Matthews T C, Munstermann L E
Department of Biology, Millikin University, Decatur, Illinois, 62522.
Yale University School of Medicine, Department of Epidemiology & Public Health, 60 College Street, 606 LEPH, New Haven, Connecticut, 06510.
Evolution. 1994 Feb;48(1):146-154. doi: 10.1111/j.1558-5646.1994.tb01301.x.
Chromosome number and morphology in mosquitoes is remarkably uniform: virtually all mosquitoes have a diploid chromosome number of six (2N = 6), and their chromosomes are invariably metacentric or submetacentric. Numerical changes obviously have not been important in mosquito chromosomal evolution, and because of the morphological similarity of their chromosomes, it appears that structural changes have played little or no role in mosquito karyotypic evolution. The goal of the present study was to identify the types and relative numbers of chromosomal changes in mosquito evolution and to extend the comparison where possible to the higher diptera. To do this, we compared the enzyme linkage maps of six species of Aedes to each other and to enzyme maps of seven other mosquito species and to Drosophila melanogaster. Our results indicate that Aedes chromosomes have been modified by inversions, most which were paracentric, and by translocations, most which were Robertsonian. Intrageneric comparison of Aedes enzyme maps also revealed groups of linked enzyme loci whose integrity has been maintained throughout Aedes evolution (conserved linkages/syntenies). Intergeneric comparisons of Aedes enzyme maps with those of species in the genera Culex, Anopheles, and Toxorhynchites disclosed conserved associations of enzyme loci between mosquito genera. These findings lead us to postulate that the ancestral mosquito karyotype consisted of six chromosomal elements which, other than being combined in different ways in various mosquito groups, have remained essentially intact during mosquito evolution. Furthermore, the identification of groups of linked enzyme loci common to mosquitoes and to D. melanogaster indicates that linkage group conservation may characterize the karyotypic evolution of all dipteran insects.
几乎所有蚊子的二倍体染色体数目都是6条（2N = 6），而且它们的染色体总是中着丝粒或亚中着丝粒染色体。数目变化显然在蚊子的染色体进化中并不重要，并且由于它们染色体的形态相似性，似乎结构变化在蚊子核型进化中几乎没有发挥作用或根本没有发挥作用。本研究的目的是确定蚊子进化中染色体变化的类型和相对数量，并尽可能将比较扩展到更高级的双翅目昆虫。为此，我们将六种伊蚊的酶连锁图谱相互比较，并与其他七种蚊子的酶图谱以及黑腹果蝇的酶图谱进行比较。我们的结果表明，伊蚊的染色体已经通过倒位（大多数是臂内倒位）和易位（大多数是罗伯逊易位）发生了改变。伊蚊酶图谱的属内比较还揭示了一些连锁酶基因座组，其完整性在整个伊蚊进化过程中得以维持（保守连锁/同线基因）。伊蚊酶图谱与库蚊属、按蚊属和巨蚊属物种的酶图谱的属间比较揭示了蚊子属之间酶基因座的保守关联。这些发现使我们推测，原始蚊子核型由六个染色体元件组成，这些元件除了在不同蚊子群体中以不同方式组合外，在蚊子进化过程中基本保持完整。此外，对蚊子和黑腹果蝇共有的连锁酶基因座组的鉴定表明，连锁群保守性可能是所有双翅目昆虫核型进化的特征。
