Nestor K E, Anderson J W, Patterson R A
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691, USA.
Poult Sci. 2000 Jul;79(7):937-45. doi: 10.1093/ps/79.7.937.
Bilateral asymmetry was measured at 20 wk of age for shank length, shank width (width laterally at the dew claw), shank depth (width perpendicular to the dew claw), and face length (between auditory canal opening and the posterior junction of the upper and lower mandible) in three randombred control lines and three selected lines of turkeys. The data were based on 50 or 51 individuals per line and sex subgroup from a single hatch. The lines were grown intermingled with the sexes being grown in different houses. The selected lines had been selected for increased egg production (38 generations), increased 16-wk BW (32 generations), or increased shank width (19 generations) and had a higher level of inbreeding (average = 36.9%) than the randombred controls (RBC; average = 11.6%). The bilateral differences (right minus left) were analyzed for the presence of fluctuating asymmetry (FA; zero signed mean with normal variation), directional asymmetry (DA; signed mean not zero with normal variation), and antisymmetry (AS; zero mean with non-normal distribution). In order to adjust for possible scaling effects, relative asymmetry (RA), in which the mean of the absolute differences between sides was divided by the mean of the two sides and the resulting value was multiplied by 100, was used as a measure of bilateral asymmetry. The randombred control and selected lines were contrasted to study the effect of homozygosity on RA. Likewise, the large-bodied lines (F, FL, and RBC3) were contrasted to the small-bodied lines (RBC1, E, and RBC2) to study the effect of BW on RA. Only two types (FA and DA) of asymmetry were observed in the present study. The level of asymmetry for the traits was ranked as follows: face length > shank width = shank depth > shank length. The individual lines differed in RA for shank length and shank width for both sexes and for shank depth and face length in females. In general, the influence of BW, as measured in the contrast of large-bodied and small-bodied lines, on RA was larger than that of homozygosity, as measured by the contrast of the selected and randombred control lines.
在20周龄时，对三个随机交配对照品系和三个选择品系的火鸡测量了小腿长度、小腿宽度（距爪外侧的宽度）、小腿深度（与距爪垂直的宽度）和面部长度（外耳道开口与上下颌后交界处之间的距离）的双侧不对称性。数据基于每个品系和性别亚组来自同一批次孵化的50或51只个体。这些品系混合饲养，雌雄在不同的鸡舍中饲养。选择品系分别经过38代提高产蛋量、32代提高16周龄体重或19代增加小腿宽度的选择，并且其近亲繁殖水平（平均=36.9%）高于随机交配对照品系（RBC；平均=11.6%）。分析双侧差异（右侧减去左侧）以确定是否存在波动不对称（FA；符号均值为零且具有正态变异）、方向不对称（DA；符号均值不为零且具有正态变异）和反对称（AS；均值为零且具有非正态分布）。为了调整可能的尺度效应，使用相对不对称性（RA），即将两侧绝对差异的均值除以两侧均值，再将所得值乘以100，作为双侧不对称性的度量。对比随机交配对照品系和选择品系以研究纯合性对RA的影响。同样，将大体型品系（F、FL和RBC3）与小体型品系（RBC1、E和RBC2）进行对比，以研究体重对RA的影响。在本研究中仅观察到两种类型的不对称性（FA和DA）。性状的不对称水平排序如下：面部长度>小腿宽度=小腿深度>小腿长度。对于小腿长度和小腿宽度，雌雄个体品系之间的RA存在差异，对于雌性的小腿深度和面部长度，品系之间也存在差异。一般来说，通过大体型和小体型品系对比所衡量的体重对RA的影响，大于通过选择品系和随机交配对照品系对比所衡量的纯合性对RA的影响。
