Thermo-physiological changes and reproductive investment in a liolaemid lizard at the extreme of the slow-fast continuum.

Gravid female lizards often experience reduced thermal preferences and impaired locomotor performance. These changes have been attributed to the physical burden of the clutch, but some authors have suggested that they may be due to physiological adjustments. We compared the thermal biology and locomotor performance of the lizard Liolaemus wiegmannii 1 week before and 1 week after oviposition. We found that gravid females had a thermal preference 1°C lower than that of non-gravid females. This was accompanied by a change in the thermal dependence of maximum running speed. The thermal optimum for locomotor performance was 2.6°C lower before oviposition than after. At relatively low temperatures (22 and 26°C), running speeds of females before oviposition were up to 31% higher than for females after oviposition. However, at temperatures above 26°C, females achieved similar maximum running speeds (∼1.5 m s-1) regardless of reproductive stage. The magnitude of the changes in thermal parameters and locomotor performance of L. wiegmannii females was independent of relative clutch mass (clutches weighed up to 89% of post-oviposition body mass). This suggests that the changes are not simply due to the clutch mass, but are also due to physiological adjustments. Liolaemus wiegmannii females simultaneously adjusted their own physiology in a short period in order to improve locomotor performance and allocated energy for embryonic development during late gravid stage. Our findings have implications for understanding the mechanisms underlying life histories of lizards on the fast extreme of the slow-fast continuum, where physiological exhaustion could play an important role.

Nicho trófico y bioclimático de dos especies andinas cercanamente emparentadas de Liolaemus (Squamata, Liolaemidae) en el sur del Perú / Trophic and bioclimatic niche of two closely related Andean species of Liolaemus (Squamata, Liolaemidae) in southern Peru

Resumen En el presente estudio, los nichos trófico y bioclimático de Liolaemus annectens y L. etheridgei son evaluados. Ambas especies se distribuyen en la región andina del sur del Perú. La comparación interespecífica del nicho trófico reveló a Lygaeidae (Hemiptera) como presa fundamental de L. etheridgei, mientras que las presas fundamentales en la dieta de L. annectens fueron larvas de Lepidoptera, Araneae, Curculionidae (Coleoptera) y Lygaeidae. Asimismo, se observó un importante consumo de material vegetal en ambas especies, por lo que pueden considerarse omnívoras. Ambas especies presentaron una baja amplitud de nicho trófico, con una tendencia especialista de consumo de presas, y un bajo solapamiento de nicho trófico. En cuanto al nicho Grinnelliano, la evaluación y comparación de modelos de nichos ecológicos, permitieron identificar las áreas de mayor idoneidad para la sobrevivencia de estas especies. Estas se encuentran en áreas de Arequipa, Moquegua y Tacna para L. etheridgei y en Arequipa, Puno, y Cusco para L. annectens. Ambas especies mostraron una baja superposición de nicho ecológico, rechazando la hipótesis de que ocupan nichos idénticos.

Abstract In the present study, the trophic and bioclimatic niches of Liolaemus annectens and L. etheridgei are evaluated. Both species are distributed in the Andean region of southern Peru. Interspecific comparison of the trophic niche revealed Lygaeidae (Hemiptera) as a fundamental prey for L. etheridgei, while the fundamental preys in the diet of L. annectens were Lepidoptera larvae, Araneae, Curculionidae (Coleoptera), and Lygaeidae. Additionally, a significant consumption of plant material was observed in both species, indicating an omnivorous diet. Both species exhibited a narrow trophic niche breadth, with a specialist tendency in prey consumption and low trophic niche overlap. Regarding the Grinnellian niche, evaluation and comparison of ecological niche models allowed the identification of areas of highest suitability for the survival of these species. These include some areas in Arequipa, Moquegua and Tacna for L. etheridgei, and some areas in Arequipa, Puno and Cusco for L. annectens. Both species showed low ecological niche overlap, rejecting the hypothesis of identical niches.

Phylogenetic Analyses of Lizards from the Chilean Humboldt Archipelago Reveal a New Species for the Chañaral Island (Squamata: Liolaemidae).

