Sympatric Lizard Species Research Articles

Impact of blood parasites on the behaviour of two congeneric wall lizards (genus Podarcis)

Modern studies have shown how parasites add extra complexity to ecosystems through their potential effects on hosts. Blood parasites are common in lizards and various studies have suggested varying degrees of negative effects on these hosts. In this study, we investigate effects of infection by blood parasites on the boldness and aggressiveness of male lizards of two sympatric species living in North Portugal: Podarcis bocagei and Podarcis lusitanicus, known to host blood parasites of two protozoan orders: Adeleorina and Eimeriorina (Apicomplexa). We used a mirror to quantify behavioural interactions of the lizards with their specular images, which did not identify any influence of parasite infection on either species. Boldness was evaluated through exploratory tests, with an identified trend for parasitized P. lusitanicus towards higher exploratory activity and exposure time. This was independent of the intensity of infection. No such effect was found for P. bocagei. The behavioural changes for infected P. lusitanicus appear to be in the direction of increasing light exposure by spending more time directly under the light source, thus suggesting a link with thermoregulation, although further experiments to clarify this hypothesis are required. These results highlight the importance of understanding individual parasite-host relationships, as they show that the same parasites can have different effects across even closely related species.Significance statementParasites can affect their host in a variety of ways. We used mirror-interaction and exploratory tests to assess the effects of blood parasites in the aggressiveness and boldness behavioural traits of two sympatric lizard species: Podarcis bocagei and Podarcis lusitanicus. No effect of blood parasite infection in these two behavioural traits was identified on Podarcis bocagei. Podarcis lusitanicus tended to demonstrate a response to infection by Adeleorina with an increase in boldness and willingness to increase exposure times, despite low intensity of infection. Our results show how the same parasites can differently affect closely related host taxa from the same system, and how their effects can be significant even when intensities of infection are low.

Reproductive activity of two sympatric lizard species, Ameivula ocellifera and Glaucomastix itabaianensis (Squamata: Teiidae), from Northeastern Brazil

ABSTRACT Reproductive strategies may vary among lizard species, considering environmental as well as phylogenetic effects. Ameivula ocellifera and Glaucomastix itabaianensis are two sympatric lizard species belonging to the family Teiidae, and therefore we assume they exhibit similarities in their reproductive patterns. The objective of the present study was to describe the reproductive activity and evaluate the influence of environmental variables and the body fat cycle on the reproductive activity of these two lizard species. The research was carried out in Pirambu Restinga, Sergipe state, Northeastern Brazil, between 2017 and 2018. Glaucomastix itabaianensis and A. ocellifera displayed seasonal and continuous reproduction, respectively. In both sexes of G. itabaianensis, the lowest fat values coincided with the peak of reproductive activities. The fat body mass of A. ocellifera remained low throughout the year, coinciding with its continuous reproductive activity. Females of A. ocellifera with oviductal eggs were observed in both seasons. The egglaying of G. itabaianensis occurred in the transition period between the dry and rainy seasons, which may be associated with the presence of microclimatic conditions favourable to the embryonic development and survival of the offspring. Despite both belonging to the family Teiidae and being sympatric, the two species showed different reproductive patterns.

High-resolution climate data reveal an increasing risk of warming-driven activity restriction for diurnal and nocturnal lizards.

Widespread species experience a variety of climates across their distribution, which can structure their thermal tolerance, and ultimately, responses to climate change. For ectotherms, activity is highly dependent on temperature, its variability and availability of favourable microclimates. Thermal exposure and tolerance may be structured by the availability and heterogeneity of microclimates for species living along temperature and/or precipitation gradients - but patterns and mechanisms underlying such gradients are poorly understood. We measured critical thermal limits (CTmax and CTmin) for five populations of two sympatric lizard species, a nocturnal gecko (Chondrodactylus bibronii) and a diurnal skink (Trachylepis variegata) and recorded hourly thermal variation for a year in three types of microclimate relevant to the activity of lizards (crevice, full sun and partial shade) for six sites across a precipitation gradient. Using a combination of physiological and modelling approaches, we derived warming tolerance for the present and the end of the century. In the present climate, we found an overall wider thermal tolerance for the nocturnal species relative to the diurnal species, and no variation in CTmax but variable CTmin along the precipitation gradient for both species. However, warming tolerances varied significantly over the course of the day, across months and microhabitats. The diurnal skink was most restricted in its daily activity in the three driest sites with up to six daily hours of restricted activity in the open (i.e. outside refugia) during the summer months, while the impacts for the nocturnal gecko were less severe, due to its higher CTmax and night activity. With climate change, lizards will experience more months where activity is restricted and increased exposure to high temperatures even within the more sheltered microhabitats. Together our results highlight the importance of considering the relevant spatiotemporal scale and habitat for understanding the thermal exposure of diurnal and nocturnal species.

