大仓鼠年龄组及性别群体的遗传多样性

本应用随机扩增多态性DNA（RAPD）技术，采用多态位点率、Shannon信息多样性指数和Nei遗传多样性指数作为种群遗传变异的指标，研究了1998和1999年大仓鼠种群性别群体和年龄组群体的遗传多样性。主要的结论是：性别群体间遗传分化较小，年龄组群体间分化较大；年龄组相距越大，遗传分化也就越大；幼年组的遗传多样性高于老龄组的遗传多样性；1999年秋季种群的年龄组遗传分化和差异要比1998年四季种群更为明显。大仓鼠不同年龄组群体间的遗传分化支持遗传结构由于受时空上的选择压力而产生变异和适应性观点。大仓鼠幼体的遗传多样性比成体和老体的较高，这一结果倾向于支持Ford的假说，说明种群繁殖出的幼体遗传多样性高，其中有遗传质量好的，也有遗传质量差的，但在生存过程中，随着选择压力的作用，种群趋于适应，与环境不相适应的类型遭到淘汰，低质的幼体由于自然选择压力的增加而从种群中消失，致使成年和老年群体多态性逐渐降低。

GENETIC DIVERSITY OF SEX AND AGE GROUP OF CRICETULUS TRITON POPULATION

The genetic diversities of sex populations and age group populations of the Rat like hamster ( Cricetulus triton ) populations in 1998 and 1999 were studied by using randomly amplified polymorphic DNA (RAPD) method through the polymerase chain reaction (PCR).The proportion of polymorphic loci, Shannon index and Nei's Index were used to describe the population genetic diversity. It was discovered that the genetic differentiation between male and female group populations was relatively small, while it was greater among four age group populations; the genetic distance increased with increase of age gap; the genetic diversity of juvenile group population was higher than that of older age group populations; the genetic differentiation and difference of autumn population in 1999 were more apparent than that of 4 season populations in 1998.The genetic differentiation among age group populations supported the view that genetic structure experienced change even under the selection in micro time scale. The higher genetic diversity in juvenile age group population supported the Ford hypothesis that the new born animals were genetically diversified, some with better qualities, and some with lower ones. However, under natural selection, the individuals with lower genetic qualities were eliminated. Thus, the juveniles with lower genetic qualities would be disappeared due to the increase in natural selection pressures, while the genetic diversities of adult or old individuals were gradually reduced.