Abstract
The karyotypes of 94 species of Indian ants were examined. Their chromosome numbers range almost continuously between n=5 and 38, though the frequency distribution is bimodal with a remarkable antimode at n=11 and two modal points at n=10 and 15. Based on this bimodal distribution, Indian ants were classified into two groups: Lower-numbered species (n≤11) and higher-numbered species (n>11), the former being characterized by metacentric -rich karyotypes, and acrocentrics predominate in the latter. The three major subfamilies (Ponerinae, Myrmicinae, and Formicinae) showed a highly divergent distribution in chromosome number, ranging between n= 7-38, 6-35, and 8-27, respectively, suggesting a convergence in karyotype evolution of each subfamily, Another three subfamilies, of which only a few species were examined, had moderate or lower numbers, i.e., n=5-14 in Dolichoderinae, n=14 in Cerapachyinae, and n=12 in Dorylinae. We found four Robertsonian polymorphisms, two pericentric inversion polymorphisms, and four reciprocal translocations, three of which were fixed. Robertsonian polymorphisms were found only in higher-numbered species, while translocations were restricted to lower-numbered species. A possible biological significance for this nonrandom distribution of rearrangements is discussed with reference to karyotype evolution in ants.