Digestive tract morphology and argyrophil cell distribution of three sympatric lizard species

The digestive tract plays a crucial role in an organism’s health. Here, the digestive tract morphology and argyrophil cell distribution of three sympatric lizard species, Teratoscincus roborowskii, Phrynocephalus axillaris and Eremias roborowskii, were studied. Our results show that T. roborowskii’s snout–vent length (SVL) and digestive tract length (DTL) were significantly longer than those of P. axillaris and E. roborowskii. P. axillaris’ relative intestine length was 1.25, which was significantly longer than those of the other two species. The three lizard species’ digestive tract structures were generally similar, whereas their histologic characteristics exhibited significant differences. Particularly, T. roborowskii’s and P. axillaris’ esophagus mucosa was pseudostratified ciliated columnar epithelium, whereas simple columnar epithelium was observed in E. roborowskii, which also had fewer mucosal folds than the other two species. In all three lizard species, the small intestines’ mucosal lining consisted of simple columnar epithelium with many goblet cells; the largest quantity of villi was found in T. roborowskii. Moreover, T. roborowskii’s mucous membrane (MM) and tunica muscularis (TM) were obviously thicker than those of the other two species. However, the argyrophil cells’ distribution densities of the three species were remarkably different; such differences were highest in the cardia of T. roborowskii and E. roborowskii, but P. axillaris was observed to have more argyrophil cells in its stomach body. Our results indicated that the three lizards’ different histomorphologies might be due to limited food resources, availability of a single food type in the Turpan Basin’s extremely arid and hot environment, as well as T. roborowskii’s special frugivorous behavior. Morphological studies of these lizards are necessary to understand their digestive systems’ structure and operation, as well as to facilitate physiological studies of adaptions to extreme desert habitats.

Selected microhabitat and surface temperatures of two sympatric lizard species

Many small lizards live in structurally and thermally heterogeneous environments where they can select preferred microhabitats and surface temperatures to optimize their activity. We examined microhabitat selection and analyzed surface temperatures selected by two ecologically similar lacertid species, Iberolacerta horvathi and Podarcis muralis, at three sites and in different ecological contexts: allotopic and syntopic conditions. We examined their microhabitat and spatial thermal selection by using high-precision geolocation techniques to locate the lizards and record surface temperatures with temperature data loggers. Microhabitat and thermal availability differed among sites: the I. horvathi allotopic site had more rock surfaces and was coldest; the P. muralis allotopic site had more ground surfaces and was warmer; and the syntopic site had the greatest surface and thermal heterogeneity. Our results highlight the differences in microhabitat selection between the two species, most notably in surface selection, but also in thermal characteristics. I. horvathi preferentially and almost exclusively selected rocks. P. muralis chose soil, but with a more general use of microhabitats. I. horvathi lizards chose colder temperatures than those available, while P. muralis chose higher temperatures than those available. Both species showed no differences in microhabitat selection between allotopic and syntopic sites, which could not be explained by differences between sites. Our results provided new insights into the difference in surface temperature selection between two lizard species that may be adapted to different environments.

Blood parasites in sympatric lizards: what is their impact on hosts’ immune system?

Abstract Assessment of parasites and their pathogenicity is essential for studying the ecology of populations and understanding their dynamics. In this study, we investigate the prevalence and intensity of infection of haemogregarines (phylum Apicomplexa) in two sympatric lizard species, Podarcis vaucheri and Scelarcis perspicillata, across three localities in Morocco, and their effect on host immune response. We used the Phytohaemagglutinin (PHA) skin testing technique to relate the level of immune response with parasite infection. Prevalence and intensity levels were estimated with microscopy, and 18S rRNA gene sequences were used to confirm parasite identity. All parasites belong to the haemogregarine lineage found in other North African reptiles. There were differences in prevalence between localities and sexes. Overall, infected lizards were larger than uninfected ones, although we did not detect differences in parasitaemia across species, sex or locality. The swelling response was not related to the presence or number of haemogregarines, or to host body size, body condition, sex or species. We found no evidence of impact for these parasites on the circulating blood cells or the hosts’ immune system, but more data is needed to assess the potential impact of mixed infections, and the possibility of cryptic parasite species.

