Comparative thermal ecology of the high-altitude lizard Sceloporus grammicus on the eastern slope of the Iztaccihuatl Volcano, Puebla, Mexico

1995 ◽  
Vol 73 (12) ◽  
pp. 2184-2191 ◽  
Author(s):  
Julio A. Lemos-Espinal ◽  
Royce E. Ballinger
Keyword(s):  
High Altitude ◽  
Thermal Environment ◽  
High Elevation ◽  
Thermal Ecology ◽  
Body Temperatures ◽  
Thermoregulatory Behavior ◽  
Thermal Environments ◽  
Sceloporus Grammicus ◽  
Study Sites ◽  
Similar Body

We studied the thermal ecology of Sceloporus grammicus occurring in very different thermal environments at 3700 and 4400 m elevation on the Iztaccihuatl Volcano, Mexico. Despite differences in the thermal environment between study sites, individual lizards maintained similar active body temperatures (around 31.5 °C). Similar body temperatures at the two study sites probably result in differences in the cost of the thermoregulatory behavior. Lizards at the high-altitude site, an open area with few predators or competitors, presumably incur a lower thermoregulatory cost than those at the low-altitude site, which has a considerable number of shaded spots and more predators and competitors. Lizards at the low-elevation site showed a greater resistance to high temperatures than those at the high-elevation site. Physiological acclimatization to higher environmental temperatures at low elevation is likely to explain the greater heat tolerance. Freezing tolerance, thermoregulatory behavior, and low energy requirements permit S. grammicus to survive at high altitudes.

High-mountain altitudinal gradient influences thermal ecology of the Mesquite Lizard (Sceloporus grammicus)

2019 ◽  
Vol 97 (8) ◽  
pp. 659-668 ◽  
Author(s):  
A.H. Díaz de la Vega-Pérez ◽  
R. Barrios-Montiel ◽  
V.H. Jiménez-Arcos ◽  
A. Bautista ◽  
E. Bastiaans
Keyword(s):  
Altitudinal Gradient ◽  
The Body ◽  
High Mountain ◽  
Thermal Ecology ◽  
Behavioral Strategies ◽  
Body Temperatures ◽  
Altitudinal Distribution ◽  
Thermal Requirements ◽  
Sceloporus Grammicus

The thermal requirements of ectotherms may vary among species due to adaptation to different thermal environments. Nevertheless, some of these requirements are evolutionarily conserved, leading organisms to compensate behaviorally for harsh environmental conditions. High-mountain systems provide temperature gradients that allow for studies of evolutionary and plastic variation in thermal ecology under natural conditions. We evaluated the thermoregulation strategies of Sceloporus grammicus Wiegmann, 1828 at three points (2600, 3100, and 4150 m above sea level) along an altitudinal gradient. We found that the thermal quality of the site and the body temperatures of lizards are influenced by altitude and decrease with increasing elevation. However, lizards from the three different elevations have similar thermal requirements. High-altitude lizards have lower thermal accuracy and efficiency indices compared with those from the lower sites, owing to the low thermal quality of their environment. Nevertheless, they are efficient in thermoregulation, increasing their body temperature above the ambient temperature. We found that pregnant females from all three elevations had similar preferred body temperatures. Compared with nonpregnant females and males, they exhibited lower preferred temperatures and more accurate thermoregulation. The wide altitudinal distribution of S. grammicus is thus not caused by variable thermal requirements. Instead, the wide repertoire of physiological and behavioral strategies of these lizards allows this species to successfully inhabit contrasting environments.

Field Body Temperatures and Thermoregulatory Behavior of the High Altitude Lizard, Lacerta bedriagae

1990 ◽  
Vol 24 (1) ◽  
pp. 88 ◽  
Author(s):  
Dirk Bauwens ◽  
Aurora M. Castilla ◽  
Raoul Van Damme ◽  
Rudolf F. Verheyen
Keyword(s):  
High Altitude ◽  
Body Temperatures ◽  
Thermoregulatory Behavior

scholarly journals To be small and dark is advantageous for gaining heat in mezquite lizards, Sceloporus grammicus (Squamata: Phrynosomatidae)

2020 ◽  
Vol 132 (1) ◽  
pp. 93-103
Author(s):  
Juan Carlos González-Morales ◽  
Jimena Rivera-Rea ◽  
Gregorio Moreno-Rueda ◽  
Elizabeth Bastiaans ◽  
Héctor Díaz-Albiter ◽  
...  
Keyword(s):  
Body Size ◽  
High Altitude ◽  
Heating Rate ◽  
Small Body ◽  
Individual Performance ◽  
Lizard Species ◽  
Heat Gain ◽  
Thermal Environments ◽  
Sceloporus Grammicus ◽  
Thermal Melanism