The Humboldt Archipelago, situated on Chile's north-central coast, is renowned for its exceptional biodiversity. However, lizards of the Liolaemus genus are a particularly understudied group in this archipelago. Liolaemus genus is divided into two clades: chiliensis and nigromaculatus. Within the nigromaculatus clade the zapallarensis group is restricted to the semi-arid and arid coastal habitats of the Atacama Desert in north-central Chile. While it has been reported that lizards from the zapallarensis group inhabit various islands within the Humboldt Archipelago, there has been limited knowledge regarding their specific species identification. To identify the lizard species inhabiting these islands, we conducted phylogenetic analyses using a mitochondrial gene and examined morphological characteristics. Our findings reveal that lizards from the Damas, Choros, and Gaviota islands belong to Liolaemus silvai. In contrast, the lizards on Chañaral Island form a distinct and previously unrecognised group, clearly distinguishable from Liolaemus silvai. In conclusion, our study not only confirms the presence of L. silvai on the Damas, Choros, and Gaviota islands but also describes a new lizard species on Chañaral Island named Liolaemus carezzae sp. nov. These findings contribute valuable insights into the biodiversity of these islands and introduce a newly discovered endemic taxon to the region, enriching our understanding of Chile's unique island ecosystems.

Nuevo registro de Liolaemus warjantay (Reptilia, Liolaemidae) y comentarios sobre el grupo montanus en Perú

Se registra Liolaemus warjantay para el departamento de Ayacucho, una especie conocida anteriormente solo para Arequipa. La nueva población es identificada en base a secuencias de ADN y se muestra su variación morfométrica y merística. También, se realizan comentarios sobre las especies recientemente descritas del grupo montanus de Perú.

Liolaemus warjantay is recorded in the Ayacucho department, a species previously known only from Arequipa. The new population is identified based on DNA sequences, also its morphometric and meristic variability is presented. Additionally, comments are made regarding recently described species within the montanus group in Peru.

Tetrathyridia in an endemic lizard from Chile: molecular evidence for South America.

Mesocestoides is a controversial tapeworm with significant lack of data related to systematics and life cycles. This helminth has an indirect life cycle with vertebrates, mostly carnivorous mammals, as definitive hosts. Theoretically, a coprophagous arthropod would be the first intermediate host, and herptiles, mammals, and birds, which prey on these insects, would represent the second intermediate hosts. However, recent evidence suggests that this life cycle would require only two hosts, with no arthropods involved. In the Neotropics, although there are records of mammals and reptiles as hosts for Mescocestoides, no molecular analyses have been performed. This work aimed to record an additional intermediate host and molecularly characterize the isolated larvae. Thus, 18 braided tree iguanas (Liolaemus platei) from Northern Chile were collected and dissected during 2019. One lizard was parasitized by three morphotypes of larvae compatible with tetrathyridia of Mescocestoides. To achieve its specific identity, a molecular approach was performed: 18S rRNA and 12S rRNA loci were amplified through cPCR. The inferred phylogenies confirmed the morphological diagnosis and stated that all morphotypes were conspecifics. The sequences for both loci formed a monophyletic clade with high nodal support, representing a sister taxon to Mescocestoides clade C. This study represents the first molecular characterization of any taxon of Mescocestoides from the Neotropics. Future surveys from potential definitive hosts would help to elucidate its life cycle. Furthermore, an integrative taxonomic approach is required in additional studies from the Neotropical region, which would contribute to a better understanding of the evolutionary relationships of this genus.

Microhabitat use, daily activity pattern, and diet of Liolaemus etheridgei Laurent, 1998 (Reptilia: Liolaemidae) in the Andean Polylepis forests of Arequipa, Peru.

This study describes the microhabitat use, daily activity pattern, and diet of Liolaemus etheridgei Laurent, 1998 in the El Simbral and Tuctumpaya Polylepis forests in Arequipa, Peru. El Simbral is a fragmented forest, whereas Tuctumpaya is unfragmented. Our results reveal that L. etheridgei shows no positive selection for any of the microhabitats we identified in Polylepis forests; on the contrary, it selects negatively against Polylepis trees and nonthorny bushes. The daily activity patterns indicate a bimodal pattern with peaks at 9:00-10:59 and 13:00-13:59 h. The diet of L. etheridgei consists mainly of plant material, and the most important animal prey category is Lygaeidae: Hemiptera, which is selected for positively. In particular, microhabitat selection varied for nonthorny bushes, which were selected negatively in the Tuctumpaya population but neither positively nor negatively in the El Simbral population. According to the proportions of plant material found, the L. etheridgei from El Simbral were found to be omnivorous, whereas the Tuctumpaya population was herbivorous. However, the percentage of plant material consumed in the El Simbral population was close to the critical value for herbivory-omnivory. We conclude that the three ecological aspects of L. etheridgei studied here are virtually identical in El Simbral and Tuctumpaya; therefore, this species is not affected significantly by the current fragmentation of forest.

