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      https://www.ias.ac.in/article/fulltext/jgen/089/02/0173-0182

    • Keywords

       

      karyotype variation; queenless ponerine ants; speciation; Diacamma.

    • Abstract

       

      The queenless ponerine ant Diacamma ceylonense and a population of Diacamma from the Nilgiri hills which we refer to as ‘nilgiri’, exhibit interesting similarities as well as dissimilarities. Molecular phylogenetic study of these morphologically almost similar taxa has shown that D. ceylonense is closely related to ‘nilgiri’ and indicates that ‘nilgiri’ is a recent diversion in the Diacamma phylogenetic tree. However, there is a striking behavioural difference in the way reproductive monopoly is maintained by the respective gamergates (mated egg laying workers), and there is evidence that they are genetically differentiated, suggesting a lack of gene flow. To develop a better understanding of the mechanism involved in speciation of Diacamma, we have analysed karyotypes of D. ceylonense and ‘nilgiri’. In both, we found surprising inter-individual and intra-individual karyotypic mosaicism. The observed numerical variability, both at intra-individual and inter-individual levels, does not appear to have hampered the sustainability of the chromosomal diversity in each population under study. Since the related D. indicum displays no such intra-individual or inter-individual variability whatsoever under identical experimental conditions, these results are unlikely to be artifacts. Although no known mechanisms can account for the observed karyotypic variability of this nature, we believe that the present findings on the ants under study would provide opportunities for exciting new discoveries concerning the origin, maintenance and significance of intra-individual and inter-individual karyotypic mosaicism.

    • Author Affiliations

       

      Nutan Karnik1 H. Channaveerappa2 H. A. Ranganath3 4 Raghavendra Gadagkar1 5

      1. Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560 012, India
      2. Maharani’s Science College for Women, J. L. B., Mysore 570 005, India
      3. Department of Studies in Zoology, University of Mysore, Manasagangotri, Mysore 570 006, India
      4. National Assessment and Accreditation Council, P. O. Box 1075, Nagarbhavi, Bangalore 560 072, India
      5. Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India
    • Dates

       
  • Journal of Genetics | News

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