Abstract Body temperature is important in determining individual performance in ectotherms such as lizards. Environmental temperature decreases with increasing altitude, but nevertheless many lizards inhabit high-altitude environments. The ‘thermal melanism hypothesis’ proposes that a dark dorsal coloration enables darker individuals to heat up faster because they absorb more solar radiation and thus being darker may be advantageous in cold habitats. The aim of the present study is to evaluate how heating rate, cooling rate and net heat gain vary with body size and dorsal skin coloration in Sceloporus grammicus lizards along an altitudinal gradient. We measured these traits multiple times in the same individuals with a radiation heat source and spectrophotometry under laboratory conditions. Our results showed that S. grammicus lizards are smaller and darker at high elevations than at low elevations. In addition, the smallest and darkest lizards showed the greatest heating rate and net heat gain. Therefore, in S. grammicus, we suggest that small body size and dark dorsal coloration provide thermoregulatory benefits in high-altitude environments. Hence, this study supports the thermal melanism hypothesis in a lizard species under varied thermal environments.

Thermal biology of the spotted snow skink, Niveoscincus ocellatus, along an altitudinal gradient

2018 ◽  
Vol 66 (4) ◽  
pp. 235 ◽  
Author(s):  
Luh P. E. K. Yuni ◽  
Susan M. Jones ◽  
Erik Wapstra
Keyword(s):  
Body Temperature ◽  
High Altitude ◽  
Altitudinal Gradient ◽  
Thermal Environment ◽  
The Body ◽  
Activity Period ◽  
Lower Body ◽  
Body Temperatures ◽  
Mean Body Temperature ◽  
Thermal Biology

Body temperatures in ectotherms are strongly affected by their thermal environment. Ectotherms respond to variation in the thermal environment either by modification of behavioural thermoregulation to maintain their optimal body temperature or by shifting their optimal body temperature. In this study, the body temperatures of males of three populations of spotted snow skinks, Niveoscincus ocellatus, living along an altitudinal gradient (low, mid, and high altitude) were studied in the field and laboratory in spring, summer, and autumn, representing the full activity period of this species. The environmental variation across both sites and seasons affected their field active body temperatures. At the low and mid altitude, N. ocellatus had a higher mean body temperature than at the high altitude. Animals achieved their thermal preference at the low and mid altitude sites in all seasons. At the high altitude, however, N. ocellatus struggled to reach its preferred body temperatures, especially in autumn. The lower body temperature at the high-altitude site is likely due to limited thermal opportunity and/or an effect of avoiding the costs associated with increased intensity of basking.

Thermal ecology of the high-altitude bunch grass lizard, Sceloporus scalaris

1993 ◽  
Vol 71 (11) ◽  
pp. 2152-2155 ◽  
Author(s):  
Geoffrey R. Smith ◽  
Royce E. Ballinger ◽  
Justin D. Congdon
Keyword(s):  
Body Temperature ◽  
High Altitude ◽  
Air Temperature ◽  
Early Summer ◽  
The Body ◽  
Thermal Ecology ◽  
Body Temperatures ◽  
Vegetative Cover ◽  
Mean Body Temperature ◽  
Early Maturity

The thermal ecology of a high-altitude lizard, Sceloporus scalaris, was investigated in the Chiricahua Mountains of southeastern Arizona, where the lizards are active on sunny days throughout the year. Mean body temperature was 32.6 °C (range 12.6–39 °C) and mean air temperature was 20.2 °C (range 5.2–36.4 °C). The slope of the body temperature versus air temperature regression was 0.23. Monthly differences in body temperature were observed, with the highest body temperatures observed in early summer. Lizards at three study sites with differing slope and vegetative cover had different mean body temperatures. Males had higher body temperatures than both nongravid and gravid females. Maintenance of elevated body temperatures even during winter lengthens the activity and growing season, permitting early maturity with potentially important life-history consequences.

Warm-Up Rates and Body Temperatures in Bees: The Importance of Body Size, Thermal Regime and Phylogeny

1989 ◽  
Vol 147 (1) ◽  
pp. 303-328 ◽  
Author(s):  
G. N. Stone ◽  
P. G. Willmer
Keyword(s):  
Body Mass ◽  
Thermal Environment ◽  
Regression Method ◽  
Lower Body ◽  
Body Temperatures ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Thermal Environments ◽  
Phylogenetic Regression ◽  
The Relationship

1. We assess the importance of body mass and the minimum ambient temperature at which foraging occurs in determining the warm-up rates and thoracic temperatures in flight at an air temperature of 22°C of 55 species of bee (Hymenoptera: Apoidea) from six families adapted to a variety of thermal environments. 2. To control for the effects of taxonomic differences in the relationships between these variables, we use multiple regression incorporated in the phylogenetic regression method developed by Grafen (1989). 3. The prediction made by May (1976) that for very small heterotherms warmup rate will correlate positively with body mass is confirmed when the effects of phylogeny and the thermal environment to which the bee is adapted have been controlled for. The relationship between warm-up rate and body mass within the Apoidea is thus not an extension to lower body masses of the relationship found for heterothermic vertebrates. 4. Having controlled for the effects of body mass in our analyses, we demonstrate that bees able to fly at lower ambient temperatures have higher thoracic temperatures and warm-up rates than bees adapted to wanner environments. 5. There is some suggestion that kleptoparasitic bees, being freed from the need to forage in order to provision cells, have lower warm-up rates than provisioning species. 6. The significance of these relationships in the ecology of bees is discussed in relation to studies of body temperatures and warm-up rates in bees and other insects.

