Zhdanova Oksana L, Frisman Efim Ya
Insititute for Automation and Control Processes, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041, Russia.
Institute for Complex Analysis of Regional Problem, Far Eastern Branch, Russian Academy of Sciences, Birobidzhan 679016, Russia.
J Theor Biol. 2021 Mar 7;512:110564. doi: 10.1016/j.jtbi.2020.110564. Epub 2021 Jan 5.
Maternal selection and overlapping generations can facilitate the stable coexistence of alleles under temporally fluctuating environment. Using mathematical models, we considered the complex effect of both factors on the maintenance of genetic polymorphism in cyclically changing environments. We concentrated on asymmetric cyclic selection, which allows describing fluctuations of environments by analogy of food resources cycles with rare peaks and prolonged decline of prey abundance. The complex effect of maternal selection and overlapping generations turned out to work as follows: although overlapping generations always tend to dilate the polymorphism region, odd and even external cycles produce different types of polymorphism regions. Maternal selection under external odd cycles extends the coexistence region comparing with classic selection. Even cycles produce a part of parameter region, where the picture changes radically, and classic selection becomes more effective in maintaining polymorphism. Our models have clear biological interpretation, because we tried to model a situation demonstrated by natural populations of arctic foxes. The litter size being a major life history trait is a sex-limited female trait. It is influenced by maternal selection with cyclical fluctuations because of oscillations in food abundance. Arctic fox is a long-lived species having an age structure. The obtained results showed that compared with the simple Mendelian inheritance in the classic model, this trait inheritance allows polymorphism to be maintained in a wider range of the parameter that characterizes the advantage of survival in a small litter. Besides, adding overlapping generations to the model further broadens the parameter space for the protected polymorphism. Thus, this study shows that maternal selection and overlapping generations increases the chances of maintaining polymorphism in populations of arctic foxes.
母体选择和世代重叠能够促进等位基因在时间波动环境下的稳定共存。通过数学模型，我们考虑了这两个因素对周期性变化环境中遗传多态性维持的复杂影响。我们专注于不对称循环选择，它可以通过类比食物资源循环（具有罕见峰值和猎物丰度的长期下降）来描述环境波动。母体选择和世代重叠的复杂影响如下：尽管世代重叠总是倾向于扩大多态性区域，但奇数和偶数外部循环会产生不同类型的多态性区域。与经典选择相比，外部奇数循环下的母体选择扩展了共存区域。偶数循环产生了一部分参数区域，在该区域情况发生了根本性变化，经典选择在维持多态性方面变得更有效。我们的模型具有清晰的生物学解释，因为我们试图模拟北极狐自然种群所展示的一种情况。窝仔数作为一个主要的生活史特征是雌性特有的性状。由于食物丰度的波动，它受到具有周期性波动的母体选择的影响。北极狐是具有年龄结构的长寿物种。所得结果表明，与经典模型中的简单孟德尔遗传相比，这种性状遗传允许多态性在更广泛的参数范围内得以维持，该参数表征了小窝仔数中生存优势。此外，在模型中加入世代重叠进一步拓宽了受保护多态性的参数空间。因此，本研究表明母体选择和世代重叠增加了北极狐种群中维持多态性的机会。
