Karyology of a few species of south Indian acridids .2. Male germ line karyotypic instability in Gastrimargus

Gastrimargus africanus orientalis, an acridid grasshopper has revealed the existence of karyotypic mosaicism in the male germ line cells of a few individuals with 2n = 23, 19, 21, 25 and 27 chromosomes. Details of this chromosomal instability are presented in this paper

Estimation of inter‐genotypic competitive ability of the parental races (Drosophila nasuta nasuta and D. n. albomicana) and of the newly evolved Cytoraces (I and II)

Interracial hybridization between D.n. nasuta (2 n = 8) and D. n.albomicana (2 n = 6) resulted in the formation of two new karyotypic strains denoted Cytorace I and Cytorace II. The karyotypes of each of these Cytoraces include chromosomal elements from both parental races (RAMACHANDRA and RANGANATH 1986a). The parental strains and the newly formed Cytoraces I and II were subjected to interspecific competition. The results reveal that all four experimental strains were competitively superior to the D. melanogaster tested strain. The study indicates certain degree of Cytogenetic divergence between parental and newly evolved genomes

Karyotype differentiation among members of the immigrans species group of Drosophila

Karyotypes of ten species belonging to four of the five subgroups of the immigrans species group of Drosophila were examined. The group includes species with the most primitive form of karyotype as well as species with so-called recent karyotypic configurations. It is an assemblage of species with karyotypes representing five of the six successive stages involved in the evolution from 2n = 12 to 2n = 6. Implications of these findings are discussed

The chromosomes of three species of the Montium subgroup of Drosophila

Chromosomes of Drosophila truncata, D. nagarholensis, and D. agumbensis of the montium subgroup were analyzed to record the divergence attained at the level of metaphase complement and the extent of inversion polymorphism. Results are presented in this article

Evolution of a new chromosomal lineage in a laboratory population of Drosophila through centric fission

Structural rearrangements of chromosomes have played a decisive role in the karyotypic evolution of species. It is also known that inversions, translocations, fusions, fissions, heterochromatin variations and other chromosomal changes occur as transient events in natural populations. Herein we report the occurrence of a rare event of centric fission of a metacentric chromosome in a laboratory population of Drosophila, called Cytorace 1. This centric fission has been fixed in a sub-population of Cytorace 1, resulting in a new chromosomal lineage called Fissioncytorace-1