The spatial ecology of animals is influenced by the structure of their physical habitat, which affects the availability of refuges and microclimate, as well as the spatial positioning of resources. The use of space by the lizard Liolaemus tandiliensis was investigated in the Tandilia mountains of the Pampas region. We radio-tracked 19 adult lizards and found that home range size and distance moved were significantly affected by sex, with males having a home range 34% larger and moving longer distances than females. These parameters were also influenced by structural and thermal features of specific microhabitat types. The habitat structure inside the home range showed relatively high coverage of rocks and low coverage of vegetation. The thermal properties of the microhabitats were strongly associated with their occupancy; individuals used microhabitats of high thermal quality that exhibited environmental temperatures deviating the least from the preferred body temperature range of L. tandiliensis. . Small-scale structural heterogeneity and thermal gradients were available in the Tandilia mountains, so L. tandiliensis individuals may not need to move large distances and may sustain themselves within a relatively small home range (mean=74.52 m2). 2 ). Our findings suggest that L. tandiliensis occurs in a delicate balance with its specific habitat. This study provides information that must be taken into account for conservation planning, especially in light of the increasing anthropogenic degradation of the Tandilia mountains.

Predicting the probability of species occurrence based on environmental variables across landscapes makes it possible to determine suitable habitats and constitutes an important tool for identifying priority areas for conservation. Sand Dune Lizards (Liolaemus multimaculatus) are endemic to the temperate coastal dunes from Argentina and were recently classified as Endangered by the International Union for Conservation of Nature. We studied the influence of landscape metrics on this lizard's distribution and built predictive distribution maps from habitat suitability models. Additionally, we analyzed the representation of suitable habitats within natural protected areas (NPAs). We conducted lizard surveys in two successive seasons and obtained landscape metrics from thematic maps in two circular landscape units. All information collected was compiled into a Geographical Information System (GIS). The relationships between lizard presence or absence and the landscape metrics were analyzed using Generalized Linear Models, and the results were transferred using GIS to habitat suitability maps. Digitalized NPAs were overlapped on these maps to estimate the representation of suitable habitats. Within the main habitat categories of the sand dunes, L. multimaculatus was found exclusively in active dunes, which means that these habitats are of vital importance for this species. The habitat suitability models indicated that (1) patch size of active dunes and distance to the coastline were the main drivers of the distribution of this species, and (2) homogeneous landscapes composed of active dunes and low or null percentages of semi-fixed and forested dunes were the preferred habitat. The predictive maps showed that highly suitable habitats encompass <5% (2059.7 ha) of total active dunes and had a linear distribution near the coastline and far away from areas modified by human activities. Currently, only 19.8% (408.8 ha) of highly suitable habitats fall within NPAs boundaries. The high habitat association of the species and the very small remaining suitable habitat warrants urgent conservation measures, which can be supported by habitat suitability models based on landscape metrics.

Physiological performance in lizards may be affected by climate across latitudinal or altitudinal gradients. In the coastal dune barriers in central-eastern Argentina, the annual maximum environmental temperature decreases up to 2°C from low to high latitudes, while the mean relative humidity of the air decreases from 50% to 25%. Liolaemus multimaculatus, a lizard in the family Liolaemidae, is restricted to these coastal dunes. We investigated the locomotor performance of the species at 6 different sites distributed throughout its range in these dune barriers. We inquired whether locomotor performance metrics were sensitive to the thermal regime attributable to latitude. The thermal performance breadth increased from 7% to 82% with latitude, due to a decrease in its critical thermal minimum of up to 5°C at higher latitudes. Lizards from high latitude sites showed a thermal optimum, that is, the body temperature at which maximum speed is achieved, up to 4°C lower than that of lizards from the low latitude. At relatively low temperatures, the maximum running speed of high-latitude individuals was faster than that of low-latitude ones. Thermal parameters of locomotor performance were labile, decreasing as a function of latitude. These results show populations of L. multimaculatus adjust thermal physiology to cope with local climatic variations. This suggests that thermal sensitivity responds to the magnitude of latitudinal fluctuations in environmental temperature.

