NOTES

1. It must be admitted that the degree of genetic isolation between many of the populations listed is not known. Hybrids between some of them have been found in nature, and, at least in the morabines, the hybrids are sometimes largely fertile in laboratory crosses. However, as Hall and Selander (1973) have shown in the Sceloporus grammicus complex, genetic isolation may still be complete, even in cases of apparently free hybridization and good hybrid fertility, probably because of recombinational breakdown in the backcross generation, serves as a barrier to gene flow between the pure populations. Until similar genie data are available for the examples cited or for comparable cases, these can only suggest patterns. It should also be noted that I do not always interpret published data the same way as do their authors. [back]