Hybrids of Two Parthenogenetic Clonal Complexes and a Gonochoristic Species of Cnemidophorus, and the Relationship of Hybridization to Habitat Characteristics

Cnemidophorus laredoensis comprises two allodiploid parthenogenetic clonal complexes. LAR-A(2n) includes C. laredoensis as originally described from Laredo and many recently discovered populations in other parts of Texas and Mexico. LAR-B(2n), discovered in 1984, also has been recently reported from both sides of the Rio Grande, including many sites here LAR-A(2n) does not occur. Seven hybrid female and 16 hybrid male LAR-A(2n) x C. gularis (gonochoristic) were collected at 11 sites in Texas and Mexico; three hybrid female LAR-B(2n) x C. gularis were collected at three sites in Texas and Mexico. All hybrids were distinguishable on the basis of color pattern and scutellation. Also, two unusually large females exhibited the effects of heterosis in body size, and one putative hybrid captured alive was triploid. Cytogenetic and/or behavioral mechanisms in LAR-B(2n) are apparently more resistant to hy- bridization than in LAR-A(2n) under identical habitat conditions. The production of hybrids, especially those of LAR-A(2n) x C. gularis, is closely related to disturbed habitat structure and/or relative abundance of syntopic whiptail forms, allowing increased contact between the parental forms. Hybrid LAR-A(2n) x C. gularis were most often found at sites where confined space intensified the interactions between the parental forms, at sites where large numbers of male C. gularis came into contact with the few female LAR-A(2n) present, and at sites where large numbers of female LAR-A(2n) came into contact with the few male C gularis present.