The Unit of Selection in DROSOPHILA MERCATORUM. II. Genetic Revolution and the Origin of Coadapted Genomes in Parthenogenetic Strains.
The Unit of Selection in DROSOPHILA MERCATORUM. II. Genetic Revolution and the Origin of Coadapted Genomes in Parthenogenetic Strains.
复制标题
果蝇 MERCATORUM 中的选择单位。
DOI：
10.1093/genetics/92.4.1265
复制
发表时间：
1979
期刊：
影响因子：
3.3
通讯作者：
A. Templeton
中科院分区：
文献类型：
--
作者：
A. Templeton
果蝇是一种有性生殖的物种，可以单性生殖。先前的研究表明，孤雌生殖菌株具有“共适应基因组”，在孤雌生殖和全纯合性下具有高适应性，这是由于分散在整个基因组中的染色体片段之间的非加性和非乘性适应性相互作用。为了研究这种共适应基因组的进化起源，自然界中有性交配的雌性被隔离为处女，并进行单性生殖。对来自这些有性生殖雌性的基因组及其成功的孤雌生殖后代进行了适合度研究。通过跨越从有性生殖到孤雌生殖的生殖过渡，这些适合度研究表明，共适应基因组立即出现，显然是由于伴随生殖过渡的强烈选择性瓶颈，而不是由于孤雌生殖已经建立后通过突变的上位复合物的缓慢积累。生殖过渡也可以作为物种形成的“遗传革命”理论的实验模型，因为过渡涉及（1）最终的创始人效应（一个基因组），（2）最大的遗传漂变和固定，（3）以完全纯合为特征的遗传环境的急剧变化，和（4）与遗传环境的变化以及适应实验室环境和新的繁殖系统的需要相互作用的强烈选择瓶颈。因此，所有理论上支持基因革命的因素都存在，尽管是以极端的形式存在。这项研究表明，遗传革命是真实的现象，可以迅速改变形态，发展，生活史参数和行为。事实上，这些变化可能是如此剧烈，以至于一个新的“物种”进化出来，并具有交配前和交配后的隔离机制。然而，同工酶位点似乎不是这场遗传革命的目标，而是调节基本发育过程的位点。然而，同工酶位点可能是有用的，在预测一个成功的革命的先验机会，因为它们可以表明如何的人口结构的亲本人口影响个人的杂合性水平，在创始人人口的遗传变异的主要来源，必须通过选择瓶颈。
Drosophila mercatorum is a sexual species that can reproduce parthenogenetically. Previous studies revealed that parthenogenetic strains had "coadapted genomes" with high fitness under parthenogenesis and total homozygosity due to nonadditive and nonmultiplicative fitness interactions between chromosomal segments scattered throughout the genome. To study the evolutionary origins of such coadapted genomes, females from sexual matings in nature were isolated as virgins and challenged to reproduce parthenogenetically. Fitness studies were performed on genomes derived from these sexual females and upon their successful parthenogenetic progeny. By straddling the reproductive transition from sex to parthenogenesis, these fitness studies demonstrated that coadapted genomes arise immediately, apparently due to an intense selective bottleneck accompanying the reproductive transition, and are not due to the slow accumulation of epistatic complexes via mutation after parthenogenesis has already been established. The reproductive transition may also serve as an experimental model of the "genetic revolution" theory of speciation because the transition involves (1) the ultimate founder effect (one genome), (2) maximal genetic drift and fixation, (3) a drastic change in genetic environment characterized by total homozygosity, and (4) an intense selective bottleneck that interacts with the change in genetic environment and the need to adapt to a laboratory environment and a novel system of reproduction. Thus, all the elements theorized to underlie genetic revolution are present, albeit in extreme form. This study indicates that genetic revolutions are real phenomena that can quickly alter morphology, development, life history parameters and behavior. Indeed, the alterations can be so drastic that a new "species" evolves, complete with pre- and post-mating isolating mechanisms. However, isozyme loci do not appear to be the target of this genetic revolution, but rather loci regulating fundamental developmental processes. However, isozyme loci may be useful in predicting the a priori chance of a successful revolution since they can indicate how the population structure of the parent population influences levels of individual heterozygosity, the prime source of the genetic variability in the founder population that must pass through the selective bottleneck.