Extreme chromosomal polytypy in a population of Sceloporus grammicus (Sauria:Phrynosomatidae) at Santuario Mapethé, Hidalgo, Mexico

Abstract

The karyotypic status of the mesquite lizard, Sceloporus grammicus, was investigated at two localities at Santuario Mapethe, Hidalgo, Mexico. A total of 23 different karyotypes was recorded freom the 36 individuals examined. individual lizards were heterozygous at up to four chromosomes. Karyotypic differences were attributed to Robertsonian fission/fusions and pericentric inversions involving the macrochromosomes. The polymorphisms generally conformed to HardyWeinberg equilibrium suggesting a lack of underdominance for most rearrangements. The extreme chromosomal polytypy observed at Santuario Mapethe is hypothesized to result freom parapatric hybridization between two chromosome races.