Genetic variability and population structure of Capoeta gracilis (Keyserling 1861) populations in the southern basin rivers of the Caspian Sea as revealed by the mtDNA sequences

Abstract

This study investigated the genetic structure and diversity of Capoeta gracilis (Keyserling 1861) from the southern basin of the Caspian Sea employing cytochrome b gene sequence analysis. For this purpose, a total of 83 specimens of this species were sampled and analysed from four rivers viz., CheshmeKile, Siahrood, Tajan and ZarrinGol. Nucleotide diversity ranged from 0.00030 to 0.00715 and haplotype diversity from 0.27895 to 0.68421 for the populations studied. A total of 14 haplotypes were obtained and haplotype no. 2 was shared by all. Pairwise FST analysis showed that there was a significant genetic difference between the populations studied, with the exception of the populations living in the Siahrood and Tajan rivers. Analysis of molecular variance (AMOVA) also confirmed the genetic differentiation among populations showing 76.03% of the genetic variation within populations and 23.97% among populations (p<0.01). A selective neutrality test showed that populations of C. gracilis were probably in equilibrium and were not experiencing a population expansion. In general, it can be said that distinct populations of this species are living in the rivers of northern Iran, though further studies using other genes and molecular markers are needed to confirm the findings.