86 



236. Wever, E. G. 1967. The tectorial membrane of the lizard ear: 

 species variations. JOURNAL OF MORPHOLOGY 123(^): 355-372. 



A complete type of tectorial membrane is found in the lizard 

 Cnemidophorus tesselatus . A photomicrograph of the inner ear is 

 presented and a complete description of the tectorial membrane and 

 its relation to other inner ear structures is given. 



237. Whitford, W. G. and F. M. Creusere. 1977. Seasonal and yearly 

 fluctuations in Chihuahuan Desert lizard communities. HERPETOLOGICA 

 33(1): 54-65. 



Cnemidophorus exsanguis , _C. inornatus, C_. tesselatus and _C. tigris 

 marmoratus were part of a community studied in 4 habitat types of a Chi- 

 huahuan Desert watershed. _C. tesselatus and _C. tigris were permanent 

 residents of open Larrea and yucca-mesquite -Ephedra habitats and trans- 

 ients in playa grassland habitat and arroyo shrub associations. _C. ex - 

 sanguis was an immigrant from montane habitats into playa grassland and 

 yucca-mesquite -Ephedra habitats, as was _C. inornatus , which was also 

 present as a transient resident. Cnemidophorus tigris populations fluc- 

 tuated markedly, showing a doubling in density in certain years. In- 

 creased rainfall and food availability resulted in larger clutch sizes, 

 increased survivorship of hatchlings and recruitment of young into the 

 population. Playa and bajada populations exhibited some seasonal cyclic 

 differences; bajada population levels also tended to fall more quickly 

 after an opportunistic increase. Cnemidophorus tesselatus populations, 

 however, exhibited very little fluctuation in densities over the 5 years 

 encompassed by this study, remaining at all times at a much lower level 

 than those of _C. tigris . Adults and hatchlings of both species exhibit- 

 ed varying degrees of allochronic seasonal activity based on food avail- 

 ability and abundance. The playa acts as a "cold-air sink", delaying 

 spring emergence of lizards 3-4 weeks behind those on the bajada. Over- 

 all lizard species diversity for a given year was correlated with the 

 previous 2 years rainfall. 



238. Wiley, E. O. 1978. The evolutionary species concept reconsider- 

 ed. SYSTEMATIC ZOOLOGY 27(1): 17-26. 



Problems concerning the use of the species concept in different 

 ways by biologists with diverging viewpoints (i.e. ecologists and evo- 

 lutionists) are discussed. Simpson's definition of the 'evolutionary 

 species' is modified to "a species is a lineage of ancestral-descendant 

 populations which maintains its identity from other such lineages and 

 which has its own evolutionary tendencies and historical fate". The 

 application of the evolutionary species concept to allopatric demes and 

 to asexual species is discussed. It is concluded that the lack of evo- 

 lutionary divergence forms the basis for grouping such populations into 

 single species (i.e. all _C. tesselatus clones belong to a single spe- 



