Rulon W Clark

Rulon W Clark
San Diego State University | SDSU · Department of Biology

PhD

About

104
Publications
50,129
Reads
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1,631
Citations
Additional affiliations
January 2011 - December 2012
San Diego State University
August 2007 - December 2020
San Diego State University
Position
  • Professor (Full)
January 2004 - December 2012
Cornell University

Publications

Publications (104)
Article
The warming of the Arctic is affecting the carbon cycle of tundra ecosystems. Most research on carbon fluxes from Arctic tundra ecosystems has focused on abiotic environmental controls (e.g., temperature, rainfall, or radiation). However, Arctic tundra vegetation, and therefore the carbon balance of these ecosystems, can be substantially impacted b...
Article
Full-text available
Body temperature influences the activity and behavior of reptiles, with warmer body temperatures typically being associated with improved performance. Nocturnal ambush-hunting rattlesnakes would therefore benefit from selecting warmer substrate hunting sites, allowing them to stay in ambush longer as the environment cools and, presumably, to have a...
Article
Full-text available
Predators that feed on dangerous prey species must evolve mechanisms to reduce the likelihood of injury or death during a predation attempt. Scorpions are prime examples of dangerous prey items for insectivores, because they can inflict a venomous and potentially fatal sting when attacked. Despite this risk, the western banded gecko (Coleonyx varie...
Preprint
Full-text available
The Arctic is warming at double the average global rate, affecting the carbon cycle of tundra ecosystems. Most research on carbon fluxes from Arctic tundra ecosystems has focused on abiotic environmental controls (e.g. temperature, rainfall, or radiation). However, Arctic tundra vegetation, and therefore the carbon balance of these ecosystems, can...
Article
Most viperids are ambush predators that primarily use venom to subdue prey, employing a strike-release-trail hunting strategy whereby snakes follow the unique scent of envenomated prey to locate carcasses they have bitten and released. In addition to killing prey, rattlesnakes (like most carnivores) will also opportunistically scavenge carrion. Thi...
Article
Full-text available
Body size is a key factor that influences antipredator behavior. For animals that rely on jumping to escape from predators, there is a theoretical trade-off between jump distance and acceleration as body size changes at both the inter- and intraspecific levels. Assuming geometric similarity, acceleration will decrease with increasing body size due...
Article
Full-text available
Predator-prey interactions often lead to the coevolution of adaptations associated with avoiding predation and, for predators, overcoming those defenses. Antagonistic coevolutionary relationships are often not simple interactions between a single predator and prey but rather a complex web of interactions between multiple coexisting species. Coevolu...
Article
Full-text available
Chemosensory searching in squamates with specialized tongue–vomeronasal systems is well-documented. By tongue-flicking, these reptiles gather important chemical cues from their environment to guide their feeding behavior. Strike-induced chemosensory searching (SICS) is a specific expression of chemosensory reception that is central to the predatory...
Article
Full-text available
Synopsis Tails are widespread in the animal world and play important roles in locomotor tasks, such as propulsion, maneuvering, stability, and manipulation of objects. Kangaroo rats, bipedal hopping rodents, use their tail for balancing during hopping, but the role of their tail during the vertical evasive escape jumps they perform when attacked by...
Article
Ecologists have long theorized that apex predators stabilize trophic systems by exerting a net protective effect on the basal resource of a food web. Although experimental and observational studies have borne this out, it is not always clear what behavioural mechanisms among the trophically connected species are responsible for this stability. Fear...
Article
Full-text available
Most animals have predators, and therefore must balance the needs of foraging and mating with those of shelter and safety. Many species rely on chemosensory cues to identify predators and organize defenses specific to particular types of predators. A large body of research in this area has focused on lizards and snakes because they have heightened...
Article
Full-text available
Sexual selection studies often focus on morphological traits that are important only in the later stages of mate acquisition. Comparatively little is known about traits that lead to mate acquisition, such as mate-searching activities. We experimentally manipulated body condition (i.e., the energy reserves) in male puff adders (Bitis arietans) prior...
Article
Full-text available
The authors would like to correct the error in table 4 which was incorrectly published in original version. Correct version of Table 4 is updated here.
Research
Correction to article: Male energy reserves, mate‑searching activities, and reproductive success: alternative resource use strategies in a presumed capital breeder
Article
Full-text available
Decades of research on sexual selection have demonstrated that 'conventional' Darwinian sex roles are common in species with anisogamous gametes, with those species often exhibiting male-biased sexual selection. Yet, mating system characteristics such as long-term sperm storage and polyandry have the capacity to disrupt this pattern. Here, these id...
