THE FREQUENCY OF SHIFTS BETWEEN ALTERNATIVE EQUILIBRIA
THE FREQUENCY OF SHIFTS BETWEEN ALTERNATIVE EQUILIBRIA
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DOI：
10.1016/s0022-5193(87)80210-2
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发表时间：
1987-04-21
影响因子：
2
通讯作者：
ROUHANI, S
中科院分区：
文献类型：
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作者：
BARTON, NH;ROUHANI, S
我们推导了一个公式，给出了随机漂移使种群在可选均衡之间移动的频率。此公式在此类移位很少见时有效(NS.mchgt.1)，并适用于各种突变率。当进入种群的突变数量较低时(4N.m..mchlt.1)，随机移位率减小为突变率与单个突变的固定概率的乘积。然而，当在每一代中有许多突变进入种群时(4N.m..mchgt.1)，如果突变是独立建立的，那么这一比率将高于预期，并收敛于高斯近似所给出的结果。我们应用关于双稳系统的最新结果，将该公式推广到一般的多维情形。这给出了随机移位频率的显式表达式，它仅取决于分隔交替稳定态的鞍点附近的平衡概率分布。根据这些结果，讨论了随机漂移物种形成理论的合理性。
We derive a formula giving the frequency with which random drift shifts a population between alternative equilibria. This formula is valid when such shifts are rare (Ns .mchgt. 1), and applies over a wide range of mutation rates. When the number of mutations entering the population is low (4N.mu. .mchlt. 1), the rate of stochastic shifts reduces to the product of the mutation rate and the probability of fixation of a single mutation. However, when many mutations enter the population in each generation (4N.mu. .mchgt. 1), the rate is higher than would be expected if mutations were established independently, and converges to that given by a gaussian approximation. We apply recent results on bistable systems to extend this formula to the general multidimensional case. This gives an explicit expression for the frequency of stochastic shifts, which depends only on the equilibrium probability distribution near the saddle point separating the alternative stable states. The plausibility of theories of speciation through random drift are discussed in the light of these results.