Sceloporus Undulatus: A Study of the Intraspecific Comparative Demography of a Lizard

Abstract

Population studies were conducted on the eastern fence lizard in South Carolina, Texas, Ohio, and Colorado. Hatching occurs in early to middle summer and well into the fall in southern populations, but is restricted to late summer and early fall in Colorado and Ohio. The hatchlings in Texas reach a mature size in 3 months and these lizards, as well as those in South Carolina, reproduce before they are a year old. In Colorado and Ohio the lizards do not mature until almost 2 years of age, but at a larger size than those in Texas or South Carolina. Lizards in the four populations differ significantly in average clutch size (7.4-11.8) and in clutch frequency (1-3) and in egg size (.23-.42 g per egg). In all populations there is a significant positive correlation between clutch size and body size and the regression lines for these variables differ in slope between populations. Survivorships of eggs, hatchlings, yearlings, and adults differ among the populations and these differences have been related indirectly to increased predation in the southern and western populations. The adult mortality rates are inversely related to population density. Life tables for the populations show large differences among the populations in the contribution made by each age class to the total population replacement rate. The life table characteristics of each population show that the measured parameters are consistent with maintenance of stable population numbers even though the life history strategies are clearly different. Evolutionary explanations are provided for these differences and the relevance of the data to the concept of r-and K-selection is discussed.

Quantitative Predictions of Delayed Maturity

“…The Quality of Young Model (QYM).-We make the same assumptions that we used to build the Salamander Model, but we also specify that fecundity is a constant for all ages at maturity, We used published data on salamanders (Tilley, 1979) and lizards (Blair, 1960;Tinkle, 1967;Tinkle and Ballinger, 1972;Vinegar, 1976) for the estimates of the constants. There are serious problems with inferring these parameters from the available data, for they require that one know what fecundity or mortality would have been if the organism had matured at a different age.…”

Phylogenetic Comparative Analysis of Life-History Variation Among Populations of the Lizard Sceloporus Undulatus:an Example and Prognosis

“…Life histories have been documented in many disjunct populations throughout its range, and some life-history phenotypes vary more than twofold among populations (reviewed by Tinkle and Ballinger 1972;Tinkle and Dunham 1986;Gillis and Ballinger 1992;Niewiarowski 1994). Comparative, experimental, and theoretical studies have suggested many hypotheses (adaptive and nonadaptive) to account for this geographic variation in life histories (Stearns and Crandall 1981;Grant and Porter 1992;Adolph andPorter 1993, 1996;Niewiarowski 1994Niewiarowski , 2001Angilletta 2001).…”

Selected bibliography of Wyoming amphibians and reptiles

“…1977;Baxter andStone 1980. Habitat utilization: Tanner 1965;Ferguson 1971;Tinkle 1972;Tinkle and Ballinger 1972;Werth 1972;Ferner 1974Ferner , 1976Turner 1974;Baxter and Stone 1980;Jones and Droge 1980;Waldschmidt 1980;Hammerson andLanglois 1981. Feeding: Woodbury 1932;Johnson 1966;Werth 1972;Turner 1974;Ferner 1976;Baxter andStone 1980.…”

“…Feeding: Woodbury 1932;Johnson 1966;Werth 1972;Turner 1974;Ferner 1976;Baxter andStone 1980. Breeding: Ferguson 1971;Tinkle 1972;Tinkle and Ballinger 1972;Turner 1974;Derickson 1976;Ferner 1976;Baxter and Stone 1980;Ferguson et al . 1980;Ballinger et al 1981.…”