63 



and uniparens ) are considered here. Five of them are parthenogenetic, 

 and all 5 are endemic to the Trans-Pecos (northernmost) subprovince of 

 the Chihuahuan Desert. _C. neomexicanus has the lowest ecologic ampli- 

 tude of the 9, restricted to Chihuahuan desertscrub and desert riparian 

 associations between approximately 600 and 750 m. elevation. _C, exsan - 

 Ruis has the widest, occurring continuously from scrub associations at 

 approximately 550 m. to montane coniferous forest at 2000 m. There is 

 considerable overlap between the species at this ecologic scale with no 

 fewer than two occurring together in any association at any elevation 

 (and this minimum case occurs only at each extreme of the elevational 

 continuum for the genus). The Wisconsin glaciation virtually elimina- 

 ted the Trans-Pecos subprovince as a desert. The post-Wisconsin Xero- 

 thermic Period (12000-5000 years B.P.) represents an extreme in Quater- 

 nary warm arid conditions and is the most recent in an alternating ser- 

 ies between warm-dry and cool-moist Pleistocene climatic episodes. De- 

 sert biota re-invasions of the Trans-Pecos subprovince must have taken 

 place over huge areas in relatively short periods of time, perhaps ex- 

 panding 3-5 km/year, resulting in broad ecotonal herpetofaunas often 

 with species densities exacerbated by an edge effect. It is precisely 

 this complex overlapping of fluctuating ecological associations (such 

 as between desert, grassland, and pinyon-juniper woodland) that may 

 have played a criticcd role in the origin of hybrid parthenogenetic 

 Cnemidophorus . They are at present maintained in ecotonal conditions 

 resulting from these shifts. They are absent from the other subpro- 

 vinces of the Chihuahuan Desert due to historical factors and/or longer 

 climatic stability in those regions. 



170. Mosauer, W. 1932. The amphibians and reptiles of the Guadalupe 

 Mountains of New Mexico and Texas. OCCASIONAL PAPERS OF THE 

 MUSEUM OF ZOOLOGY, UNIVERSITY OF MICHIGAN, No. 246: 1-18. 



The habitats at two collecting localities. Dark Canyon and Fri- 

 jole, are described. Cnemidophorus sexlineatus sackii (= exsanguis) 

 was the most frequently seen if not the most common reptile in the 

 Guadalupe Mountains. It was very abundant at the bottom of Dark Canyon 

 but much less common on its rocky slopes. 



171. Munsey, L. D. 1972. Water loss in 5 species of lizards. COMP. 

 BIOCHEM. PHYSIOL. A COMP. PHYSIOL. 43(4): 781-794. 



Cnemidophorus tigris from the Mojave and Colorado deserts were 

 used in the experiments. Lizards were kept under (a) food only and (b) 

 no food or water conditions; tigris survived well under (a) supporting 

 the general assumption that desert lizards balance water loss with pre- 

 formed water in the diet. Water loss at 30°C. in still, relatively dry 

 air (36% R.H.) was 0.58 mg/gr/hr. The vital exsiccation limit was 

 44.91 (loss in % initial body weight). C. tigris survived an average 

 of 30 days under condition (b); one less xerically-adapted species sur- 



