NATURAL-SELECTION AND RANDOM GENETIC DRIFT IN PHENOTYPIC EVOLUTION
NATURAL-SELECTION AND RANDOM GENETIC DRIFT IN PHENOTYPIC EVOLUTION
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DOI：
10.2307/2407703
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发表时间：
1976-01-01
期刊：
影响因子：
3.3
通讯作者：
LANDE, R
中科院分区：
文献类型：
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作者：
LANDE, R
本文试图提供一套比种群遗传学的经典模型在宏观进化事件分析中更有用的模型。这是通过更加强调表型参数来实现的。虽然不可能完全成功地用纯粹的表型术语来描述进化，但在许多适合自然种群的情况下，这是可以做到的。Simpson的适应带概念是通过构建表型适应地形来阐明的，类似于Wright的基因频率适应地形。对于大多数表型性状，在自然选择下，群体的平均表型总是向表型空间中平均适应度高的适应区（.hivin. w）进化。频率依赖性选择可能导致平均表型远离其适应区，降低群体中个体的平均适合度；不同类型的频率相关选择被分类为是否会导致这种不适应进化。我们推导出了一个简单的公式，用于估计解释表型进化所必需的每代最小选择性死亡率（假设不涉及遗传漂变）。解释观察到的第三纪哺乳动物牙齿特征的进化速度所需的最低死亡率非常小，通常是每一代百万分之一的选择性死亡。考虑了这些变化是由随机遗传漂变引起的假设。统计测试表明，观察到的这些哺乳动物牙齿特征的进化可能是在大种群中随机遗传漂变发生的，有效大小在数万或数十万。在进化事件的适应性意义不确定的情况下，这种统计测试将是最有趣的。其他假设也被检验，包括在两个可能被随机遗传漂变跨越的适应区之间存在一个选择性阈值。如果稳定选择很弱，并且适应阈值不远，那么适应区之间的随机遗传漂变可能是数百或数千个有效规模群体进化的重要机制。随机遗传漂变可能在表型进化中起重要作用。
An attempt is made to provide a set of models more useful in the analysis of macro-evolutionary events than the classical models of population genetics. This is accomplished by placing increased emphasis on phenotypic parameters. While it is not possible to be completely successful in describing evolution in purely phenotypic terms, in many circumstances appropriate for natural populations this can be done. Simpson''s concept of adaptive zones is clarified by the construction of an adaptive topography for phenotypes, similar to Wright''s adaptive topography for gene frequencies. For most phenotypic characters under natural selection, the evolution of the average phenotype in a population is always toward an adaptive zone of high mean fitness (.hivin.W) in the phenotype space. Frequency-dependent selection may cause the average phenotype to evolve away from its adaptive zone, decreasing the mean fitness of indivduals in the population; different types of frequency-dependent selection are classified as to whether or not they lead to such maladaptive evolution. A simple formula for estimating the minimum selective mortality per generation necessary to explain observed rates of phenotypic evolution is derived (assuming that genetic drift was not involved). The minimum mortality rates needed to explain observed rates of evolution in tooth characters of Tertiary mammals are very small, typically about 1 selective death per million individuals per generation. The hypothesis that these changes were caused by random genetic drift is considered. Statistical tests show that the observed evolution of these mammalian tooth characters could have occurred by random genetic drift in large populations, with effective sizes in the tens or hundreds of thousands. Such statistical tests would be most interesting in cases where the adaptive significance of evolutionary event is uncertain. Other hypotheses are examined, including the existence of a selective threshold between 2 adaptive zones possibly crossed by random genetic drift. If stabilizing selection is weak and an adaptive threshold is not far away, random genetic drift between adaptive zones may be an important mechanism of evolution in populations of effective size in the hundreds or thousands. Random genetic drift may play a significant role in phenotypic evolution.