Mitochondrial D-Loop Diversity and Morphometric Differentiation Among Plumage Phenotypes of Nigerian Local Chickens
Nigerian indigenous chicken populations carry adaptive genetic variation accumulated over centuries of natural and farmer-driven selection, and that variation is most visible in five widely recognized plumage types: Naked Neck, Frizzle feather, Normal feather, Feathered shank, and Crested. One hundred birds of five different feather types were sampled in Kwara State, Nigeria and ten morphometric linear body measurements was recorded for each bird. Blood was drawn for DNA isolation, after which the displacement loop was amplified with chicken-specific primers and sequenced in a subset of 15 birds, three per phenotypes. The results shows that Males and females differed significantly in body height (p = 0.007), body length (p = 0.001), drumstick length (p = 0.005), and shank diameter (p = 0.002). Naked Neck birds recorded the largest body dimensions on most traits and Frizzle birds the smallest. Feather type separated the groups most sharply on keel length, where Naked Neck birds (18.99 cm) exceeded Crested birds (9.35 cm) by 103.1 percent. The 15 sequences resolved six haplotypes across four polymorphic sites, giving moderate haplotype diversity (Hd = 0.819 ± 0.064) on a low nucleotide diversity of π = 0.00213 per site. Neutrality statistics gave no signal of recent expansion or selection. All five phenotypic groups warrant conservation, and the nuclear architecture underlying them warrants mapping.
Keywords: mitochondrial D-loop; Nigerian indigenous chickens; genetic diversity; plumage phenotypes; haplotype diversity; haplogroup D; conservation genetics