The behavioral and physiological mechanisms of thermoregulation and the morphological traits of lizards result in a particular range of body temperatures, which influence performance and ultimately fitness. We studied the thermal biology and locomotor performance of the lizard Liolaemus wiegmannii from the coastal dunes in the southeastern Pampas of Argentina. During the austral summer, we examined the link between thermoregulation and optimal locomotor performance. Liolaemus wiegmannii faced a stressful environment due to high risk of overheating; despite this, the species was able to achieve field body temperatures (Mean Tb ± SD = 35.58 ± 2.86 °C) than expected by chance (i.e., the null model) and suitable for sustaining its physiological performance. Locomotion in this species was thermally-sensitive, with lizards showing high-performance bouts at a relatively wide range of body temperatures (30-38 °C). Lizards exhibited a mean maximum running speed of 1.30 m/s at 37.3 °C (i.e., optimal temperature for locomotion) which was within the set point range of preferred temperature (Tset = 35.4-37.5 °C). Therefore, we found a correspondence between thermal optimum and preferred temperature. Our findings suggest that L. wiegmannii, like other lizard species with a broad distribution, is capable of performing well across a wide range of temperatures despite the spatiotemporal thermal fluctuations of the environment.

Fil: LUCIFORA, Luis Omar. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Santa Fe. Instituto Nacional de Limnologia. Universidad Nacional del Litoral. Instituto Nacional de Limnologia; Argentina

Thermoregulation in ectotherms may be modulated by climatic variability across geographic gradients. Environmental temperature varies along latitudinal dines resulting in heterogeneous thermal resource availability, which generally induces ectotherms to use compensatory mechanisms to thermoregulate. Lizards can accommodate to ambient temperature changes through a combination of adaptive evolution and behavioral and physiological plasticity. We studied the thermal ecology of the endangered endemic lizard Liolaemus multi-maculatus at six different sites distributed from the northern to southern areas of the distribution (700 km) in the Atlantic dune barriers of Argentina, and even including the borders areas of the distribution range. Environmental temperatures and relative humidity showed a strong contrast between northern and southern limits of the distribution range. The northern localities had operative temperatures (Te) above the range of preferred temperatures (Tset), instead, the southern localities had large proportion of Tes within the Tset. Although these different climatic conditions may constrain the thermal biology of L. multimaculatus, individuals from all localities maintained relatively similar field body temperatures (XTb = 34.07 +/- 3.02 degrees C), suggesting that this parameter is conservative. Thermal preference partially reflected latitudinal temperature gradient, since lizards from the two southernmost localities showed the lowest Tsel and Tset. Thermoregulatory efficiency differed among localities, since E values in the northern localities (E = 0.53-0.69) showed less variability than those of southern localities (E = 0.14-0.67). Although L. multimaculatus employed a strategy of having a conservative Tb and being able to acclimatize the thermal preference to copes with latitudinal changes in the thermal environment, other local factors, such as ecological interactions, may also impose limitations to thermoregulation and this may interfered in the interpretation of results at wider spatial scale.

Fil: Vega, Laura Estela. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Postural adjustments and microhabitat selection are two behavioral mechanisms that lizards extensively use to regulate their body temperatures. The Bogert effect occurs when behavioral thermoregulation buffers potential changes in body temperatures of congeneric organisms due to environmental variation, in turn precluding physiological evolution. We compared field body temperatures (Tb) and behavioral thermoregulation traits between two Liolaemus lizards: the saxicolous Liolaemus tandiliensis and the arenicolous Liolaemus wiegmannii. These species are spatially segregated in two thermally contrasting environments from the SE of the temperate Pampas of Argentina. During summer, the mean operative temperature (Te) of the coastal sand dunes occupied by L. wiegmannii was 9 oC higher than that of the Tandilia mountains inhabited by L. tandiliensis. Despite the contrasting thermal conditions of both habitats, the mean Tb of L. tandiliensis (34.72 degrees C) was similar to that of L. wiegmannii (35.01 degrees C). The behavioral thermoregulation mechanisms varied considerably between both species. Liolaemus tandiliensis combined static body posture with displacements towards sunlit areas. In contrast, L. wiegmannii combined elevated and prostrated body postures with movements towards full and filtered sun patches. Environmental gradients offer diverse challenges impelling lizards to find different behavioral thermoregulation adaptations in order to partially cope with environmental constraints. This occurs in many species of Liolaemus that are thermoregulatory efficient despite of the climatic adversities. In this study, two species of Liolaemus used different postural and microhabitat path-selection strategies according to climate, allowing them to buffer changes in Tb, thus suggesting that the Bogert effect may be occurring in these two species.

