Drosophila mediopunctata belongs to the tripunctata group, and is one of the commonest Drosophila species collected in some places in Brazil, especially in the winter. A standard map of the polytene chromosomes is presented. The breakpoints of the naturally occurring chromosomal rearrangements are marked on the map. The distribution of breaking points through the chromosomes of D. mediopunctata...

ATURAL populations of many species of Drosophila show chromosomal N p o l ymorphisms, maintained presumably by superior fitness of the heterokaryotypes. Because inversions suppress the recombination in structurally heterozygous chromosomes, they may keep together the coadapted gene complexes inside, and in the vicinity of the inverted sections. This view is supported by the €act that in experim...

HE adaptive importance of chromosomal polymorphism in Drosophila has T been demonstrated through analysis of natural populations as well as through experiments in the laboratory (c j . DOBZHANSKY 1951; PATTERSON and STONE 1952; DA CUNHA 1955). However, in different species the genetic variability takes different forms, and chromosomal inversions are characteristic of the adaptive polymorphism i...

Adaptation is defined as an evolutionary process allowing organisms to succeed in certain habitats or conditions. Chromosomal inversions have the potential to be key in the adaptation processes, since they can contribute to the maintenance of favoured combinations of adaptive alleles through reduced recombination between individuals carrying different inversions. We have analysed six genes (Pif...

H E two preceding papers of this series have described the effects of near T infrared radiation (A ca. 10,000 h;) and of ultraviolet radiation (A 2,537 8) in modifying the frequency of chromosomal rearrangements induced by X-ray treatment of the spermatozoa of Drosophila naelanogaster (KAUFMANN, HOLLAENDER, and GAY 1946; KAUFMANN and HOLLAENDER 1946). In the course of the first series of experi...

In contrast to Drosophila melanogaster and Drosophila simulans, the yellow (y) gene region of Drosophila subobscura is not located in a region with a strong reduction in recombination. In addition, this gene maps very close to the breakpoints of different inversions that segregate as polymorphic in natural populations of D. subobscura. Therefore, levels of variation at the y gene region in this...

Drosophila subobscura is a Palearctic species that has recently colonized the Americas. It was first found in 1978 in Puerto Montt, Chile, and in 1982 in Port Townsend, WA. The colonization and rapid expansion of the species in western South and North America provides distinctive opportunities for investigating the process of evolution in action. The inversion polymorphism in the O chromosome f...

background: approximately 205 million pregnancies occur each year in the worldwide. on the other hand, spontaneous abortion has been reported in 15-20% of all diagnosed pregnancies. the most common cause of spontaneous abortion is chromosomal abnormalities of the embryo. robertsonian translocation carriers specially 21-14 are the most common balanced rearrangement among the carrier couples with...