Article
Full-text available
Using venom for predation often leads to the evolution of resistance in prey. Understanding individual variation in venom resistance is key to unlocking basic mechanisms by which antagonistic coevolution can sustain variation in traits under selection. For prey, the opposing challenges of predator avoidance and resource acquisition often lead to co...
Article
Full-text available
The outcomes of predator-prey interactions between endotherms and ectotherms can be heavily influenced by environmental temperature, owing to the difference in how body temperature affects locomotor performance. However, as elastic energy storage mechanisms can allow ectotherms to maintain high levels of performance at cooler body temperatures, det...
Article
Full-text available
Long‐term ecological monitoring provides valuable and objective scientific information to inform management and decision‐making. In this article, we analyze 22 years of herpetofauna monitoring data from the Point Loma Ecological Conservation Area (PLECA), an insular urban reserve near San Diego, CA. Our analysis showed that counts of individuals fo...
Article
Full-text available
Movements of ectotherms are constrained by their body temperature due to the effects of temperature on muscle physiology. As physical performance often affects the outcome of predator-prey interactions, environmental temperature can influence the ability of ectotherms to capture prey and/or defend themselves against predators. However, previous res...
Article
Body size is a key selected trait in many animal systems: larger size is sexually selected for in males because it confers a reproductive advantage during contest competition for access to females, and larger females are naturally selected for fecundity. Herein, we used radio‐telemetry to gather a large dataset of male–female interactions and DNA p...
Article
Toxic or noxious prey often signal their unpalatability through aposematic coloration, and the evolution of aposematism has become a model system in evolutionary behaviour. Aposematic colours are not only easily recognized by predators, but, for many predators, aposematism enhances learning and memory retention. In this study, we used a visually or...
Conference Paper
Full-text available
Sexual selection theory predicts that the sex in greater abundance and with "cheaper" gametes will experience increased reproductive success as a result of an increased number of matings, whereas the sex with more finite numbers of gametes and in lesser abundance will experience no such gain. Empirical data across taxa have supported the prevalence...
Article
Full-text available
Upon sensing predators in their vicinity, many prey species perform antipredator displays that are thought to provide information to the predator that deters it from attacking (predator‐deterrent signals). These displays can be complex, incorporating a variety of signaling elements as well as direct physical harassment of the predator. Although the...
Article
Full-text available
1. The selection pressures that arise from capturing prey and avoiding predators are some of the strongest biotic forces shaping animal form and function. Examining how performance (i.e., athletic ability) affects the outcomes of encounters be- tween free-ranging predators and prey is essential for understanding the determinants of predation succes...
Article
Full-text available
Many animals exhibit morphological specializations driven by the extreme selective pressure of predation, and understanding how such specializations shape escape behaviours can elucidate the evolutionary context of these morphologies. We examined the kinematics of the evasive leaps of desert kangaroo rats (Dipodomys deserti) during strikes from sid...
Article
Full-text available
Sensory information drives the ecology and behaviour of animals, and some animals are able to detect environmental cues unavailable to us. For example, rattlesnakes use infrared (IR) radiation to detect warm prey at night when visual cues are reduced. Until recently these sensory worlds have been inaccessible to human observers; now technology can...
Article
Full-text available
Many animals exhibit morphological specializations driven by the extreme selective pressure of predation, and understanding how such specializations shape escape behaviours can elucidate the evolutionary context of these morphologies. We examined the kinematics of the evasive leaps of desert kangaroo rats (Dipodomys deserti) during strikes from sid...
Article
Full-text available
Animal movements govern most ecological interactions, from predation to reproduction and survival. How animals move through the environment depends on available sensory information. Some snakes are able to perceive infrared (IR) radiation in addition to visible light. Research on this sensory system has been almost exclusively focused on predation,...
Article
Full-text available
Population genetic patterns can be affected by a number of factors, including life history characteristics and landscape features. Identifying general patterns of connectivity and key factors affecting these patterns is often central to effective ecological monitoring and management, particularly in areas with increasing urbanization. Examining pat...
Article
Full-text available
The pit organ defining pit vipers (Crotalinae) contains a membrane covered with temperature receptors that detect thermal radiation from environmental surfaces. Temperature is both the environmental parameter being sensed and the mechanism by which the pit membrane detects the signal. As snakes are ectotherms, temperature also has a strong influenc...
