are optimal for hybrids, the contact zone became wider at first and then, after the smoothing of biotopic segregation, they started to slowly shrink to a narrow hybrid zone. As a result, the two forms became indistinguishable by selectively neutral loci (DNA markers analog) over the entire space of the model.

中文翻译：

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杂种区的计算机仿真模型：选择交配对杂种的选择作用

摘要

就生物学概念而言，低杂种适应度的假设是物种离散性的逻辑证明的基石。大多数自然杂交区在时间上都很狭窄和稳定。因此，正如数学模型所示，这证明了针对杂种的选择的存在。据推测，由于亲本形式的亲和性基因复合物在杂种中被破坏，因此它们的生存能力和/或繁殖力必须较低。但是，该陈述仅是一个假设。杂种的低繁殖成功率可能还有其他原因，例如，由于外观的稀有性和陌生性，它们可能很难成对。已经构建了计算机仿真模型以验证该假设。这项工作的主要目的是为以下问题提供答案。（1）是否有可能形成一个狭窄而稳定的杂种区，进行杂种交配，但没有降低杂种的生存力和繁殖力？模型中的各种交配归因于性烙印：后代会记住其父母之一的形象并寻找合适的伴侣。（2）在这些条件下是否有可能完成物种形成过程，这有什么必要？在这里，我们将物种形成解释为在初始异相形式之间保持其外观和低水平杂交的共形建立过程。模型研究对两个问题都给出了肯定的答案。在没有生物隔离和分类交配的情况下，杂交区较窄且时间稳定。杂种比亲本保持不交配的频率更高（分别为5-8％和1-3％），这导致选择压力有利于狭窄的杂交区。除了分类交配之外，生物位隔离对于建立共生体也是必要的，并且在占领单个领土时，杂种必须不如亲本成功。在相反的情况下，当两种亲本形式的生物位都最适合杂种时，接触区首先变宽，然后，在生物位隔离变平滑后，它们开始缓慢收缩到狭窄的杂种区。结果，在模型的整个空间上，这两种形式通过选择性中性位点（DNA标记类似物）变得无法区分。混合型在占领单个领土方面必须不如父母型成功。在相反的情况下，当两种亲本形式的生物位都最适合杂种时，接触区首先变宽，然后，在生物位隔离变平滑后，它们开始缓慢收缩到狭窄的杂种区。结果，在模型的整个空间上，这两种形式通过选择性中性位点（DNA标记类似物）变得无法区分。混合型在占领单个领土方面必须不如父母型成功。在相反的情况下，当两种亲本形式的生物位都最适合杂种时，接触区首先变宽，然后，在生物位隔离变平滑后，它们开始缓慢收缩到狭窄的杂种区。结果，在模型的整个空间上，这两种形式通过选择性中性位点（DNA标记类似物）变得无法区分。