Correspondence between thermal biology and locomotor performance in a liolaemid lizard from the southeastern coastal Pampas of Argentina.

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.

Latitudinal pattern of the thermal sensitivity of running speed in the endemic lizard Liolaemus multimaculatus.

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.

Integrating genetics, physiology and morphology to study desert adaptation in a lizard species.

Integration of multiple approaches is key to understand the evolutionary processes of local adaptation and speciation. Reptiles have successfully colonized desert environments, that is, extreme and arid conditions that constitute a strong selective pressure on organisms. Here, we studied genomic, physiological and morphological variations of the lizard Liolaemus fuscus to detect adaptations to the Atacama Desert. By comparing populations of L. fuscus inhabiting the Atacama Desert with populations from the Mediterranean forests from central Chile, we aimed at characterizing features related to desert adaptation. We combined ddRAD sequencing with physiological (evaporative water loss, metabolic rate and selected temperature) and morphological (linear and geometric morphometrics) measurements. We integrated the genomic and phenotypic data using redundancy analyses. Results showed strong genetic divergence, along with a high number of fixed loci between desert and forest populations. Analyses detected 110 fixed and 30 outlier loci located within genes, from which 43 were in coding regions, and 12 presented non-synonymous mutations. The candidate genes were associated with cellular membrane and development. Desert lizards presented lower evaporative water loss than those from the forest. Morphological data showed that desert lizards had smaller body size, different allometry, larger eyeballs and more dorsoventrally compressed heads. Our results suggest incipient speciation between desert and forest populations. The adaptive signal must be cautiously interpreted since genetic drift could also contribute to the divergence pattern. Nonetheless, we propose water and resource availability, and changes in habitat structure, as the most relevant challenges for desert reptiles. This study provides insights of the mechanisms that allow speciation as well as desert adaptation in reptiles at multiple levels, and highlights the benefit of integrating independent evidence.

Structure and comparative analysis of the mitochondrial genomes of Liolaemus lizards with different modes of reproduction and ploidy levels.

Liolaemus is the most specious genus of the Squamata lizards in South America, presenting exceptional evolutionary radiation and speciation patterns. This recent diversification complicates the formal taxonomic treatment and the phylogenetic analyses of this group, causing relationships among species to remain controversial. Here we used Next-Generation Sequencing to do a comparative analysis of the structure and organization of the complete mitochondrial genomes of three differently related species of Liolaemus and with different reproductive strategies and ploidy levels. The annotated mitochondrial genomes of ca. 17 kb are the first for the Liolaemidae family. Despite the high levels of sequence similarity among the three mitochondrial genomes over most of their lengths, the comparative analyses revealed variations at the stop codons of the protein coding genes and the structure of the tRNAs among species. The presence of a non-canonical dihydrouridine loop is a novelty for the pleurodonts iguanians. But the highest level of variability was observed in two repetitive sequences of the control region, which were responsible for most of the length heterogeneity of the mitochondrial genomes. These tandem repeats may be useful markers to analyze relationships of closely related species of Liolaemus and related genera and to conduct population and phylogenetic studies.

Decrease in preferred temperature in response to an immune challenge in lizards from cold environments in Patagonia, Argentina.

In ectotherms, the likelihood of surviving an infection is determined by the efficiency of thermoregulation, the availability of a variety of thermal microenvironments, the individual's health status, and the virulence of the infective agent. Physiological and behavioral demands related to an efficient immune response entail a series of costs that compete with other vital activities, specifically energy storage, growth, reproduction, and maintenance functions. Here, we characterize the thermal biology and health status by the presence of injuries, ectoparasites, body condition, and individual immune response capacity (using phytohemagglutinin in a skin-swelling assay) of the southernmost lizards of the world, Liolaemus sarmientoi, endemic to a sub-optimal, cold environment in Patagonia, Argentina. In particular, we study the effect of a bacterial endotoxin (lipopolysaccharide; LPS-treatment) on thermoregulation. We found that the field-active body temperature (Tb) was much lower than the preferred body temperature (Tp) obtained in the laboratory. All the individuals were in good body condition at the beginning of the experiments. The phytohemagglutinin test caused detectable thickening in sole-pads at 2 h and 24 h post-assay in males and non-pregnant females, indicating a significant innate immune response. In the experimental immune challenge, the individuals tended to prefer a low body temperature after LPS-treatment (2 h post-injection) and developed hypothermia, while the control individuals injected with phosphate buffered saline (PBS), maintained their body temperature throughout the trial. In both the LPS-treatment and PBS-control individuals, BC declined during the experiment. Hypothermia may allow this southernmost species to optimize the use of their energetic resources and reduce the costs of thermoregulation in a cold-temperate environment where they rarely attain the mean Tp (35.16 °C) obtained in laboratory.

