Genetic diversity of the cytochrome b gene in common carp (Cyprinus carpio) between wild and Pool-breeding in Basra Governorate, Iraq

et al. Awad

Authors

Noor M. Awad Unit of Aquaculture, College of Agriculture, Basrah University

Keywords:

Common carp, cytochrome b, genetic diversity, nucleotide diversity, phylogenetic tree, genetic polymorphism.

Abstract

Common carp (Cyprinus carpio) is one of the most economically important fish species in both the wild fishing and aquaculture sectors. This study aimed to evaluate the genetic variation and polymorphism of common carp (Cyprinus carpio) populations in both wild and farmed environments in Basra Governorate. The cytochrome b (Cyt b) gene, encoded in mitochondrial DNA (mtDNA), was used as a precise genetic marker. Laboratory work involved collecting samples from both environments, extracting the DNA, amplifying the Cyt b gene using polymerase chain reaction (PCR), and then analyzing the sequence. The results showed similarly high levels of haplotype diversity (Hd= 0.768 for wild and 0.790 for basins), coupled with balanced and convergent nucleotide diversity (pi = 0.0495 for wild and 0.04818 for basins) across the 394-base-pair gene locus. The haplotype network revealed a dominant major gene cluster comprising haplotypes (H1, H3, H4, H5, H7), while haplotypes (H2, H6) formed separate maternal lines separated by several mutational steps. Regarding tests of neutrality and ethnogeography, the results showed demographic stability and overall neutral evolution. Tajima’s D test recorded positive but not statistically significant values, while Fu’s Fs test recorded sharp and highly significant negative values (P < 0.001), confirming the presence of an excess of rare genotypes and the stability of the effective population size (Ne) without experiencing severe demographic collapses despite environmental pressures. AMOVA analysis and genetic differentiation values (FST / ΦST = -0.028) also revealed a complete absence of genetic structure and differentiation between wild-caught and pond-caught fish, reflecting a high and preserved genetic diversity among the common carp populations in Basra Governorate.

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