Study suggests the Asian arowana is the most primitive modern fish

A Malaysian-led research group from Monash University Malaysia has successfully sequenced the genome of a Malaysian fish: the Asian arowana, Scleropages formosus.

According to Prof. Christopher M. Austin, Genomics Cluster Leader at the School of Science, "The arowana belongs to a very old group of fish which you could refer to as 'living fossils'. One of the things we’re interested in is: Where does it fit in the family tree of fishes? Our study actually contradicts some views on the fish family tree.

"Every species carries its genealogical history in its DNA. Using genetic sequencing and bioinformatics methods, we can actually reconstruct the path of the evolution with considerable accuracy.

"Our study indicates that arowana is the most primitive of the modern fishes," Prof. Austin continues. "The evolutionary position of the arowana has been disputed in scientific literature — whether it’s the arowana group or the eel group that’s the most primitive form. Some recent publications suggested eels, but our publication suggests the arowana, which agrees with the more traditional scientific studies.

"Its appearance has not changed much over a very long period of geological time, and we’re talking millions and millions of years. But just because you’re primitive doesn’t mean you’re obsolete." He also cautions, "We can’t entirely say that the arowana is an all-round primitive fish because it’s not. The fact that it produces a small number of big eggs and that the males take care of the eggs is actually sort of more modern, if you like."

He likens arowanas to sharks, another fish that’s full of primitive characteristics but has survived millions of years.

This is the first Malaysian fish genome to be sequenced and the first achieved by a Malaysian university. The team hopes their work will contribute not only to evolutionary research but also to wildlife conservation in Malaysia.

The study, recently published in the journal Genome Biology and Evolution, was co-authored by Prof. Austin and Mun Hua Tan, a bioinformatician at the Genomics Facility, along with Dr. Han Ming Gan (corresponding author, research fellow and laboratory manager), Prof. Larry J. Croft (Malaysian Genomics Resources Center) and Michael Hammer (Museum and Art Gallery of the Northern Territory in Darwin, Australia).

 

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