Genetic Structure and Biogeography of Asian Arowana (Scleropages formosus) Determined by Microsatellite and Mitochondrial DNA analysis

Abstract

The Asian arowana (Scleropages formosus) is distributed in Southeast Asia and highly endemic to many river systems. Genetic structure of five strains of arowana was assesed. Twenty-nine microsatellite loci were screened to assess the short-term genetic differentiation. Sequences of ATPase subunit 6 and 8 were obtained to estimate the time of divergence. Microsatellite data yielded high value of F ST between each strain. The gene tree constructed based on microsatellite data shows that the Asian arowana is a monophyletic group with two lineages. The green arowana is the outgroup and has a closer relationship with Indonesian gold arowana. All the haplotypes had unique ATPase sequences. Sequences of the ATPase gene of the arowana were not as variable compared with microsatellites. The mtDNA data yielded a gene tree of different topology as compared to that obtained from microsatellites. The arowana consists of a monophyletic group of mtDNA with three different lineages which represent three different colors red, green and gold. The red arowana is the outgroup but phylogeny was not fully resolved for the gold strains. The phylogenetic structure derived from mtDNA is however not associated with geographical regions. The divergence of the different color strains of arowana was backdated to between the late Pliocene to late Pleistocene era. It is believed that the arowana dispersed in Southeast Asia when Sundaland was formed. The fluctuation of sea level during Pleistocene separated the Indonesian islands with the Southeast Asian mainland and caused the arowana to diverge into distinct strains.