Small lizards can accommodate to constraints imposed by temporal changes in ambient temperature through a combination of adaptive evolution and behavioral and physiological plasticity. Thermal physiology plasticity may compensate for climate variation and favor performance while minimizing behavioral costs in sub-optimal conditions. The Tandilia's lizard, Liolaemus tandiliensis, occurs in an isolated mountain range of the Argentinean temperate Pampas. In this study, we compared the thermal biology of L. tandiliensis between late spring (December) and mid-summer (February). The habitats' thermal quality was lower in late spring than in mid-summer. The lizard's field-body temperature (Tb) was 2-3 degrees C higher than the operative temperature (Te). Overall, the mean preferred temperature (Tsel) was 37.4 degrees C [preferred range (Tset): 36.2-38.7 degrees C], and was similar to other Liolaemus species. The Tset and Tsel of females in late spring were 1.8 degrees C lower than in mid-summer. In the case of males, the Tsel did not vary among seasons, while the Tset had a difference of 2.5 degrees C between seasons. Adults were moderate thermoregulators, but females were more efficient only in late spring (E-males = 0.69; E-females = 0.58), compared to mid-summer (E-males = 0.68; E-females = 0.50). Juveniles did not show temporal differences in temperature preferences and had a relatively higher efficiency in late spring (E = 0.38) compared to mid-summer (E = 0.28). An increased proportion of juveniles and adults shifted their Tb near to the Tset in late spring respect to mid-summer. The adults also matched their preferred temperatures to their current body temperature. These results suggest that seasonal shifts in the thermoregulatory parameters of L. tandiliensis may improve their thermoregulatory efficiency. Although temporal variation in ambient temperatures might influence the thermal biology of the studied lizards, other factors such as changes in the reproductive status may have also interfered.

We describe a new species of Liolaemus of the L. alticolor-bibronii group of the subgenus Liolaemus sensu stricto. We studied meristic, morphometric and qualitative pattern characters. Statistical tests were performed in order to evaluate morphological differences among the candidate species and the most closely geographically distributed species. Molecular analyses of Cyt-b mitochondrial gene were performed in order to estimate the position of the new species in relation to other taxa. We also recorded natural history data such as habitat, behavior, reproductive state, diet, and body temperature. Liolaemus absconditus sp. nov. differs from other species of Liolaemus in presenting a distinct combination of morphological character states of lepidosis and color pattern, being phylogenetically close to Liolaemus tandiliensis, Liolaemus gracilis and Liolaemus saxatilis. The new species is a saxicolous and endemic lizard of the Tandilia Mountain Range System of Buenos Aires Province.

Home ranges of lizards are the result of both internal (body condition, reproductive status) and external factors, such as habitat features and resource availability. Habitat modification induced by introduced plants affects habitat use for lizards by changing food abundance, environmental temperatures or by homogenising the habitat structure. We compared the home range of the lizard Liolaemus wiegmannii in two situations: a partially forested habitat (20% of the total surface covered by Acacia longifolia) and a non-forested habitat. Twelve adult lizards were radio-tracked in the forested habitat and ten in the non-forested site. Home ranges were calculated using the minimum convex polygon method. The mean home range size was 37.80 +/- 17.95 m(2) and was not different between both habitat types. Home ranges of males were 1.6 times larger than those of females. Abundance of food was highest in the forested habitat, without an apparent effect on home range size. Home range in L. wiegmannii showed a marked association with mixed patches of native grassland, bare sand substrates and scarce coverage of exotic trees. Our data suggest that movements in L. wiegmannii may be mainly related to structural features (and their associated thermal cues) of specific microhabitat types. Although low levels of forestation with A. longifolia have less effect on the home range size and movements of lizards, we cannot ignore previous results showing that occurrence, abundance and body condition of L. wiegmannii are negatively affected by extensive forestation of exotic plants both at local and landscape scales in pampasic dunes.

