Genetic Diversity and Population Structure of Three Caranx Species from Batangas Province, Philippines

Abstract

Species belonging to the genus Caranx, locally known as “talakitok,” belong to the economically important fish in the Philippines. The popularity of these species makes them prone to overexploitation, which may result to a decline in their population in the wild. Despite these circumstances, stock assessment and population genetic variation studies are scarce. In this study, three species from this genus (C. ignobilis, C. papuensis, C. ignobilis) from the Batangas region were subjected to genetic diversity and population structure analyses using the cytochrome b (cyt b) gene of the mitochondrial DNA (mtDNA) to address these information gaps. High haplotype and high nucleotide diversity were noted in C. ignobilis, which may indicate that the population is still large and stable. However, C. papuensis and C. sexfasciatus populations had a low nucleotide diversity and high haplotype diversity, which could mean a possible genetic bottleneck in the recent past. Likewise, each of these three species showed no genetic differentiation between marine and freshwater specimens, which can be attributed to their life history and biology. Analysis of molecular variance (AMOVA) revealed weak genetic structure, indicated by low percentage value between populations. Based on neutrality tests and mismatch distribution analysis, the three species may have possibly undergone demographic expansion. This study provides the genetic profile of Caranx species found in the Batangas region before the recent Taal Volcano eruption (January 2020), which can be used to investigate the effects of this eruption on the population of this species. Likewise, results obtained from this study served as preliminary data for the population genetics of Caranx spp. found in Batangas, Philippines.