5tf- 



SYSTEMATIC ZOOLOGY 17: 219-231. 



The systematic treatment of uniparental species is reviewed. 

 They are and have been recognized using all criteria that have been 

 applied to bisexual species (i.e. morphology, ethology, occupying a 

 distinct niche, having geographic range), with genetic isolation of 

 the species gene pool implicit. This logically implies, however, that 

 interbreeding must be able to take place between individuals of that 

 species, therefore the classic species definition is inadequate for 

 parthenoforms. The author favors the Simpsonian evolutionary species 

 concept. Clonal variability within a unisexual "species" is pointed 

 out, and it is suggested that formally naming such makes no more sense 

 than naming genetic strains of laboratory animals or variants in a sta- 

 ble polymorphic species. It is possible that repeated hybridizations 

 between the same two species could give rise to genetically different 

 clones (this, in fact, has almost certainly occurred in Cnemidophorus 

 tesselatus ) and that these new gene combinations could be operated on 

 effectively by natural selection without being swamped out, but the 

 author does not favor giving each such clone specific rank. Hybrid 

 parthenoforms will not be genetically adapted to any one habitat or 

 niche and can readily make use of niches, often man-made, that are not 

 occupied, or that are not too firmly occupied. They cannot compete 

 where another species is well entrenched and an integral part of a 

 stable community. 



l'^6. — . 1971a. Conclusive evidence of parthenogenesis in three spe- 

 cies of Cnemidophorus (Teiidae). COPEIA 1971(1): 156-158. 



Cnemidophorus neomexicanus , _C. tesselatus and _C. uniparens were 

 raised through 3 generations in the laboratory. All offspring were 

 produced without benefit of paternal fertilization and all were female. 



1*7. — . 1971b. Parthenogenesis in reptiles. AMERICAN ZOOLOGIST 

 11(2): 361-380. 



A general review article, discussing origins, evolution, genetics 

 of parthenogenesis, nomenclatural and systematic problems, and the oc- 

 currence of males. 8 male Cnemidophorus tesselatus had been collected 

 from the vicinity of Presidio, Texas, as of June 1968. The chief ad- 

 vantage to parthenogenesis is the ease of colonization of new habitats. 

 Evidence exists that an optimum density threshold must be passed before 

 a parthenogenetic population becomes stable; this implies that single 

 individuals do not found populations. Heavy collecting and commercial 

 alteration of habitat wiped out populations of _C. exsanguis and _C. tes - 

 selatus , respectively. Hybrid parthenospecies are in a sense preadap- 

 ted because they are not fixed genetically by past selection, although 

 further selection is still possible. Their richer genetic complexion 

 could compensate for their reproductive rigidity. Those that reproduce 



