Investigation of the Possible Hybridization of Alligator Gar With Longnose and Spotted Gar

Twelve alligator gar (Atractosteus spatula) with unusual morphology from several locations across Texas were identified and genotyped to investigate the possibility of hybrid ancestry. Hybridization is a possibility since in a large part of their range, alligator gar are sympatric with both longnose gar (Lepisosteus osseus) and spotted gar (L. oculatus). Furthermore, hybridization between alligator gar and longnose gar has been documented in captivity. Individuals were genotyped for a mitochondrial locus (ND5), two nuclear intron loci (RAG1 and S7), two nuclear exon loci (Enc1 and Sreb2), and nine microsatellite loci. Several individuals showed mixed ancestry, including four apparent F1 alligator/longnose gar crosses. All hybrid individuals showed alligator gar mitochondrial haplotypes. These results suggest that hybridization between alligator gar and other species of gar does occur in their natural habitats with a strong trend for hybridization between female alligator gar and male gar of another species. While alligator gar abundance has declined in much of their range, longnose gar and spotted gar have remained relatively abundant, which suggests that hybridization could be a factor in alligator gar conservation.