HAEMOGLOBIN TYPES DISTRIBUTION AND NUCLEAR CYP2U1 GENE EFFECTS ON GENETIC DIVERSITY OF NIGERIAN LOCAL CHICKENS WITH DIFFERENT PLUMAGE TYPES
Nigerian indigenous chickens (Gallus gallus domesticus Linnaeus, 1758) are invaluable genetic resources that have evolved adaptive traits suited to diverse tropical environments, yet the molecular genetic basis of their phenotypic diversity remains underexplored. This study examined the distribution of hemoglobin (Hb) and CYP2U1 gene polymorphism as complementary markers of genetic diversity among five plumage- phenotype groups, namely normal feathered, naked neck, frizzle feathered, feathered shank (ptilopody), and crested, in local Nigerian chickens from Kwara State, Nigeria. Hemoglobin typing was performed using cellulose acetate electrophoresis. A 747-bp region of the CYP2U1 gene was amplified from extracted genomic DNA. Population and molecular genetic analyses were done using POPGENE 1. 32, DnaSP v 6. 12. 03, and MEGA 11. Three hemoglobin genotypes (HbAA, HbAB, HbBB) were found in all plumage- type populations, and the overall allele frequencies were 0. 46 for allele A and 0. 54 for allele B. HWE in the feathered shank population was near perfect (0. 0.945), whereas the crested population showed a significant heterozygote deficiency (0. 072), indicative of likely inbreeding. The frizzle population showed a high level of heterozygosity, indicative of recent admixture or a heterozygote advantage. CYP2U1 sequencing identified 13 polymorphic sites, 9 haplotypes with high haplotype diversity (Hd = 0. 848 ± 0. 088), and low- to- moderate nucleotide diversity (π = 0. 00352). An exactly conserved domain between sites 203–388 was found in all plumage populations. Pairwise genetic identities (Nei, 1972) ranged from 0. 833 (frizzle–feathered shank) to 0. 961 (feathered shank–crested), with an overall FST of 0. 15, suggesting a moderate level of genetic subdivision. These findings confirm moderate genetic diversity in Nigerian indigenous chickens and demonstrate that combined hemoglobin typing and CYP2U1 gene analysis could provide effective tools for breed characterization, inbreeding detection, and conservation planning in indigenous Nigerian poultry.
Keywords: Haemoglobin polymorphism, Nuclear CYP2U1 gene, Genetic diversity, Nigerian indigenous chickens.
