Ecology and Behavior of the Gila Monster in Southwestern Utah

Beck, Daniel

doi:10.2307/1564290

Cited by 53 publications

(54 citation statements)

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“…In fact, the Gila monster uses cloacal evaporative cooling to reduce body temperature when it becomes critically elevated (>37.5°C) (DeNardo et al, 2004). Gila monsters also conserve water by foraging infrequently (3-17% of the time during dry months) and selecting thermally and hydrically favorable refugia when inactive (Beck, 1990;Beck and Jennings, 2003) (J.R.D. and D.F.D., unpublished).…”

Section: Introductionmentioning

confidence: 99%

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

Davis

DeNardo

2007

Journal of Experimental Biology

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SUMMARY Animals inhabiting xeric environments use a variety of behavioral and physiological strategies to balance water budgets. We studied the potential contribution of the urinary bladder to osmoregulation in a large desert lizard, the Gila monster Heloderma suspectum. Here we present results of a series of in vivo laboratory experiments which tested the hypothesis that the Gila monster urinary bladder serves as a physiological reservoir, as in amphibians and chelonians, providing water that buffers increases in plasma osmolality when food and water are unavailable. Adult Gila monsters absorbed water from the urinary bladder into circulation and absorption of water from the urinary bladder and drinking water provided similar osmoregulatory benefits within 24 h, although drinking water provided a more immediate osmotic benefit. During food and water deprivation, plasma osmolality increased 2.5 times faster in lizards with an empty urinary bladder compared with those with a full bladder. During rehydration, stereotyped binge drinking behavior increased body mass nearly 22%, which resulted in a 24%reduction in plasma osmolality and a substantial increase in bladder water within 24 h. These results support our hypothesis and demonstrate for the first time in an adult lizard that the urinary bladder can function as a long-term physiological water reservoir. This trait can provide a critical benefit to osmoregulation during the 2- to 3-month summer dry season characteristic of the deserts that Gila monsters inhabit.

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Section: Introductionmentioning

confidence: 99%

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

Davis

DeNardo

2007

Journal of Experimental Biology

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“…For instance, during much of the active season Gila monster surface activity is low, predominantly entails foraging for widely dispersed resources (Beck, 1990(Beck, , 2005, and occurs mostly at night (at our Sonoran Desert field site) when the lack of solar irradiation results in Gila monster T b 's that closely mimic T air (Fig. 2b).…”

Section: Discussionmentioning

confidence: 98%

“…Our estimate that Gila monsters spend 17% of the active season surface active exceeds other published estimates for Gila monsters based solely on radiotelemetry and field observations. In Arizona, activity estimates range from 2% to 5% (Lowe et al, 1986) and extensive work by Beck (1990Beck ( , 2005 suggests o5% annual surface activity for Gila monsters in Utah and New Mexico. These differences may be explained by differences in methodology (semi-continuous vs. point-sampling, 24 h vs. diurnal sampling) or environmental conditions (e.g., the occurrence of late summer monsoon rainfall).…”

Section: Discussionmentioning

confidence: 99%

“…We recorded T b semi-continuously from a group of western diamondbacked rattlesnakes (Crotalus atrox Baird and Girard) and a sympatric group of Gila monsters (Heloderma suspectum Cope) at the field site. These species are well suited for this study because they are long-lived, large enough (adult mass ¼ 300-700 g) to accommodate radiotransmitters and temperature loggers, and easily located using radiotelemetry (Beck, 1990;. Moreover, neither species typically use active behavioral thermoregulation outside of specific periods (i.e., both bask upon emergence from overwinter dormancy) and both are known to spend substantial time in a variety of refugia and shift predominantly to nocturnal surface activity during hot summer months, which simplifies TBAE by eliminating solar irradiation as a heat source (Beck and Jennings, 2003;J.…”

Section: Study Speciesmentioning

confidence: 99%

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An automated temperature-based option for estimating surface activity and refuge use patterns in free-ranging animals