Effects of biotic and abiotic stressors on asymmetries and head size in two sympatric lizard species

Abstract Organisms face numerous environmental stressors, which can affect developmental precision, including symmetry of various physical characteristics. Fluctuating asymmetry (FA) has therefore been suggested as a simple and efficient tool for assessing sub-lethal stress levels. We analyzed FA in two sympatric lizard species (Iberolacerta horvathi and Podarcis muralis) to determine potential effects of interspecific competition and urbanization, as proxies of stress, taking into account sexual dimorphism and environmental conditions. We sampled 16 syntopic and allotopic populations and used geometric morphometrics of head morphology. We detected significant but mixed effects on the head asymmetry from the environment and the syntopic occurrence that differed between species. P. muralis lizards had more asymmetric heads at higher altitudes, while I. horvathi lizards did at mid altitudes, which may be explained by P. muralis experiencing environmental stress of colder conditions at higher altitudes. The mid-altitude effect on asymmetries in I. horvathi might be explained by a lower availability of stony walls and higher abundance of P. muralis, thus higher competition. The asymmetry of supraciliary granules was affected by the presence of other species. However, lizards from allotopic populations attained larger asymmetries compared to lizards from syntopic populations, which was the opposite from what was expected. There was no effect of urbanization in P. muralis, which could be due to relatively low pollution and habitat degradation in study locations. Overall, we highlighted the possibility of using lizards and FA for bioindication of environmental stressors and especially improved the knowledge gap in the research of biotic stressors.

Patterns of Visual and Ultraviolet Reflectance in Femoral Gland Secretions of Two Desert Lizards

Femoral gland secretions in lizards convey chemical information about the health and social status of the depositing individual. These secretions influence behaviors related to female mate choice and male–male competition, but little is known about how they are first located by lizards in the environment. Secretions are visually conspicuous and can be sighted from a distance by visually adept lizards, but the specificity of secretion reflectance to the depositing species remains unknown. We examined the reflectance spectra of femoral gland secretions from two sympatric lizard species, Aspidoscelis tigris and Gambelia wislizenii, to determine whether secretions could be visually distinguished. Mean reflectance did not differ between species, but A. tigris had higher reflectance in ultraviolet wavelengths. For both species, lizards in better body condition, as determined by the residuals of the relationship between snout–vent length and body mass, had higher ultraviolet reflectance. In summary, our results indicate that femoral gland secretions can be visually discriminated between species if the discriminating lizard is ultraviolet sensitive.

Does Liolaemus lemniscatus eavesdrop on the distress calls of the sympatric weeping lizard?

For a prey, its best ticket to stay alive is to get early and accurate information on predation risk and so, escape from predation at low cost. Some prey species have evolved the ability to eavesdrop signals intended for others, which contain information on predation risk. This is the case for the vocalizations produced by prey species when interacting with predators. Although primarily studied in birds and mammals, eavesdropping on vocal signals has been recorded in some lizard species. Here, we explored whether the lizard Liolaemus lemniscatus eavesdrops on the distress calls of its sympatric species, the Weeping lizard (L. chiliensis). Individuals of the Weeping lizard respond to these calls by displaying antipredator behaviours (i.e., reduced movement), and individuals of L. lemniscatus may potentially display similar defences if they decode the information contained in these calls. Our playback experiments showed that individuals of L. lemniscatus responded to the sound stimuli (distress calls and white noise), reducing their activity, but they did not discriminate between these two stimuli, suggesting that L. lemniscatus does not eavesdrop on the distress calls of its sympatric lizard species. We discuss some hypotheses to explain the lack of eavesdropping by L. lemniscatus on the Weeping lizard distress calls.

