| 
  • If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • Stop wasting time looking for files and revisions. Connect your Gmail, DriveDropbox, and Slack accounts and in less than 2 minutes, Dokkio will automatically organize all your file attachments. Learn more and claim your free account.

View
 

Cnemidophorus tigris, Western Whiptail

Page history last edited by PBworks 13 years ago

 Cnemidophorus tigris, Western Whiptail

   (Also known as Aspidoscelis tigris)

 

 Animalia: Reptilia: Squamata: Reptilia: Teiidae: Cnemidophorus: tigris

 

             

     C. tigris, Western Whiptail. photograph courtesy of Robert Shantz

 

Morphology: Cnemidophorus tigris are relatively small squamates, only about 2-6 inches in snout-to-vent length. Distinguishing characteristics include a forked chemoreceptive tongue, pointed snout, triangular head, spotted, and "tiger-like" markings. Another identifying characteristic of C. tigris is its gait -- some subspecies have a 'jerking' gait, but all place their hind feet in front of their fore feet when walking. The most noted trademark of C. tigris, however, is its long, thin tail, which can be up to twice as long as its torso if it has never had to lose and regenerate it due to predation.

     Colors in C. tigris tend to run from bright blue-greens in juveniles to dull browns, blacks, and yellows in adults. These vary between subspecies and tend to become less saturated with age. Also, elevation has been shown to be proportionally related to increased melanism. Dorsal scales are small, granular, and generally dark-colored. The ventral scales are larger, with a flat, square appearance and white coloration, running in eight rows from snout-to-vent. Keeled scales run down the length of the limbs, as suggested by the genus name (Greek; knemidos ="greaves," phoros="wearing").

 

Distribution: The Cnemidophorus genus of squamates is located wholly in the New World, with the Cnemidophorus tigris being found in parts of New Mexico, Arizona, California, Utah, Oregon, Southwest Idaho, and West Texas. 17 subspecies habitate various regions, with A.t. tigris being the only subspecies habitating Idaho. Globally, they are secure in their population, but in Idaho, there is a concern about long-term decline. 

     Region of habitation for the Great Basin Western Whiptail, C.tigris. Image courtesy of NatureServe Explorer

 

Habitat: Most species of whiptail lizards inhabit arid, dry regions. Their preferable habitatats are grasslands and deserts, where they take up residence in the abandoned burrows of mice, rats, and other lizards. Sagebrush, sedges, grasses, and other low-lying plants are the favored vegetation for the lizards to hunt in and around, as well as take temporary shelter from predators. While they do sun themselves, it has been found that large or flat rocks in the environment is not as important as soft earth for burrows, and that C. tigris tends not to use large, open rocks for sunning, even when present.

 

 

     C. tigris, Western Whiptail. Photograph courtesy of Robert Shantz

 

Reproduction: Some hybrid species of the Cnemidophorus genus have evolved the usage of parthenogenesis. However, C. tigris tends to be bisexual, with very little dimorphism between sexes. It is suggested, however, that the different unisexual species of whiptails came from various hybridizations of bisexual species, the parthenogenic capability evolving due to environmental stress, since all species of unisexual whiptails inhabit harsh desert habitats. Whiptails in general tend to lay smaller clutches, yet larger eggs, than iguanids of similar size. Females may produce more than one clutch per reproductive season; however, this depends on subspecies.

 

Behavior and Diet: The majority of whiptails happen to be diurnal, with most being active in the morning and seeking shelter in the afternoon. The Western Whiptail is primarily an insectivore, feeding on various types of arthropods, such as beetles, ants, butterflies, and grasshoppers in the morning and early afternoon after sunning itself. The species is also known to feed on scorpions, spiders, and other small lizards. Whiptails use their jaws instead of tongue to capture their prey, like most other scleroglassans (Meyers & Herrel, 2003). Also, Western Whiptails are active predators, hunting their prey in approximately a .1-.3 hectare home range.

    C tigris both hibernates and aestivates, though latitude and seasonal differences between various parts of the Western US tend to affect different populations. C.t. tigris is usually active by mid-April in Idaho, but aestivates during the summer, becoming more active in the early fall until late fall.  

