Wójcik Anna M, Polly P David, Sikorski Michał D, Wójcik Jan M
Mammal Research Institute, Polish Academy of Sciences, 17-230 Białowieza, Poland.
Evolution. 2006 Sep;60(9):1925-35.
Population density cycles influence phenotypic evolution through both density-dependent selection during periods of high density and through enhanced genetic drift during periods of low density. We investigated the response of different phenotypic traits to the same density cycles in a population of the yellow-necked mouse, Apodemus flavicollis, from Białowieza National Park in Poland. We examined nonmetric skull traits, skull and mandible size, skull and mandible shape, and transferrin allele frequencies. We found that all of the traits changed significantly over the seven-year study period. The greatest changes in nonmetric traits and mandible size occurred during periods of increasing density, and the magnitude of changes in skull and mandible shape was correlated with the magnitude of density changes. Frequencies of transferrin alleles changed the most when population density was in decline. Changes among the five phenotypic traits were generally uncorrelated with one another, except for skull and mandible shape. Nonmetric traits were selectively neutral when assessed with Q(ST)/F(ST) analysis, whereas mandible size, mandible shape, and skull shape showed evidence of fairly strong selection. Selection on skull size was weak or nonexistent. We discuss how different assumptions about the genetic components of variance affect Q(ST) estimates when phenotypic variances are substituted for genetic ones. We also found that change in mandible size, mandible shape, skull size, and skull shape were greater than expected under a neutral model given reasonable assumptions about heritability and effective population size.
种群密度周期通过高密度时期的密度依赖选择以及低密度时期增强的遗传漂变来影响表型进化。我们在来自波兰比亚沃维耶扎国家公园的黄颈姬鼠（Apodemus flavicollis）种群中，研究了不同表型性状对相同密度周期的响应。我们检查了非测量性头骨性状、头骨和下颌骨大小、头骨和下颌骨形状以及转铁蛋白等位基因频率。我们发现，在为期七年的研究期间，所有性状都发生了显著变化。非测量性状和下颌骨大小的最大变化发生在密度增加的时期，头骨和下颌骨形状的变化幅度与密度变化幅度相关。当种群密度下降时，转铁蛋白等位基因频率变化最大。除了头骨和下颌骨形状外，五个表型性状之间的变化通常彼此不相关。用Q(ST)/F(ST)分析评估时，非测量性状是选择性中性的，而下颌骨大小、下颌骨形状和头骨形状显示出相当强烈的选择证据。对头骨大小的选择较弱或不存在。我们讨论了在将表型方差替代遗传方差时，关于方差遗传成分的不同假设如何影响Q(ST)估计。我们还发现，在对遗传力和有效种群大小进行合理假设的中性模型下，下颌骨大小、下颌骨形状、头骨大小和头骨形状的变化大于预期。