Noninvasive Identification of Herpetofauna: Pairing Conservation Dogs and Genetic Analysis

ABSTRACTNoninvasive fecal sampling combined with genetic analysis is a technique allowing the study of elusive or otherwise difficult to monitor species without the need for direct contact. Although this method is widely used in birds and mammals, it has never been successfully applied on a large scale in reptiles. The blunt‐nosed leopard lizard (Gambelia sila) is an endangered species endemic to the San Joaquin Desert, California, USA. Presently, acquiring data on the species for research and management involves more traditional methods such as live capture or visual surveys, the latter of which are required for regulatory monitoring in accordance with wildlife agency protocols. We used an approach for gathering additional information that combines conservation detection dogs trained to locate blunt‐nosed leopard lizard scat samples with genetic analysis for identifying and distinguishing among sympatric lizard species. We developed 2 polymerase chain reaction assays that produce fluorescently labelled amplicons of species‐specific fragment length for 6 lizard species in the study area. Using these assays, we genetically identified to species 78% (255 of 327) of samples collected by dog‐handler teams across 4 years. The majority of the genetically identified samples (82.4%; 210 of 255) were confirmed as originating from blunt‐nosed leopard lizards. Although an assessment of the viability of detection dogs in regulatory monitoring efforts is required, our ability to recover usable DNA and to differentiate among a diverse group of lizards highlights the broad potential of our methodology for noninvasive sampling in reptiles. © 2019 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

Evidence of character displacement in microhabitat use between two tropical sympatric Holcosus lizard species (Reptilia, Teiidae)

Interspecific competition between sympatric related species leading to character displacement is critical for species coexistence, especially in tropical habitats. We examined microhabitat use of two sympatric species of tropical lizards of the genus Holcosus in relationship to the microhabitats available in two ecosystems. The species H. festivus lives exclusively in the forest and uses microhabitats in proportion to their availability; while the other, H. quadrilineatus, lives both in forest and on the beach and selects microhabitats with specific characteristics. In the ecosystem where these two lizards live in sympatry (forest), we observed a differential microhabitat use between the two species. However, these differences indicated changes in habitat use by H. quadrilineatus (the smaller species) concerning its patterns of habitat selection in the ecosystem (beach) where only this species occurs. The age of the lizards did not affect the patterns of selection of microhabitats of either species. Shifts in microhabitat use may allow coexistence in sympatry of both species, which might result from the competitive exclusion of the smaller species by the larger species. Key words: Interspecific competition, Holcosus, Lizards, Microhabitat use, Tropical habitats

Thermal tolerance in the urban heat island: thermal sensitivity varies ontogenetically and differs between embryos of two sympatric ectotherms.

Most studies of thermal tolerance use adults, but early-life stages (e.g. embryos) are often more sensitive to thermal agitation. Studies that examine effects on embryos rarely assess the potential for thermal tolerance to change with ontogeny or how effects differ among sympatric species, and often utilize unrealistic temperature treatments. We used thermal fluctuations from nests within the urban-heat island to determine how thermal tolerance of embryos changes across development and differs among two sympatric lizard species (Anolis sagrei and Anoliscristatellus). We applied fluctuations that varied in frequency and magnitude at different times during development and measured effects on embryo physiology and survival, and hatchling morphology, growth and survival. Thermal tolerance differed between the species by ∼2°C: embryos of A. sagrei, a lizard that prefers warmer, open-canopy microhabitats, were more robust to thermal stress than embryos of A. cristatellus, which prefers cooler, closed-canopy microhabitats. Moreover, thermal tolerance changed through development; however, the nature of this change differed between the species. For A. cristatellus, thermal tolerance was greatest mid-development. For A. sagrei, the relationship was not statistically clear. The greatest effects of thermal stress were on embryo and hatchling survival and embryo physiology. Hatchling morphology and growth were less affected. Inter-specific responses and the timing of stochastic thermal events with respect to development have important effects on embryo mortality. Thus, research that integrates ecologically meaningful thermal treatments, considers multiple life-history stages and examines interspecific responses will be critical to make robust predictions of the impacts of global change on wildlife.

Motion-based signaling in sympatric species of Australian agamid lizards.

Signaling species occurring in sympatry are often exposed to similar environmental constraints, so similar adaptations to enhance signal efficacy are expected. However, potentially opposing selective pressures might be present to ensure species recognition. Here, we analyzed the movement-based signals of two pairs of sympatric lizard species to consider how reliable communication is maintained while avoiding misidentification. Our novel approach allows us to quantify signal contrast with plant motion noise at any site we measure, including those utilized by other species. Ctenophorus caudicinctus and Gowidon longirostris differed in display complexity and motor pattern use. They also differed in overall morphology, but their signal contrast scores are strikingly similar. These results demonstrate similar adaptations to their shared environment while maintaining species recognition cues. In contrast, Ctenophorus fordi and Ctenophorus pictus are much closer in appearance, but C. pictus produces considerably higher signal contrast scores, which we suggest is attributable to the absence of territoriality in C. fordi. Taken together, our data provide evidence for adaptation to the local environment in movement-based signals, while also meeting species recognition requirements, but the selective pressure to deal with local conditions is mediated by signal function.

