Mestres F, Pegueroles G, Prevosti A, Serra L
Department of Genetics, Faculty of Biology, University of Barcelona, 08071, Barcelona, SPAIN.
Evolution. 1990 Nov;44(7):1823-1836. doi: 10.1111/j.1558-5646.1990.tb05253.x.
In this work, the process of colonization of North and South America by the species Drosophila subobscura has been studied by analyzing the variability of lethal genes. The genetic structures of a Palearctic natural central population (Bordils, Spain) and a colonizer population from America (Gilroy, California) have been compared. The frequencies of lethal chromosomes and their allelism are 29.007% and 0.0069 in the first population and 14.414% and 0.0526 in the American population. A founder effect is detected after the computation of some population parameters (N , h, he and the lethal load). Furthermore, the allelism of lethal chromosomes has revealed a strong association between a lethal gene and the O inversion both in Gilroy and in the population of Puerto Montt (Chile). The interpopulation allelism shows that the O arrangement from the USA and Chile is the same, confirming that the colonizing processes of North and South America are correlated. The O arrangement can also be useful as a genetic marker to trace the origin of the colonization. The frequency of the O arrangement in the original population of the colonization could be used to estimate the number of colonizers. This population is still unknown, but taking the extreme values of the frequency of the O inversion in natural Palearctic populations (1-15%), the number of colonizers could vary between 9 and 149 individuals.
在这项研究中，通过分析致死基因的变异性，对果蝇亚暗果蝇在北美洲和南美洲的定殖过程进行了研究。比较了古北区一个自然中心种群（西班牙博尔迪尔斯）和一个来自美洲的定殖种群（加利福尼亚州吉尔罗伊）的遗传结构。第一个种群中致死染色体的频率及其等位性分别为29.007%和0.0069，而美洲种群中则为14.414%和0.0526。在计算了一些种群参数（N、h、he和致死负荷）后，检测到了奠基者效应。此外，致死染色体的等位性表明，在吉尔罗伊和蒙特港（智利）种群中，一个致死基因与O倒位之间存在强烈关联。种群间的等位性表明，来自美国和智利的O排列是相同的，这证实了北美洲和南美洲的定殖过程是相关的。O排列也可作为一种遗传标记，用于追踪定殖的起源。定殖原始种群中O排列的频率可用于估计定殖者的数量。这个种群仍然未知，但以古北区自然种群中O倒位频率的极值（1-15%）计算，定殖者的数量可能在9至149个个体之间。