Davis

Taylor

DeNardo

2008

Journal of Arid Environments

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Accurately assessing free ranging animals' patterns of surface activity and refuge use is critical, yet fundamentally challenging for biologists and wildlife managers. We evaluate the accuracy of an automated technique temperature based activity estimation (TBAE) in estimating surface activity and refuge use patterns of two sympatric reptiles, the western diamond backed rattlesnake (Crotalus atrox) and the Gila monster (Heloderma suspectum) in the Sonoran Desert. TBAE derived from a comparison of body temperature to shaded air temperature was effective in estimating the overall percent surface activity for both rattlesnakes (observed surface activity 51.8%, TBAE estimated surface activity 48.2%) and Gila monsters (observed 22.3%, TBAE 24.5%). There was, however, considerable interspecific difference in the effectiveness of TBAE in predicting surface activity at specific time points; TBAE was far more accurate for Gila monsters than for rattlesnakes (96% vs. 66% time point specific accuracy, respectively). We assert that, when validated, TBAE can be used to yield concurrent and accurate body temperatures and activity estimates for multiple free ranging animals, particularly in arid environments, which improves our understanding of animal biology and can be used to inform management decisions.

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“…The precise role of venom in the ecology of helodermatid lizards remains unknown. Beck (Beck, 1990) considered it a "paradox" that helodermatid lizards hold on "with bulldog tenacity" when biting in apparent defence, thus increasing the lizard's chance of injury or death. But this assertion merely reflects a common fallacy of evolutionary thinking -that the individual lizard is the "unit of selection".…”

Section: Figure 1: Reduced and Non-reduced Tris-tricine 1d-gel Comparmentioning

confidence: 99%

An investigation of the evolution of the anguimorph lizard venom system

Koludarov¹

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Over the course of the last two decades significant advances were made in our understanding of the evolution of venom in squamate reptiles. Several studies looked at nuclear genes from various lizards and snakes and confirmed the hypothesis put forth in E. Kochva's article "Phylogeny of the oral glands in reptiles as related to the origin and evolution of snakes" -that anguimorph lizards form part of a monophyletic clade with all the snakes. This confirmation confounded decades of morphology based taxonomy, as did evidence of the inclusion of the Iguania lizard lineage into that group. The new group received the name Toxicofera, emphasizing the role of oral toxins in the evolution of the lineage. Despite being supported by genetic, anatomical and proteomic data, the Toxicofera hypothesis remains controversial. This strengthens the necessity for thorough investigation of toxicoferan reptile venom evolution. The oral secretions of anguimorph lizards demand particular attention not only because they are understudied, but also for the reason that Anguimorpha contains species with the considerable morphological diversity of venom glands -from incipient to advanced and almost snake-like.Therefore the primary goal of this thesis is to address the lack of knowledge on anguimorph lizard oral secretions, in particular that of varanoid lizards which include various monitor species (genus Varanus) as well as Heloderma (gila monster) and Lanthanotus (Borneo earless monitor). This has been achieved through the implementation of several proteomic techniques (in particular, gel electrophoresis) as well as transcriptomic analysis and bioactivity testings.Chapter One reviews all previously published information on anguimorph venom evolution, highlighting the data in support of the Toxicofera hypothesis. Chapter Two presents new data on Heloderma lizard venoms and the striking similarities between the venom profiles of specimens from different localities as well as between species. The data presented and discussed in Chapter Three represents the core finding of this study: the surprising complexity and diversity of varanid lizard oral secretions.Taken together, this study present a compelling argument in favour of functional diversity and differential complexity of the venom of anguimorph lizards and discusses the evolutionary forces that helped generate this diversity.

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Ecology and Behavior of the Gila Monster in Southwestern Utah

Cited by 53 publications

References 13 publications

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monsterHeloderma suspectum

An automated temperature-based option for estimating surface activity and refuge use patterns in free-ranging animals

An investigation of the evolution of the anguimorph lizard venom system

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