Geographic Variation of Elaphe guttata (Reptilia: Serpentes) in the Atlantic Coastal Plain

Mitchell, Joseph C.

doi:10.2307/1443501

Cited by 10 publications

(11 citation statements)

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“…The significant latitudinal variation within populations limited to peninsular Florida suggests that geographic variation in scutellation may be even greater for the larger and more heterogeneous continental populations. Despite some regional divergences, ventral, subcaudal, and dorsal scale numbers generally increase from north to south for continental populations of Elaphe guttata (Mitchell, 1977;Thomas, 1974), Lampropeltis getula (Blaney, 1971), L. triangulum (Williams, 1978), and Thamnophis sirtalis (Fitch, 1941); only subcaudals show this pattern in T. proximus (Rossman, 1962) and T. sauritus (Rossman, 1963). Divergences from the general pattern in Lampropeltis triangulum may reflect the effects of elevation and habitat.…”

Section: Similar Differences Between Males and Females In Cs And Vs Amentioning

confidence: 99%

Geographic Variation in the Morphology of Crotalus Horridus (Serpentes: Viperidae)

Allsteadt

Savitzky

Petersen

et al. 2006

Herpetological Monographs

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The Timber Rattlesnake (Crotalus horridus) occurs in discontinuous populations throughout the eastern and central United States. The species exhibits high levels of polymorphism in morphological traits, especially in coloration and pattern. Previous studies recognized either distinct northern and southern subspecies or three regional morphs (northern, southern, and western), but conflicting data sets and limited geographic sampling o f previous studies have left the relationships among those regional variants unclear. In this study, univariate and multivariate statistics, together with a geographic information system, were used to analyze geographic variation in 36 morphological characters recorded from 2,420 specimens of C. horridus across its range.Sexual dimorphism was strong in ventral and subcaudal scales, and weak to moderate in band length and band spacing. Univariate analyses detected substantial geographic variation in all meristic characters. Scutellation exhibited a general northsouth pattern of variation, and most scale counts averaged higher in southern regions. Pattern characters differentiated the northeastern, central-eastern, and north-central regions from the southern and western regions. Coloration displayed a pattern of strong clinal variation among three broad areas consisting of the combined northeastern, centraleastern, and southern Appalachian regions, the northwestern regions, and the southern Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. regions. Morphometric characters exhibited a general north-south pattern of geographic variation, with larger head and body sizes in southern regions. Principal component analysis indicated that band length was the most important variable for characterizing geographic variation. The northeastern regions remained moderately distinct in all multivariate cluster analyses. The northwestern regions appeared very distinct in most cluster analyses for females. However, the clusters in all models showed extensive geographic overlap. Percentage maps of clusters revealed two north-south patterns of clinal variation among the northeastern, northwestern, and southern regions. The discordant patterns of variation among individual characters, the overlapping patterns of coloration, and the extensive overlap among the multivariate clusters collectively indicate that zones of intergradation among subpopulations of C.horridus are much broader than previously thought. Furthermore, the general patterns of geographic variation are strongly clinal and support the conclusion that C. horridus is a single widespread, polymorphic species.Reproduced with permission o f the copyright owner. Further reproduction prohibited without permission. V This dissertation is dedicated to my mother, Barbara Allsteadt, for her unconditional love and support.Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

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Section: Similar Differences Between Males and Females In Cs And Vs Amentioning

confidence: 99%

Geographic Variation in the Morphology of Crotalus Horridus (Serpentes: Viperidae)

Allsteadt

Savitzky

Petersen

et al. 2006

Herpetological Monographs

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“…Snakes are a suitable experimental ectothermic animal for examining the influence of coloration and body size on T b , because they exhibit a wide range of variation in these two physical properties, yet have a simple body form (Greene, 1997). Furthermore, the occurrence of intraspecific variation in both properties in some snakes ( e.g ., Mitchell, 1977;Rossman et al ., 1996;Tanaka and Ota, 2002) enables us to examine the relationship between coloration and body size and their effects on thermal properties without the confounding factor of phylogenetic constraints.…”

Section: Introductionmentioning

confidence: 99%

Thermal Aspects of Melanistic and Striped Morphs of the Snake Elaphe quadrivirgata

Tanaka

2005

Zoological Science

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Temperature is a critical factor limiting various aspects of the biology of ectotherms. In addition to environmental factors, coloration and body size are two physical properties that influence ectotherms' body temperature (T(b)). I compared the influences of these properties on thermal aspects of the two morphs of the color-dimorphic snake (E. quadrivirgata) under experimental conditions. First, I fitted T(b) data during heating to the von Bertalanffy equation, but considered parameter values of the equilibrium temperature obtained to be biologically meaningless. Alternatively, I limited the data for comparison of the morphs to T(b) < or =35 degrees C, which was the T(b) at which snakes began to move vigorously in the experiment. The rate of T(b) increase was significantly greater in the melanistic morph than in the striped morph. Heating rate was negatively correlated with body size in both morphs. The interaction of body size and heating rate did not significantly differ between the two morphs. The possibility of linkage, due to thermal advantage, between small body size and the prevalence of melanism in the population studied is briefly discussed. Rapid increase of T(b) is biologically advantageous because snakes with such ability would be released from various time and environmental constraints associated with thermoregulation under particular environmental conditions.

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“…comprimento rostro-cloacal (CRC), largura do corpo (LC) e largura do losângulo (LL) (MITCHELL, 1977;CASTELLANO et al, 1994) ou pode ser diretamente influenciada por parâmetros ambientais (FOX, 1948;FOX et al, 1961;THORPE, 1989a). Levando isso em consideração, a variação geográfica nos caracteres merísticos, pode ocorrer como resposta a diferentes parâmetros ambientais (THORPE et al, 1995), tais como a variação na latitude, elevação, temperatura, umidade, precipitação e sazonalidade (ALLSTEADT et al, 2006).…”

Section: Resultsunclassified

“…Em populações naturais do hemisfério Norte esta tendência é corroborada em varias espécies. Da mesma forma é detectada uma correlação entre as baixas temperaturas e o decréscimo no número de escamas segmentares em populações distribuídas ao Norte da amplitude de distribuição (PALMER, 1971), enquanto que as médias incrementam gradualmente até as áreas de ocorrência ao Sul (MITCHELL, 1977).…”

Section: Resultsunclassified

“…Em termos morfológicos, diferentes sistemas de caracteres, tais como os padrões de coloração, dados merísticos, morfologia interna, dentição e dimensões corporais são frequentemente avaliados, ao menos de uma perspectiva não-integrada, em estudos de variação geográfica de serpentes (FITCH 1940;MITCHELL, 1977;THORPE, 1989 a,b;CASTELLANO et al, 1994;KING, 1997), apresentando ao mesmo tempo implicações importantes dentro da taxonomia de cada grupo (ROZE, 1966;CAMPBELL;LAMAR, 2004).…”

Section: Introdução Geralunclassified

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A cascavel neotropical Crotalus durissus: uma abordagem morfológica e da historia natural em populações do Brasil

Argaez¹

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Geographic Variation of Elaphe guttata (Reptilia: Serpentes) in the Atlantic Coastal Plain

Cited by 10 publications

References 10 publications

Geographic Variation in the Morphology of Crotalus Horridus (Serpentes: Viperidae)

Geographic Variation in the Morphology of Crotalus Horridus (Serpentes: Viperidae)

Thermal Aspects of Melanistic and Striped Morphs of the Snake Elaphe quadrivirgata

A cascavel neotropical Crotalus durissus: uma abordagem morfológica e da historia natural em populações do Brasil

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