Molecular phylogeny reveals cryptic diversity and swim bladder evolution of Sillaginidae fishes (Perciformes) across the Indo‐West Pacific Ocean

Abstract

AbstractAimSillaginidae is commercially exploited fish species across the Indo‐West Pacific (IWP), and changes in its abundance are of major conservation concern. Cryptic species in the marine realm emphasizes the necessity to revise our current perception of marine biodiversity, and understanding cryptic diversity is a prerequisite for sustainable development of ocean fisheries. Therefore, our goal was to provide an in‐depth understanding of cryptic diversity and evolutionary diversification of the family Sillaginidae across the IWP to assess the currently uncertain global status of the species.LocationIWP shores spanning from Japan and Australia to South Africa.MethodsSamples from 23 valid and two undefined Sillaginidae species were obtained across their habitats in IWP. Phylogenetic analyses and molecular dating of both mitochondrial (12S, 16S, Cyt b, and COI) and nucleic (RAG2) loci, combined with morphometrics of the swim bladder, were used to evaluate their cryptic species diversity and phylogeography.ResultsA total of 31 operational taxonomic units with two highly diverse cryptic complexes in Sillago ingenuua and Sillago sihama were identified across IWP, including a shallow dichotomous branch in the S. ingenuua complex and eight highly divergent clades from the S. sihama complex. The robust model‐based multigene phylogeny for 24 Sillaginidae species was well supported in accordance with the morphology evolution of swim bladder. The origin of the Sillaginidae was estimated during the Middle Eocene based on the relaxed molecular clock analysis calibrated by fossil and paleogeographic event.Main conclusionsOur results indicated that more cryptic species could be present in the family Sillaginidae and a thorough reappraisal of the current S. sihama taxonomy is warranted. The swim bladder evolution in Sillaginidae fishes was from simplicity to complex corresponding with phylogeny. Given the complex cryptic diversity of Sillaginidae species, we suggested treating them as different management units in utilization of offshore fisheries resources.