Chromosomal Garniture of Emberiza melanocephala

The Black-headed Bunting, Emberiza melanocephala, is a passerine bird in the bunting family Emberizidae, a group now separated by most modern authors from the finches, Fringillidae. Its natural food consists of insects when feeding young, otherwise seeds.

The Black-headed Bunting breeds in southeast Europe, east to Iran, and migrates in winter mainly to India, with some individuals moving further into Southeast Asia. Black-headed Bunting breeds in open scrubby areas including agricultural land during summers and builds nest in a low bush or on the ground. The nest is a cup made of dry grass, lined with hair. The clutch consists of 4-6 eggs.

This bird is 17 cm long with a long-tail. The breeding male has bright yellow underparts, chestnut upperparts and a black hood.

One male and one female individual yielded sixteen well spread metaphase plates. The diploid chromosome count varied from 78 to 86 with most prominent peak at 82 which has been taken as the diploid chromosome number of this species.

On arranging the chromosomes into morphologically similar pairs, little variation was noticeable within the chromosomes. There was a steady decline in size, so much so, that it was difficult to demarcate the chromosomes into two conventional categories. However, applying the concept given by De Boer (1976), eight pairs of chromosomes contributing ≥ 2.5% of total chromosomal length had been differentiated as macrochromosomes.

On the basis of protocol suggested by Garg ^[2-5]; Garg & Garg ^{[1] [6–15]}; Garg, Jain & Garg ^{[16] [17]}; Garg & Shrivastava ^[18-26]; Garg, Bharadwaj & Garg ^[27] and nomenclature proposed by Levan, the macrochromosome were classified into two groups : Group I had two pairs of chromosomes comprising autosomal elements (Chromosome 1 and 2) - all had centromeres in their median county. Chromosome 1 is the largest element of the set being 4.04µ long, making up 16.13% of the total macrochromosomal length. Chromosome 2 was 3.36 µ long.

Group II consisted of six chromosomes (chromosomes 3, 4(Z-W), 5, 6, 7 and 8) with sub-terminal centromere. The Z-chromosome was a little short of length than chromosomes 3 with an absolute length of 2.73µ. Though W was a large chromosome as regard to its share in total macro-chromosomal length, yet it is the smallest element among macrochromosomes. It has a terminal centromere constituting 7.81% of TML.

The remaining thirty three pairs of chromosome, that contributed more than half of the total chromosomal length and strewn all over the genome, were placed in the category of microchromosomes, as none of them shared ≥ 2.5% of TML individually.