Habitat selection in two sympatric Chinese skinks, Eumeces elegans and Sphenomorphus indicus: do thermal preferences matter?

2006 ◽  
Vol 84 (9) ◽  
pp. 1300-1306 ◽  
Author(s):  
W.G. Du ◽  
L. Shou ◽  
J.Y. Shen
Keyword(s):  
Habitat Selection ◽  
Thermal Environment ◽  
Activity Patterns ◽  
Cold Climate ◽  
Habitat Partitioning ◽  
Body Temperatures ◽  
Thermal Physiology ◽  
Thermal Requirements ◽  
Thermal Environments ◽  
Thermal Preferences

We studied the habitat selection and thermal biology of two sympatric Chinese skinks ( Eumeces elegans Boulenger, 1887 and Sphenomorphus indicus (Schmidt, 1928)) to test the effect of thermal preference on habitat partitioning. We measured thermal and structural attributes of the microhabitats occupied by these two skink species, as well as their field body temperatures and activity patterns. We then quantified the preferred body temperatures of these species in a thermal gradient. Compared with S. indicus, E. elegans occupied microhabitats with fewer trees, more rocks, and higher ambient temperatures. Active S. indicus were mainly found in the morning, whereas active E. elegans were found at noon. The thermal environment of the microhabitats at these two periods correlated with the skinks’ thermal preferences. Preferred temperatures of E. elegans were significantly higher than those of S. indicus. These results support (i) the hypothesis that habitat partitioning between ectotherms is related to interspecific differences in thermal requirements; (ii) the labile hypothesis that describes the adaptability of thermal physiology, because the two sympatric skinks, which select different thermal environments, differed in thermal physiology; and (iii) the cold-climate hypothesis that explains the evolution of viviparity, because viviparous S. indicus occupy colder habitats than do oviparous E. elegans.

The ecology of an Australian reptile icon: how do blue-tongued lizards (Tiliqua scincoides) survive in suburbia?

2001 ◽  
Vol 28 (3) ◽  
pp. 214 ◽  
Author(s):  
Jennifer Koenig ◽  
Richard Shine ◽  
Glenn Shea
Keyword(s):  
Ecological Factors ◽  
Home Ranges ◽  
Minimal Risk ◽  
Body Temperatures ◽  
Avoided Crossing ◽  
In Captivity ◽  
Radio Transmitters ◽  
Core Areas ◽  
Study Sites ◽  
Gravid Females

Although most species of large reptiles in the Sydney region are now restricted to remnant bushland, the blue-tongued lizard (Tiliqua scincoides) remains abundant. How has this large, slow-moving reptile managed to persist in the suburbs? We implanted radio-transmitters into 17 adult blue-tongued lizards and tracked them for six months (October 1998 to March 1999). Radio-tracked animals utilised 5–17 suburban backyards, but each lizard spent most of its time in a few ‘core’ areas near 2–7 shelter sites. Males had larger home ranges than females (mean of 12700 v. 5100 m 2 ) and moved further between shelter sites. Gravid females (mean home range 1000 m 2 ) were more sedentary. Lizards used corridors of dense vegetation to move between retreat sites, and actively avoided crossing roads. In sunny weather, lizards typically basked close to their overnight shelter for 1–4 h each morning until they obtained body temperatures of approximately 32°C. They maintained high body temperatures while moving about in the afternoon. In combination, the following ecological factors may facilitate persistence of blue-tongued lizards at our suburban study sites. (i) The most important subgroup of the population in terms of conservation are gravid females, which are highly sedentary and, thus, less likely to encounter the dangers of suburbia. (ii) The more ‘expendable’ males move about much more, but mostly in times and places that involve minimal risk from humans and their domestic pets. (iii) Lizards show strong site fidelity, spending up to 70% of their time in ‘safe’ locations; importantly, they avoid roads. (iv) Blue-tongued lizards readily utilise ‘artificial’ shelter sites and the commensal prey species (e.g. snails) found in most gardens. (v) These lizards can grow rapidly, mature early, and produce large litters. Because blue-tongued lizards have a long life span (over 30 years in captivity), populations of adults may persist for many years in the absence of recruitment.

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