Towards a functional understanding of species coexistence: ecomorphological variation in relation to whole‐organism performance in two sympatric lizards

SummaryWe examined intra‐ and interspecific variation in functional morphology and whole‐organism performance in a sympatric lizard species pair,Iberolacerta horvathiandPodarcis muralis, in the area with a high potential for competition.The biggest variation between species was found in two functional traits, bite force and climbing speed, linked with corresponding morphological traits.The species with larger and taller heads,P. muralis, exhibited correspondingly stronger bite forces. The other species exhibited smaller and flatter head. Both traits may potentially promote segregation between species in trophic niche (stronger bites relate to harder prey) and in refuge use (flatter heads allow using narrower crevices, hence, influencing escaping from common predators). Stronger bites and larger heads also provide one species with a dominant position in interspecific agonistic interactions.Females had longer trunks that impacted negatively on climbing speed, which may lower anti‐predator escape abilities of the more trunk‐dimorphic species, but positively influence reproductive effort.Our results exemplify how the joint examination of morphological and functional traits of ecologically similar and sympatric species can provide a mechanistic background for understanding their coexistence, namely, syntopic populations that are frequent in the study area.The identified roles of functional morphology in this system of sympatric rock lizards support the contribution of functional diversification for the complexity of community structure via coexistence.Alay summaryis available for this article.

The latitudinal diversity gradient and interspecific competition: no global relationship between lizard dietary niche breadth and species richness

AbstractAimDietary niche breadth has long been hypothesized to decrease towards lower latitudes as the numbers of competitors increase. Geographical variation in niche breadth is also hypothesized to be linked to high ambient energy levels, water availability, productivity and climate stability – reflecting an increased number of available prey taxa. Range size and body size are also hypothesized to be strongly and positively associated with niche breadth. We sought to determine which of these factors is associated with geographical variation in niche breadth across broad spatial scales and thus potentially drive the latitudinal diversity gradient.LocationGlobal.MethodsWe collated volumetric dietary data for 308 lizard species. For each species, we gathered data on number of sympatric lizard species (a proxy for the number of competitors), annual temperature and precipitation, net primary productivity, seasonality, range size and body size. We examined the relationship between dietary niche breadth and focal parameters using both ordinary and phylogenetic generalized least squares regressions.ResultsNiche breadth was positively related to annual precipitation, temperature seasonality and range size, and negatively related to body size. Lizard species richness increased towards lower latitudes. Dietary niche breadth, however, was unrelated to parameters reflecting diversity gradients, such as primary productivity, annual temperature, precipitation seasonality and, crucially, the number of potential competitors.Main conclusionsContrary to prevailing ecological theory, competition is unrelated to dietary niche breadth. We found no support for interspecific competition driving the latitudinal diversity gradient. Rather, we found variation in niche breadth to be associated with water availability, climate stability, range size and body size. Our study casts doubt on the common assumption that tropical species are specialists, promoting greater alpha diversity, and on the assumption that the number of sympatric species is reflected in the intensity of interspecific competition.

When invasion may not be harmful: niche relations in a lizard assemblage

Some studies have suggested that non-native species invasions may threaten local diversity by creating homogenized environments. However, many studies have been based on limited or anecdotal data, and/or have failed to consider the influence of habitat modification together with possible influences of non-native species on native ones. Hemidactylus mabouia (Squamata, Gekkonidae) likely invaded natural environments in Brazil hundreds of years ago. Yet, little is known about whether it affects native lizard fauna. We tested whether H. mabouia negatively influences native lizard species richness and abundance on a regional scale and locally through niche overlap. We analyzed species abundance and richness of nine lizard assemblages, in five of which H. mabouia occurred. We evaluated niche overlap of species in a lizard assemblage with high H. mabouia abundance through null models. Niche axes included spatial use, temporal activity and diet. Although species abundance did not differ among sites with and without the invasive species, the presence of H. mabouia seems constrained to the richer assemblages sampled. We observed significantly higher niche overlap in spatial (ɸobs = 0.63; ɸexp = 0.37; Pobs ≥ Pexp = 0.0002) and trophic axes (ɸobs = 0.46; ɸexp = 0.17; Pobs ≥ Pexp < 0.001), but not in activity. When we considered all axes (three-dimensional niche), there was no overlapping among the lizard species. Our findings did not support the hypothesis that this non-native species negatively influences other sympatric lizard species.

