Influence of B locus blood groups on adult mortality and egg production in the White Leghorn chicken.
Influence of B locus blood groups on adult mortality and egg production in the White Leghorn chicken.
复制标题
B 基因座血型对白来航鸡成年死亡率和产蛋量的影响。
作者：
A. Nordskog;W. Rishell;D. M. Briggs
以自交系杂交合成的2个白来客霍恩种群S1和S2为材料，研究了B位点血型对其成虫活力和产蛋量的影响。每系分离出4个B等位基因。在5年的时间里，每系产生了4个纯合子和6个杂合子，在另外3年里，继续对某些血型组合进行测试。共有4371只鸟类参与了这项研究。在S1系中发现了最大的血型差异，B(2)和B（21）等位基因似乎具有有利作用，而B(1)等位基因则具有不利作用。B(1)纯合子的产蛋率最低（53.2%），成虫死亡率最高（40.4%）。在标准偏差单位中，B(1)和B(2)纯合子在成虫死亡率方面的相对差异是产蛋率的三倍以上；B(2)对B(1)不完全显性。在S1系中，杂合子的优势主要是由于B(1)纯合子的适应度较差，这表明在随机交配的群体中，B(1)只能通过突变而不是多态机制来维持。- 8年间，B(1)纯合子成虫存活率每年提高4.4% （P<0.05）。假设这种回归是自然选择的结果，两种假设中的任何一种都可以解释：(1)B基因座是多效性的，自然选择了许多B修饰因子；(2)B基因座是中性的，但与一个主要的适应度基因座有关。
The influence of the B locus blood group on adult viability and egg production was studied in two White Leghorn populations (S1 and S2) synthesized from inbred line crosses. Each line segregated for four B alleles. Four homozygotes and six heterozygotes were produced in each line over a five-year period, and for an additional three years tests on certain blood-group combinations were continued. A total of 4371 birds were included in the study. Greatest differences in blood groups were found in the S1 line, with the B(2) and B(21) alleles seemingly having favorable effects and with B(1) having unfavorable effects. The B(1) homozygote was consistently the lowest in egg production (53.2%) and highest adult mortality (40.4%). The relative spread in standard deviation units between the B(1) and B(2) homozygotes was more than three times greater in adult mortality than in egg production; B(2) was incompletely dominant to B(1). Within the S1 line, the superiority of the heterozygotes was mainly a consequence of the poor fitness of the B(1) homozygote, suggesting that in a random-mated population B(1) would be maintained only by mutation and not by a polymorphic mechanism.-Over the eight years of the experiment, adult viability of the B(1) homozygote improved 4.4% per year (P<0.05). Assuming this regression results from natural selection, either of two hypotheses can account for the results: (1) The B locus is pleiotropic with natural selection for many B modifiers, and (2) the B locus is neutral but linked to a major fitness locus.