Mitochondrial Dna Variation And Maternal Lineage Of Indigenous Goat Breeds In Narok And Isiolo Counties Of Kenya

Abstract

The aim of this study was to ascertain the mitochondrial DNA genetic variation and the possible maternal lineage of domestic goat populations in Narok and Isiolo Counties in Kenya. For this purpose, we determined the sequence of the mitochondrial DNA (mtDNA) cytochrome b in 30 goat samples from each of the two regions, and compared with 22 known sequences of goat cytochrome b. Eighty two variable sites found in a 944 bp sequence of cytochrome b (Cyt b), and 34 Cyt b haplotypes were subsequently defined. Only two haplotypes, (Hap 12 and Hap 13) were shared between populations. The phylogeny analysis by means of the neighbor-joining tree based on Kimura 2-Parameters of these sequences in combination with goat Cyt b sequences from GenBank showed that all goat sequences were clustered into two groups (A and G) as previously described. It appeared that in these domestic goats, haplogroup A was dominant and distributed in both populations, while haplogroup G was only found in a few samples. The overall haplotype diversity and nucleotide diversity indices were 0.981±0.006 and O.019±0.001 respectively. A very high percentage (99.62%) of the genetic variation was distributed within the regions and a smaller percentage (0.38%) distributed among regions as revealed by the analysis of Analysis of Molecular Variance (AMOVA). Population expansion analysis based on mismatch distribution and Fu's Fs statistic indicate that two expansion events in these goats occurred respectively at about 10 and 30 mutational time units ago. The results of this study show that there is no significant geographical structurization in Narok and Isiolo Goat populations, which suggested that there existed strong gene flow among goat populations probably caused by extensive transportation of goats in history and similar maternal lineages between the two regions.