Dieta de la lagartija neotropical Liolaemus polystictus(Squamata: Liolaemidae) de los andes centrales,Huancavelica, Perú / Diet of the neotropical lizard Liolaemus polystictus (Squamata:Liolaemidae) from the central Andes, Huancavelica, Peru

Resumen En este estudio se investigó la dieta de la lagartija neotropical Liolaemus polystictus en la región Huancavelica en los Andes centrales del Perú. Los ítems de la dieta fueron identificados en los contenidos estomacales de 54 muestras. El porcentaje de contenido volumétrico vegetal fue mayor al animal (V% contenido animal= 22.97 y V% contenido vegetal= 77.03), siendo el contenido animal representado por los artrópodos y con diez ítems alimentarios. Considerando solo el contenido animal, los coleópteros fueron los más representativos (N%= 32.05, FO=59.26 y V%= 41.36). Ninguna categoría animal mostró valores de IRI altos para ser considerados fundamentales, asimismo la selección de presas no mostro diferencias significativas entre machos, hembras y juveniles, ni entre los contenidos volumétricos vegetales entre adultos y juveniles, pero sí en los contenidos volumétricos vegetales entre machos y hembras. Se encontraron diferencias significativas entre la longitud, ancho y volumen de la presa y el ancho de la cabeza (AC) en machos de L. polystictus. Finalmente, proponemos la categoría de herbívoro para la especie L. polystictus, lo cual elevaría a ocho las especies del grupo L. montanus que se alimentan principalmente de vegetación.

Abstract This study assessed the diet of the Neotropical lizard Liolaemus polystictus from Huancavelica region in the Peruvian central Andes. The diet composition was identified from 54 sample stomach contents. Percentage of vegetable content was higher than the animal one (V% animal content= 22.97 and V% vegetable content= 77.03), and arthropods were the highest animal content with ten foods items. Within the animal content, Coleoptera were the most representative (N%= 32.05, FO= 59.26 and V%= 41.36%). No animal category showed high IRI values to be considered fundamental. There were not significant differences on prey selection between males, females and juveniles, and on vegetal volumetric contents between adults and juveniles. However, vegetal volumetric contents were significantly different between males and females. Significant differences were found between prey length, width and volume and L. polystictus male head width (AC). Finally, we pro-pose L. polystictus to be considered an herbivorous species, which bring to eight the number of species in the L. montanus group that feed mainly on vegetation.

Study of lipid reserves in Liolaemus koslowskyi (Squamata: Liolaemidae): reproductive and ecological implications.

In reptiles, many lipid reserve structures were recognized, and different patterns of storage and utilization of lipids have been identified. In this study, a population of Liolaemus koslowskyi was studied to analyze the diversity and functioning of the lipid reserve structures. The specific objectives were to identify the main lipid reserve structures, and to describe their seasonal patterns; to study sexual and seasonal variations of the reserve structures; and to analyze the relation between seasonal patterns of such reserves with the sexual cycle and other biological aspects. Individuals of both sexes collected at five different times of the year were analyzed. The abdominal fat bodies, livers, tails, fat deposits of the lateral folds of the neck, the fat bodies of the axillary region and gonads were weighted. The fat content of livers, tails and neck fat reserves were determined through the extraction in a Soxhlet device. The volume of the ovaries, oviductal oocytes and testicles, and the average surface and thickness of the epididymides were estimated. The abdominal fat bodies and the tail-extracted fats were the main lipid reserves. In general, females showed higher lipid contents, and significant seasonal variations in weight and lipid content in both sex were found, while seasonal variations in the liver fresh weight and liver fat content were found only in males. The axillar and neck fats deposits probably function as auxiliary reserves, and the caudal autotomy did not significantly affect tail fat content. The sexual cycles were synchronic in both sexes.

How mountains shape biodiversity: The role of the Andes in biogeography, diversification, and reproductive biology in South America's most species-rich lizard radiation (Squamata: Liolaemidae).