Trophic ecology of two sympatric lizard species: the Algerian sand lizard and the wall lizard in Djurdjura, northern Algeria

AbstractIn this study, we present the first data on the diet of two sympatric lizard species Psammodromus algirus and Podarcis vaucheri of the Djurdjura Mountains. The analysis of 100 feces (43 Ps. algirus and 57 P. vaucheri) allowed us to identify 560 prey items (254 for Ps. algirus and 312 for P. vaucheri) distributed across 17 operational taxonomic units. Insects were most commonly consumed by both species, but spiders were also preferred by P. vaucheri. The five most commonly ingested categories of prey among insects were: Coleoptera, Hymenoptera, Homoptera, Heteroptera and Orthoptera. During the study period, the interspecific diet overlap was very high (CH = 0.86). But the diet of P. vaucheri (BA = 0.50) was slightly more diversified than that of Ps. algirus (BA = 0.41). The diets of both species were, however, not strongly different. A significant influence of seasonal variation on diet was detected.

Does population size affect genetic diversity? A test with sympatric lizard species.

Genetic diversity is a fundamental requirement for evolution and adaptation. Nonetheless, the forces that maintain patterns of genetic variation in wild populations are not completely understood. Neutral theory posits that genetic diversity will increase with a larger effective population size and the decreasing effects of drift. However, the lack of compelling evidence for a relationship between genetic diversity and population size in comparative studies has generated some skepticism over the degree that neutral sequence evolution drives overall patterns of diversity. The goal of this study was to measure genetic diversity among sympatric populations of related lizard species that differ in population size and other ecological factors. By sampling related species from a single geographic location, we aimed to reduce nuisance variance in genetic diversity owing to species differences, for example, in mutation rates or historical biogeography. We compared populations of zebra-tailed lizards and western banded geckos, which are abundant and short-lived, to chuckwallas and desert iguanas, which are less common and long-lived. We assessed population genetic diversity at three protein-coding loci for each species. Our results were consistent with the predictions of neutral theory, as the abundant species almost always had higher levels of haplotype diversity than the less common species. Higher population genetic diversity in the abundant species is likely due to a combination of demographic factors, including larger local population sizes (and presumably effective population sizes), faster generation times and high rates of gene flow with other populations.

Indirect evidence of predation and intraspecific agression in three sympatric lizard species from a semi-arid area in northeastern Brazil

We analyzed the frequency of tail autotomy, toe amputation and integument scars in three sympatric lizard species, Ameivula ocellifera, Tropidurus hispidus and T. semitaeniatus, from a Neotropical area of semi-arid Caatinga, in northeastern Brazil. We evaluated intraspecific differences in the frequency of injuries between the sexes within each species. Only in A. ocellifera there were differences in frequency of toe amputation and integument scars between males and females, with more injured females than males. This highest frequency of body injuries in females of A. ocellifera might be attributed to the mating behavior of the species, in which males bite and scratch the females. None of the species analyzed presented intersexual differences in frequency of tail autotomy. These findings might be due to similar predation pressure upon males and females as suggested for other lizards species.

Booming during a bust: Asynchronous population responses of arid zone lizards to climatic variables

The productivity of arid environments and the reproductive success of vertebrates in these systems, are typically thought to be primarily influenced by rainfall patterns. Data from our 15 year study at an Australian arid zone site reveals asynchronous demographic responses to rainfall and other climatic variables among different lizard species. We show that, in addition to precipitation, key demographic rates (fecundity, recruitment and survival) are correlated strongly with temporal variability in temperature, during and prior to the breeding season, and also to the density of sympatric lizard species. There were nine-fold fluctuations through time in the relative abundance of two similar-sized Ctenotus species, and asynchronous recruitment success and survival among other species, despite the absence of direct anthropogenic affects Understanding the drivers and magnitude of the substantial natural variability in arid-zone lizard assemblages is integral to predicting and interpreting their responses to future land use or climate-change scenarios.