THE POPULATION-GENETICS OF HAPLO-DIPLOIDS AND X-LINKED GENES
THE POPULATION-GENETICS OF HAPLO-DIPLOIDS AND X-LINKED GENES
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DOI：
10.1017/s0016672300026550
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发表时间：
1984-01-01
影响因子：
1.5
通讯作者：
AVERY, PJ
中科院分区：
文献类型：
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作者：
AVERY, PJ
从现有的电泳数据来看，单倍体昆虫的遗传变异水平比二倍体昆虫低得多，这种差异只能部分地用某些单倍体物种的社会结构来解释。在同一物种中比较x连锁基因和常染色体基因的数据要少得多，而且很少能从中推断出来。这些数据与x连锁基因和单倍体基因的理论分析进行了比较。（x连锁基因和单倍体基因的理论种群遗传学是相同的。）定向选择下的x连锁基因比胞体基因丢失或固定得更快，因为选择更直接地作用于x连锁基因，有效群体规模较小。通过突变压力维持的有害疾病基因在x连锁位点上会有较高的发病率，因此在x连锁位点上更容易检测到罕见突变。考虑到维持平衡多态性的力量，如果要维持遗传变异，x连锁位点的适应度参数比常染色体位点的适应度参数有更强的限制，因此x染色体和单倍体中的多态性位点较少。突变-随机漂移假说还导致由于有效种群大小的减小而导致杂合度降低的预期。理论结果与数据相符，但在x连锁基因和单倍体基因中，是选择还是突变随机漂变维持了大部分的遗传变异，这仍有待争论。
From the available electrophoretic data, haplodiploid insects have a much lower level of genetic variability than diploid insects, a difference that is only partially explained by the social structure of some haplodiploid species. The data comparing X-linked genes and autosomal genes in the same species is much more sparse and little can be inferred from it. This data is compared with theoretical analyses of X-linked genes and genes in haplodiploids. (The theoretical population genetics of X-linked genes and genes in haplodiploids are identical.) X-linked genes under directional selection will be lost or fixed more quickly than atuosomal genes as selection acts more directly on X-linked genes and the effective population size is smaller. Deleterious disease genes, maintained by mutation pressure, will give higher disease incidences at X-linked loci and hence rare mutants are easier to detect at X-linked loci. Considering the forces which can maintain balanced polymorphisms, there are much stronger restrictions on the fitness parameters at X-linked loci than at autosomal loci if genetic variability is to be maintained, and thus fewer polymorphic loci are to be expected on the X-chromosome and in haplodiploids. The mutation-random drift hypothesis also leads to the expectation of lower heterozygosity due to the decrease in effective population size. The theoretical results fit in with the data but it is still subject to argument whether selection or mutation-random drift are maintaining most of the genetic variability at X-linked genes and genes in haplodiploids.