Testing hypotheses on drivers of clade evolution and trait diversification provides insight into many aspects of evolutionary biology. Often, studies investigate only intrinsic biological properties of organisms as the causes of diversity, however, extrinsic properties of a clade's environment, particularly geological history, may also offer compelling explanations. The Andes are a young mountain chain known to have shaped many aspects of climate and diversity of South America. The Liolaemidae are a radiation of South American reptiles with over 300 species found across most biomes and with similar numbers of egg-laying and live-bearing species. Using the most complete dated phylogeny of the family, we tested the role of Andean uplift in biogeography, diversification patterns, and parity mode of the Liolaemidae. We find that the Andes promoted lineage diversification and acted as a species pump into surrounding biomes. We also find strong support for the role of Andean uplift in boosting the species diversity of these lizards via allopatric fragmentation. Finally, we find repeated shifts in parity mode associated with changing thermal niches, with live-bearing favored in cold climates and egg-laying favored in warm climates. Importantly, we find evidence for possible reversals to oviparity, an evolutionary transition believed to be extremely rare.

Effect of temperature on the locomotor performance of species in a lizard assemblage in the Puna region of Argentina.

Locomotion is relevant to the ecology of reptiles because of its presumed influence on an organism's Darwinian fitness. Moreover, in ectothermic species, physiological performance capacity is affected by body temperature. We analyzed two components of locomotor performance in three species of lizards, Phymaturus extrilidus, Liolaemus parvus, and Liolaemus ruibali, in the Puna environment of Argentina. First, we estimated the thermal sensitivity of locomotion by measuring sprint speed at four different body temperatures. We included two measures of sprint speed: initial velocity and long sprint for sustained runs. Based on these data, we calculated the optimal temperature for performance and the optimal performance breadth. We also estimated endurance capacity at a single temperature. Maximum sprint speed for L. parvus was greater than L. ruibali and P. extrilidus in both initial velocity and long sprint. In contrast, L. parvus exhibited lower levels of endurance than L. ruibali and P. extrilidus. However, endurance in L. ruibali exceeded that of P. extrilidus. The species differed in the optimal temperature for the initial velocity with the lowest for L. ruibali (31.8 °C) followed by P. extrilidus (33.25 °C) and then L. parvus (36.25 °C). The optimal temperature for long sprint varied between 32 and 36 °C for all species. We found that all species attained maximum performance at body temperatures commonly experienced during daily activity, which was higher than the thermal quality of the environment. We found evidence for thermal sensitivity in locomotor performance in these species. However, we also show that the broad thermal breadth of performance suggests that the lizards are capable of sustaining near optimal levels of locomotor performance at ambient temperatures that would appear to be suboptimal. Thus, this lizard assemblage is capable of coping with the highly variable climatic conditions in the Puna region of Argentina.

Molecular evidence for conspecificity of two desert Liolaemus lizards (Iguania: Liolaemidae).

Liolaemus audituvelatus (Núñez Yáñez 1983) and L. manueli (Núñez, Navarro, Garín, Pincheira-Donoso Meriggio 2003) are endemic species of the Atacama Desert of northern Chile that belong to the montanus group. Both species are considered cryptic from each other and can only be distinguished by their distribution ranges and karyotypes. Originally, there was a wide separation zone between their known distribution ranges, but later collections reduced the gap from 430 km to only 150 km. In this study, we review the geographic information about both species and report new localities within the distribution gap, where species identification becomes difficult. We performed a molecular phylogenetic analysis and applied several species delimitation methods to reassess the taxonomic status of both nominal species and new intermediate populations. Our analyses support the placement of L. manueli in the synonymy of L. audituvelatus. We discuss the biogeographic and conservation implications of this new synonymy.

Hybridization could be a common phenomenon within the highly diverse lizard genus Liolaemus.

