Chromosomal Heteromorphism in Treron phoenicoptera

<p>Cytological studies were carried out on Himalayan green pigeon, <em>Treron phoenicoptera</em> (Columbidae : Columbiformes : Aves). Sixteen males and twelve females were sacrificed and their bone-marrow cells extracted through a sternal puncture. Cells were treated in hypotonic saline, fixed in 1:3 aceto-alcohol and stained in Giemsa. Chromosomes were classified according to Levan et al (1964).</p><p>In all, one hundred thirty three cellular plates were examined and the modal diploid count was found to be 76+3. There were seven pairs of macrochromosomes, including a pair of sex element (ZZ in case of male and ZW in case of female individuals). All, with clearly defined size and centromeric position, could be easily recognized.</p><p>A total number of thirty-one pairs formed a gradated series of elements, whose morphology could not be resolved, and have been included in the category of microchromosomes. They comprised 45.6% of TCL. Both the sex chromosomes - Z & W has centromeres at their median point, however, Z is a macrochromosome { Relative Length (LR) = 11.82% ; IC = 49.19 }, whereas, W is the largest microchromosome (LR = 6.67% ; IC = 40.45).</p><p>Among the twenty eight adult individuals examined, eight karyotypic combinations, irrespective of sex, were observed. In majority of cases, chromosome I and II had centromere in their median region. However, owing to gradual shift in the position of centromere, 8 different chromosome morphs ( Im Im IIm IIm, Im Im IIm IIst, Im Im IIst IIst, Im Ist IIst IIst, Ist Im IIm IIm, Ist Ist IIm IIm, Ist Ist IIst IIm, Ist Ist IIst IIst ) were encountered. According to Garg & Garg [1] [2] [3] [4] [5] [6] [7] [8] [9] and Garg et. al., [10] [11] [12], presence of such widespread inversion polymorphism in <em>Treron phoenicoptera</em> suggests that it may confer an adaptive advantage on the species.</p>