Article
Full-text available
Rattlesnakes use infrared radiation to detect prey animals such as small mammals and lizards. Because ectotherm locomotor performance depends on temperature, rattlesnakes could use prey temperature to evaluate the potential of lizards to evade attacks. Here, we tested whether hunting rattlesnakes use infrared information to (1) detect and (2) evalu...
Preprint
Full-text available
Habitat loss and fragmentation is one of the most severe threats to global biodiversity. Because human development often fragments natural areas into habitat “islands”, studies which characterize the genetic structure of species isolated on oceanic islands may provide insight into the management of anthropogenic habitat islands. The San Clemente Is...
Article
Full-text available
When predators rely on high-speed movements to capture prey, prey often exhibit traits that result in correspondingly extreme physical performance. Biomechanical studies of these interactions are typically conducted in laboratory settings, thereby eliminating some of the ecological context. We studied how behavioural state, specifically vigilance l...
Article
Full-text available
A diverse range of prey taxa exhibit stereotyped antipredator behaviors when confronting live predators. Predator cues also elicit antipredator responses, and previous research indicates that prey possess mechanisms to discriminate between the relative risk posed by particular predator cues, which mediates their investment in antipredator behaviors...
Article
Full-text available
Prey often use conspicuous or aposematic coloration to advertise their unprofitability to potential predators. Although most research focuses on coloration, other characteristics, such as the shape or size of markings, or general body shape and appearance, can be used by predators to recognize unprofitable prey. These more general characters may be...
Preprint
Full-text available
The extinction risk of insular species with sessile life histories is expected to increase as they may be unable to track habitat in response to global climate change. Demogenetic simulations can couple population demography and niche modeling to produce spatially-explicit genetic and demographic information for all simulated individuals and provid...
Article
Full-text available
Many species perform complex antipredator displays that deter attacks by informing predators that continued attempts at prey capture will be costly. However, because of the difficulties in studying the behaviour of free-ranging predators, we have a limited understanding of how predators respond to those signals. Here, we took advantage of our abili...
Preprint
Full-text available
Characterizing dispersal and movement patterns are vital to understanding the evolutionary ecology of species. For many reclusive species, such as reptiles, the observation of direct dispersal may be difficult or intractable. However, dispersal distances and patterns may be characterized through indirect genetic methods. We used genetic and capture...
Article
Predator presence causes acute stress in mammals. A prey animal's stress response increases its chance of survival during life-threatening situations through adaptive changes in behavior and physiology. Some components of the physiological stress response can lead to changes in body surface temperatures. Body temperature changes in prey could provi...
Article
Increasing temperature due to climate change is one of the greatest challenges for wildlife worldwide. Behavioral data on free-ranging individuals is necessary to determine at what temperatures animals modify activity as this would determine their capacity to continue to move, forage, and mate under altered thermal regimes. In particular, high temp...
Article
Full-text available
Predation plays a central role in the lives of most organisms. Predators must find and subdue prey to survive and reproduce, whereas prey must avoid predators to do the same. The resultant antagonistic coevolution often leads to extreme adaptations in both parties. Few examples capture the imagination like a rapid strike from a venomous snake. Howe...
Chapter
Full-text available
Breaking conceptual barriers that concern the complexity and importance of social behavior in snakes has been a lingering and uneasy progression for ethologists, herpetologists, and other scientists who study their biology. Certainly, in popular western culture, these biases remain largely unchanged (Burghardt et al., 2009; Doody et al., 2013), but...
Article
Full-text available
Squamate reptiles have highly developed chemosensory systems used to detect both predators and prey. Although the general ability of squamates to assess predation risk using chemical cues is well known, the detail to which squamates can make discriminations concerning risk is largely unexamined. Granite Night Lizards (Xantusia henshawi) are habitat...
Article
Full-text available
Several lineages of small mammals frequently preyed upon by snakes have evolved snake-specific signals and displays that they use in an attempt to deter predation. Although detailed studies have been conducted on the form and function of these behaviors in a few key species, limited work has been done that directly compares behaviors between specie...
Article
Full-text available
Foraging is a key aspect of a species’ ecology and decisions made while foraging affect fitness in many ways. Although much research has focused on snake foraging, only a handful of detailed studies have been conducted on free-ranging individuals, all on Crotalus horridus. We used fixed videography to collect data on free-ranging Northern Pacific R...