Hybridization is likely to occur more often between closely related taxa that have had insufficient time to diverge to the point of reproductive incompatibility; hybridization between deeply divergent lineages is rare. In squamate reptiles, hybridization has been proposed as a possible explanation for the extensive paraphyly observed in mitochondrial gene trees in several species complexes of the South American lizard genus Liolaemus. One of the best-documented cases is within the L. boulengeri and L. rothi complexes, which diverged ~5.5 million years ago. Here, we describe a comprehensive study for approaching the hybridization hypothesis between these lizard species complexes. We explored the level of gene tree discordance using the novel 'extra lineage contribution' statistics (XLC, presented in this study) that quantifies the level of gene tree discordance contribution per individual within a species. We included molecular data (12 nuclear and two mitochondrial genes) from 127 individuals, and results of a coalescent model-based analysis show that the most likely explanation for the gene tree-species tree discordance is interspecific hybridization. Our best-supported hypothesis suggests current and past hybridization between L. rothi (rothi complex) and L. tehuelche (boulengeri complex), and independently between L. rothi and L. boulengeri and L. telsen (boulengeri complex). The hybrid descendants are characterized by intermediate phenotypes between the parental species, but are more similar to L. rothi in body size. We discuss the possible role of hybridization in Liolaemus evolution.

Phylogeny, time divergence, and historical biogeography of the South American Liolaemus alticolor-bibronii group (Iguania: Liolaemidae).

The genus Liolaemus comprises more than 260 species and can be divided in two subgenera: Eulaemus and Liolaemus sensu stricto. In this paper, we present a phylogenetic analysis, divergence times, and ancestral distribution ranges of the Liolaemus alticolor-bibronii group (Liolaemus sensu stricto subgenus). We inferred a total evidence phylogeny combining molecular (Cytb and 12S genes) and morphological characters using Maximum Parsimony and Bayesian Inference. Divergence times were calculated using Bayesian MCMC with an uncorrelated lognormal distributed relaxed clock, calibrated with a fossil record. Ancestral ranges were estimated using the Dispersal-Extinction-Cladogenesis (DEC-Lagrange). Effects of some a priori parameters of DEC were also tested. Distribution ranged from central Perú to southern Argentina, including areas at sea level up to the high Andes. The L. alticolor-bibronii group was recovered as monophyletic, formed by two clades: L. walkeri and L. gracilis, the latter can be split in two groups. Additionally, many species candidates were recognized. We estimate that the L. alticolor-bibronii group diversified 14.5 Myr ago, during the Middle Miocene. Our results suggest that the ancestor of the Liolaemus alticolor-bibronii group was distributed in a wide area including Patagonia and Puna highlands. The speciation pattern follows the South-North Diversification Hypothesis, following the Andean uplift.

The True Identity of the New World Iguanid Lizard Liolaemus chillanensis Müller and Hellmich 1932 (Iguania: Liolaemidae) and Description of a New Species in the Liolaemus elongatus Group.

Jaime Troncoso-Palacios, Damien Esquerré, Félix A. Urra, Hugo A. Díaz, Carlos Castro-Pastene, and María Soledad Ruiz (2018) Liolaemus is a particularly species-rich radiation of New World iguanid lizards from southern South America. Thanks to intense systematic and taxonomic research, the knowledge on its species- level diversity has increased rapidly over the past several years. The L. elongatus species-complex has received considerable attention and a remarkable case is Liolaemus chillanensis, a name that has been used for two different species that are sympatric in Termas de Chillán, central Chile. Since the holotype is lost, we propose that the first step to identify the true L. chillanensis is through the analysis of the original description. Then we provide a morphological and molecular characterization of L. chillanensis based on topotypes and a description of the taxon previously confused with it.

Thermal physiology of three sympatric and syntopic Liolaemidae lizards in cold and arid environments of Patagonia (Argentina).

The thermal physiology determines the whole biology of ectotherm organisms, by limiting their acquisition and allocation of resources. Herein, we aim to add knowledge on how different species use the thermal resources when they coexist in a habitat, studying the thermal physiology of three sympatric and syntopic liolaemid lizards, Phymaturus querque, Phymaturus zapalensis, and Liolaemus elongatus during the summer season. We measured the body temperatures at capture places, the operative microenvironmental temperatures in the field, and the preferred body temperature in an experimental thermal gradient in the laboratory. We found that the three species are thermoregulators, selecting cooler thermal microenvironments than the ones expected by chance, and even cooler than the temperatures they selected in a laboratory environment. Liolaemus elongatus is a more efficient thermoregulator (E = 0.671) than the two Phymaturus species, P. querque (E = 0.441) and P. zapalensis (E = 0.471), which are moderate thermoregulators and, apparently, specialists in finding specific types of shelters, since they seem to select certain types of rock crevices. Herein, we found that during the summer season, although individuals have access to warm microenvironments, they spend time on cool refuges, probably to prevent overheating. This highlights the importance of an adequate spatial distribution of operative temperatures (T e), more than just a mere availability of appropriate temperatures.