Hybridization between Longnose and Alligator Gars in Captivity, with Comments on Possible Gar Hybridization in Nature

Abstract

AbstractAlthough hybridization occurs widely in fishes, it has never been recorded in gars. Here, we describe the first known hybrids of the longnose gar Lepisosteus osseus and alligator gar Atractosteus spatula from four specimens spawned in an aquarium containing multiple gar species. Genetic analyses of cytochrome b and tyrosinase sequences and a microsatellite locus indicated that the four specimens were hybrid offspring of a female longnose gar and a male alligator gar. The combination of physical appearance, meristic counts, and mensural measurement ratios further discriminated the hybrids from each parent and supported the conclusion of hybrid origin. The four hybrids had body coloration and transverse scale rows similar to those of longnose gar, a snout length and shape intermediate between those of longnose and alligator gars, and two rows of teeth on the upper jaw as are seen in alligator gar. This conclusive evidence of intergeneric hybridization in the gars may provide insights into phylogenetic relationships in Lepisosteidae and hybridization theory and may explain unsubstantiated reports of gar hybridization in nature and the pet trade.