The knowledge of environmental variables associated with the species occurrence allows the recognition of sites which fulfil ecological requirements eventually used for conservation of species. The coastal dunes of Argentina are inhabited by sand lizards. Anthropic activities have severely degraded this ecosystem, affecting the habitat structure at a large scale. In this context, the effects of landscape characteristics on the sand lizard's (Liolaemus wiegmannii, Liolaemidae) presence were analysed to build habitat suitability maps along the coastal dunes of Argentina. A thematic map of study area was obtained from supervised classification of satellite images to identify landscape characteristics. Surveys were conducted during the lizard activity season, and landscape variables were measured in two spatial units. All information collected was compiled into a Geographic Information System. The relationship between the presence of lizards and landscape variables was evaluated by Generalized Linear Models. The predictions of these models were transferred by using Geographic Information System to habitat suitability maps. Almost all individuals (80%) were observed in semi-fixed dunes. The analysis of landscape metrics in the two spatial extents showed complementary results. The habitat suitability models suggest that: (i) heterogeneous landscapes composed by disaggregated patches of semi-fixed dunes and low or null percentages of active dunes distant from the coastline are the preferred environments, and (ii) human modifications such as urbanizations and forestation of dunes, have a negative impact on species occurrence. Suitable habitats were almost absent in those sectors of coastal dunes with highest level of urbanization, whereas they were distributed almost continuously in those areas without human disturbances.

Animal habitat-use patterns cannot be isolated from scale issues. Consequently, multi-scale studies provide a complete characterization of ecological patterns that can further explain the observed variation. Liolaemus constitutes the world's second most speciose lizard genus. In this study, we assessed the relationships between home range size and environmental variables at 3 different spatial scales. The study at a local and regional scale was focused on the habitat specialist Liolaemus multimaculatus. The lizard's home range was calculated using the minimum convex polygon method in populations from grassland sites of the coastal sand dunes of the Argentinean Pampas under 2 different conditions, with or without forestations of Acacia longifolia. On the other hand, at a geographical scale we considered the evolutionary implications of 20 species of Liolaemus. Home range size, phylogeny, ecological, environmental, and climatic data were obtained from the literature and remote sensing. L. multimaculatus home range varied from 12.66 to 570.00 m. Regionally, this species had smaller home ranges in forested habitats ([Formula: see text]: 94.02 m2) compared with the non-forested sites ([Formula: see text]: 219.78 m2). Habitat structure, vegetation types, and food availability would explain the space use at finer scales. When the 20 species of Liolaemus were considered, high mean air temperature and broad thermal amplitudes showed an inverse relationship with home range size. Neither net primary productivity nor phylogeny was good predictors for home range variation at geographical scale. This study highlights the scale dependence of the explicative capability of a set of environmental and intrinsic variables on home range patterns.

Fil: Block, Carolina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

A pesar del avance en el conocimiento de la biodiversidad para ciertas regiones, éste se encuentra en general disperso y no ha sido interpretado respecto a sus propiedades emergentes ni puesto en contextos que faciliten la toma de decisiones en conservación. El sudeste de la ecorregión Pampas presenta una diversidad ambiental destacada en un área relativamente restringida, y existe además una importante cantidad de información sobre diversidad de Tetrápodos. Nuestro objetivo fue compilar y analizar este cúmulo de información, a través de una lista de especies con sus abundancias relativas por ambientes destacando aquellas endémicas y de interés para la conservación. Evaluamos la complementariedad entre los taxa (anfibios, reptiles, aves y mamíferos) en términos de composición, número de especies totales y amenazadas. La diversidad de Tetrápodos recopilada pone de manifiesto que esta pequeña área presenta una importante riqueza de especies (12 especies de anfibios, 26 reptiles, 233 aves, 34 mamíferos; 41 están amenazadas y tres son endémicas). Los ambientes representados (pastizales, dunas, sierras, humedales, estuarios, marino, agroecosistemas, urbanizaciones) contribuyen diferencialmente a la diversidad general de Tetrápodos. La distribución desproporcionada de la riqueza de especies, de especies amenazadas y de la composición entre ambientes dentro de cada taxón, entre taxa y entre diferentes unidades ambientales destacan la utilidad de este tipo de análisis en la interpretación de la variación espacial de la biodiversidad y deberían contribuir en la planificación territorial en un marco que optimice la conservación.

