Absence of Extensive Introgression between Xenopus gilli and Xenopus laevis laevis (Anura: Pipidae) in Southwestern Cape Province, South Africa

Abstract

The evolutionary consequences of hybridization, including introgression, have been studied in many anuran amphibians (Lamb and Avise, 1986; Szymura and Barton, 1986), particularly in the African clawed frogs of the genus Xenopus (Tinsley, 1981; Kobel, 1996a; Picker et al., 1996). Species of Xenopus are found over much of sub-Saharan Africa and are mostly allopatric, though zones of sympatry and naturally occurring hybrids have been described (Picker, 1985; Tinsley et al., 1996; Yager, 1996). Although hybridization has been linked to allopolyploid speciation in Xenopus (Carr et al., 1987, Kobel, 1996b), the extent to which hybridization has facilitated genetic introgression among species has not been assessed.