Bryant Edwin H, Meffert Lisa M
Department of Biology, University of Houston, Houston, TX, 77004.
Evolution. 1990 May;44(3):660-668. doi: 10.1111/j.1558-5646.1990.tb05946.x.
Multivariate phenotypic differentiation in eight morphometric traits was examined in bottleneck lines of the housefly initiated with one, four, or 16 pairs of flies from a natural outbred population. Differentiation was assessed using a Mahalanobis' distance metric in units of additive genetic variance and covariance estimated from the ancestral population (i.e., generalized genetic distance). This distance metric was partitioned into contributions of size and shape to total distance. Bottleneck lines of all sizes diverged significantly from the ancestral line, but the direction of these shifts differed among the lines of different initial founding size. Those populations founded with single pairs diverged from the ancestral line mostly in shape; the 16-pair lines differentiated almost entirely in size, and the four-pair lines were intermediate in the relative contribution of shape to differentiation from the control. Bottlenecks serve to alter the genetic relationships among traits within the derived populations and in doing so could promote speciation by permitting differentiation of the populations along evolutionary trajectories less accessible to the base population.
在由来自自然远交群体的一对、四对或十六对家蝇起始建立的瓶颈系中，对八个形态测量性状的多变量表型分化进行了研究。使用马氏距离度量来评估分化，该距离度量以从祖先群体估计的加性遗传方差和协方差为单位（即广义遗传距离）。这个距离度量被划分为大小和形状对总距离的贡献。所有大小的瓶颈系都与祖先系有显著差异，但这些变化的方向在不同初始奠基大小的系中有所不同。那些由单对起始建立的群体与祖先系的差异主要在形状上；十六对起始建立的系几乎完全在大小上发生分化，而四对起始建立的系在形状相对于与对照分化的贡献方面处于中间状态。瓶颈效应有助于改变衍生群体内性状之间的遗传关系，并且这样做可以通过允许群体沿着基础群体较难进入的进化轨迹进行分化来促进物种形成。