 

Study of Interest:

Taylor, Harry; Harris, L; Burkholder, G; Walker, J. Relationship of Clutch Size to Body Size and Elevation of Habitat in Three Subspecies of the

       Teiid Lizard, Cnemidophorus tigris. The Southwestern Naturalist, Vol. 1994, No. 4. (Dec. 19, 1994), pp. 1047-1050.

 

Whiptails, due to their large populations and vast habitats, are good subjects when considering environmental stressors and impacts on various closely-related species. In the study at hand, the question being asked was of whether Western Whiptails in the northern area of their distribution had different clutch sizes in comparison to populations in more southerly areas. Great Basin Western Whiptails have been known to produce more than one clutch per reproductive season, but various populations tend to only produce one. This plasticity falls between two other  subspecies, C.t. gracilis and C.t. septentrionalis, of which the former produces several small clutches per year and the latter one large clutch per year. Phylogeny is still hazy in relation to the subspecies, thus the test was performed to see if relationships could be extricated.

 

     Methods: 174 C. t. tigris females were obtained from Utah, Colorado, Southwest Idaho, Arizona, and California, measured by snout-to-vent length, and dissected to find out the clutch sizes (both ovarian follicles and oviductal eggs were counted, but not corpora lutea). Only 86 were used, though, since the rest did not contain clutches.  Thus, 119 clutch samples of C.t. gracilis and 127 clutch samples of C.t. septentrionalis were obtained for comparison. Latitudes for the various specimens were located, as well as mean precipitation and elevation in the different areas.

 

        Table: Mean clutch size in C.t. gracilis, C.t. tigris, and C.t. septentrionalis with statistical parameters set for body size and elevation.

                  (Taylor, 1994)                 

 

     Results: While it is known that coloration and behaviors differ between populations of C.t. tigris, the statistical results of this study found little difference in the size of clutch, regardless of both latitude or body size. There were 10.8 degrees of latitudinal separation total, and the mean difference of snout-to-vent length was 2.5mm between C.t. tigris and C.t. gracilis, but this still did not produce a statistical difference after adjustment. Further studies will have to be done so as to determine why C.t. tigris may or may not produce multiple clutches.

 

References:

 

Cnemidophorus tigris - Baird and Girard, 1852 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 69
 
Digital Atlas of Idaho. 1997. http://imnh.isu.edu/digitalatlas/bio/reptile/lacer/cnti/cnti.htm Accessed Sept. 24, 2007.
 
NatureServe. 2007. NatureServe Explorer: An online encyclopedia of life [web application]. Version 6.2. NatureServe, Arlington, Virginia.
http://www.natureserve.org/explorer. Accessed September 24, 2007.
 
Reeder, T; Cole, C; and Dessaur, H. Phylogenetic Relationships of Whiptail Lizards of the Genus Cnemidophorus (Squamata: Teiidae): A Test of Monophyly, Reevaluation of Karyotypic Evolution, and Review of Hybrid OriginsAmerican Museum Novitates. Number 3365 (May 7, 2002), pp. 1-61.
 
The Reptile Database. 2007. J Craig Venter Institute. http://www.tigr.org/reptiles/ Accessed Sept. 24, 2007. 
 
Taylor, Harry; Harris, L; Burkholder, G; Walker, J. Relationship of Clutch Size to Body Size and Elevation of Habitat in Three Subspecies of the Teiid Lizard, Cnemidophorus tigris. Copeia, Vol. 1994, No. 4. (Dec. 19, 1994), pp. 1047-1050.
 
Taylor, Harry. Phenotypic and Reproductive responses of Aspidoscelis tigris (squamata: Teiidae) to shifts in Winter Precipitation Across the Southern Sierra NevadaRange, Kern County, California. The Southwestern Naturalist, Vol. 48, Issue 4 (Dec. 2003), pp. 680-684.
 
Urban, Emil K. Quantitative study of locomotion in teiid lizards. Animal Behavior. Vol. 13, Issue 4 (1965), pp. 513-529.
 
Western Ecological Research Center. March 5 2003. http://www.werc.usgs.gov/fieldguide/cnti.htm Accessed Sept 24, 2007 
 
World Wildlife Fund. WildFinder: Online database of species distributions, ver. Jan-06 www.worldwildlife.org/wildfinder Accessed Sept. 24, 2007. 
 

 

 

~ Page created by Sarah Dossey, sdossey@vandals.uidaho.edu

 

Comments (0)

You don't have permission to comment on this page.