Genetic diversity and population structure of the upriver orange mangrove Bruguiera sexangula along the coastlines of Thailand

Abstract

Upriver orange mangrove Bruguiera sexangula is a member of the Rhizophoraceae family and is usually distributed in the intertidal zones of the tropical and subtropical coastal areas. The analyses of genetic diversity and population structure of B. sexangula are essential for their conservation and management. In the present study, the genetic diversity and structure of 101 B. sexangula individuals from mangrove forests in Thailand were evaluated using single nucleotide polymorphisms (SNPs) through restriction site-associated DNA sequencing (RAD-seq). A total of 3482 high-quality SNPs were obtained after filtration for genetic study. All 3 genetic structure analyses (Bayesian analysis, principal components analysis, and maximum likelihood tree) revealed that these individuals can be clustered into 2 groups corresponding to geographical regions, namely the Andaman Sea and Gulf of Thailand. The level of genetic differentiation between the clusters was moderate (FST = 0.122, p < 0.001), and the analysis of molecular variance (AMOVA) indicated that the individual differences within groups were greater than the differences between the 2 groups. A moderate level of genetic diversity (Shannon's information index, I = 0.458; observed heterozygosity, Ho = 0.416; expected heterozygosity, He = 0.295) of B. sexangula was observed. These results give us a better understanding of the genetic variations and will provide a framework for the conservation of B. sexangula.