The introduction of nonnative plant species might generate habitat modifications that, in turn, increase the predation risk for animals, either by making prey species more conspicuous, limiting the availability of refuges, or by offering vantage points to potential predators. We compared predation pressure and escape behavior of two sympatric species (Liolaemus wiegmannii and Liolaemus multimaculatus) of Sand Lizards inhabiting forested and nonforested grasslands of the pampasic coastal sand dunes of Argentina. Predation pressure was evaluated by measuring the predation rate on plasticine replicas of lizards and the abundance of avian predators. We also recorded flight initiation distance (FID) of lizards in the different habitat types and the microhabitat used as refuge. Both lizard species prefer refuges in native plants but, when they are scarce, the nonnative Acacia longifolia is selected as alternative refuge. In forested habitats, sand-burying behavior is a complementary strategy used by L. multimaculatus to avoid predation. The FID of L. wiegmannii was greater in forested habitats than in nonforested ones. In contrast, L. multimaculatus exhibited a short FID in forested habitats, mostly because sand-burying behavior appears to reduce the risks typically associated with exposed areas. Plasticity in antipredatory behavior suggests that these lizards could recognize predators and develop a suitable antipredatory behavior. We conclude that increased predation pressure and structural alterations of the habitat in the presence of nonnative A. longifolia affect the decisions that determine how, when, and where these lizards flee.

Context Exotic forestations may modify habitat quality, affecting native animal populations that require specific microhabitats to remain viable. Aims We determined whether abundances and body condition of the lizard species Liolaemus wiegmannii and L. multimaculatus differed between forested and non-forested dunes. We also examined what environmental attributes are important in explaining the potential differences. Methods We sampled six sites of 300 ha each. Three of these sites had original vegetation and three were forested with exotic Acacia longifolia. We traced 120 transects per site searching for lizards. Key results Lizards were two times more abundant in non-forested sites than in sites covered by acacia trees (even as low as a fourth of the area). Sites with high densities of acacia (≥78% of coverage) had the lowest abundance of lizards. In forested sites, the snout–vent length of L. wiegmannii was 10% smaller and relative body mass 22% lower than in non-forested sites. We found no differences in the body size of L. multimaculatus. Conclusions The replacement of the native vegetation by A. longifolia has negative effects on lizard species, representing a substantial threat to L. wiegmannii and particularly to L. multimaculatus, a threatened status species. Structural and thermal characteristics of the non-forested sites seemed to be more favourable for the abundance and body condition, whereas the dense vegetation and the low temperatures on the forested sites might explain the lower presence of lizards. Implications We recommend that before the implementation of future forestation plans in the pampasic coastal dunes, the deleterious consequences that this practice generates on native lizard fauna must be considered. When necessary, we recommend that A. longifolia be planted so that the coverage does not exceed a quarter of the total area, so as to prevent the formation of continuous (or closed) forest patches and to maintain the structural heterogeneity of the habitat that these lizards need to survive. In the most affected areas, eradication and control strategies may help reduce the advancement of this exotic plant over the areas intended for conservation.

Se menciona el hallazgo de una nueva localidad para L. wiegmannii en la Patagonia argentina, precisamente en el Departamento de General Conesa, provincia de Rio Negro. Se remarca la importancia que tiene este nuevo punto respecto de la distribucion actual conocida para la especie en Argentina, ademas se detallan algunas caracteristicas del lugar de colecta.

The present study describes and compares the thermal behavior of individuals of Liolaemus wiegmannii, inhabiting patches of natural grassland and modified patches with exotic trees of Acacia longifolia, by analyzing the factors affecting its behavior. Thermal behavior of L. wiegmannii was assessed by radiotracking 22 adult individuals in a coastal dune area from Argentina. In order to account for individual responses we analyzed the factors affecting thermal behavior using Generalized Linear Mixed Models. Thermal behavior of L. wiegmannii was mainly affected by the time of day and the substrate temperature. The individuals basking on bare sand in the morning shifted to filtered sunlight during midday and to the shade of clump and erect stems and herbs during the afternoon. The individuals buried in sand when the substrate temperature was low and the wind speed was high. The use of sub-shrubs and shrubs could not be explained solely by thermal factors. In natural L. wiegmannii regulated its body temperature by shuttling between microhabitats that provided them with different levels of exposure to sunlight during the day. However, in modified patches individuals varied in the choice of plants used as shaded places to mitigate high microenvironmental temperatures and they were also more exposed to full shaded sites and less to warm sand to bask, which could have negative consequences for its thermal biology.