Tuesday, 8 March 2016

Genome of the spotted gar

Spotted gar (Lepisosteus oculatus)
Brian Gratwicke  CC BY 2.5 (Wikimedia Commons)
Not all bony fish are teleosts. Teleostei is an infraclass of ray-finned fish (Actinopterygii) with bichirs, sturgeons and gars (some 50 species) all basal to to the more numerous teleosts (some 30,000 species). The phylogeny of bony fishes has been largely resolved by Near et al. (open access).

Alligator gar (Atractosteus spatula) Moon Lake, Mississippi. March 1910, Photographer D. Franklin,
American Museum of Natural History (public domain)
Romer's Man and the Vertebrates did not make much of garpikes, but did include a great photo (shown above) of the largest species. My yellowing copy predates the genetic code yet alone genomics.

What we now know is that teleosts are characterized by the Teleost Gene Duplication (TGD). This event was followed by rapid sequence evolution that may explain their success as a group. It can, however, make it difficult to identify orthologs to tetrapod genes and frustrate interpretation of data obtained in zebra fish (Danio rerio). To provide a bridge, Braasch et al. have sequenced and have just published the genome of the spotted gar (open access).

To my knowledge no living species of the gar family is viviparous.

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