自振荡频率的噪声有利于种群规模的增大

Noise of the Free-Running Frequency Increases the Population of the Species

摘要: 生物的生理和行为活动能在持续黑暗下显示出接近于24小时的自振荡周期。各种物种的自振荡周期不完全一样，大概分布在22小时到28小时之间。另外各物种内的个体之间的自振荡周期也不一样，例如黑人比其他人种的自振荡周期要短，女人的自振荡周期显著比男人短。进一步地，即使同一个个体的自振荡周期受自身因素的影响也不是稳定不变的。Daido为物种之间的差异性提出了一种解释，认为物种之间的自振荡周期的差异性来源于物种之间的竞争，即最接近外界自然周期的物种并不一定会处于最优的状态。本文在Daido的模型基础上，引入了物种自振荡频率的噪声，并发现该噪声有利于种群规模的增加。这种噪声可能来自于个体自振荡周期的不稳定性和同一物种内不同个体之间自振荡周期的差异性。本文的研究有助于理解自然界中为什么会存在这种不稳定性和差异性。

Abstract: Circadian free-running periods exist in the physiological or behavioral activities in living beings even under constant darkness. It was found that the free-running periods are not identical between species, which range from 22 h to 28 h. Furthermore, the free-running periods are not identical between individuals within the same species. For example, it is shorter of American Africans than other races and also shorter of women than man. Interestingly, even for the same living being, the free-running period is not stable which depends on its own factors. Daido raised a model to explain the nonidentity between species, where the nonidentity originates from the competition between species, i.e., the species whose frequency is closest to the environmental frequency is not necessarily in the optimum state. In the present study, based on the Daido's model, the noise in the free-running frequency is introduced and we found that the noise increases the population of the species. This noise potentially originates from the instability of the free-running periods within one individual as well as the nonidentity between individuals within one species. Our finding sheds light on the existence of this instability and nonidentity in nature.