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Despite the extensive study of various aspects of the genus Liolaemus, there remains a scarcity of information regarding the osteology of species. In the last two decades, over 100 species have been described within the genus, but still less than 10% of the Liolaemus species includes any osteological data. In this study, we provide a description of the skull of Liolaemus huayra, a taxon closely related to the L. dorbignyi clade (a subset of the L. montanus group). The species was originally described in 2008 based on a few specimens from the Sierra de Quilmes, Tucumán. By obtaining new specimens from a nearby locality (La Ovejería, Catamarca), we were able to prepare the skulls of two males and two females specimens. Despite the limited sample size, we observed intra-specific variability in characters such as postorbital and nasal shape, as well as mandibular curvature. We also document some inter-specific differences based on the scarce osteological information available from other species within the genus. This description constitutes a significant contribution to the osteology of the Liolaemidae clade. We emphasize the importance of detailed descriptions that provide morphological characters suitable for inclusion in comprehensive phylogenetic analyses., (© 2024 American Association for Anatomy.)

Few studies considered the anatomy of the nerve plexuses and musculature associated with them in ectothermic sauropsids. Based on differentiated Sudan Black B staining and conventional dissections, we describe the neuroanatomy of the brachial plexus, its main associated nerves, and muscles. For that, representatives of the genera Diplolaemus, Liolaemus, Phymaturus, and Tropidurus were selected. Based on this, potentially useful characters for phylogenetic analysis were described. Our results show that the brachial plexus can be formed by four, five, or six nerve branches. The brachial flexor trunk, circumflex, interosseous, median, radial, subscapulocoracoid, supracoracoid, and ulnar nerves were identified. Regarding the muscles innervated by the main nerves, the following muscles were identified: biceps brachii, deltoideus scapularis, latissimus dorsi, levator scapulae, pectoralis, serratus thoracis, trapezius, triceps longus caudalis, and triceps longus lateralis. Phylogenetic analyzes revealed 31 potential synapomorphies. There exists evidence that neuroanatomy studies in a phylogenetic context could provide useful information helping to elucidate the relationships between taxonomic groups., (© 2023 Wiley Periodicals LLC.)

Ecophysiological plasticity determines, to a great extent, the geographic distribution and the vulnerability of ectotherms to climate change. We studied the relationship between locomotor performance and temperature of Liolaemus elongatus lizards in three populations in northern Patagonia, Argentina, differing in thermal characteristics. We related the thermophysiological and locomotor performance parameters with the environmental conditions currently experienced by these populations and analyzed whether the expected increment of the environmental temperature due to climate change could affect these vital traits. We also determined, for one of the populations, the effects of 30 acclimation days at two temperature treatments (22°C and 30°C) on running speed, thermal preference in the laboratory (T pref ), panting threshold, and minimum critical temperature. We found that L. elongatus, despite the differences in environmental temperatures among the three sites, exhibited maximum speed at similar temperatures (optimum temperature for locomotor performance; T o ). The southern populations currently experience temperatures below that required to reach their maximum locomotor performance while the northernmost population is threatened by peaks of high temperatures that exceed the T o . Therefore, global warming could diminish lizards' running performance in northern populations and lizards may spend more time refuging and less time on other activities such as feeding, territory defense, and dispersion. However, we show evidence of plasticity in L. elongatus locomotor performance when acclimated at high temperatures resulting in a potential advantage to cushion the effect of the rising environmental temperatures expected during climate change., (© 2023 Wiley Periodicals LLC.)

Testosterone, the primary sex hormone in male lizards, is closely linked to Leydig cell activity (the cells where steroidogenesis occurs) throughout the reproductive cycle, but testosterone action is related to androgen receptors (ARs) distribution in the seminiferous epithelium. In temperate zones, environmental factors detected through the hypothalamic-pituitary-gonadal axis, downregulate plasma testosterone, resulting in a seasonal reproductive cycle. The aim of this work is to study plasma testosterone in adult male lizards of Liolaemus cuyanus, an oviparous species, throughout its reproductive cycle and its relationship with Leydig cell histology, TotalLeydigCell/ActiveLeydigCell (TLC/ALC) ratio, environmental factors (temperature, relative humidity and solar irradiation) and ARs distribution in seminiferous epithelium. Specimens (N = 27) were captured (October to March) in a semi-arid zone (Valle de Matagusanos, San Juan, Argentina) and grouped into three relevant reproductive periods: pre-reproductive (PrR), reproductive (R), and post-reproductive (PsR). Significant differences in plasma testosterone were found among these periods, highest during R than in PsR. A significant positive correlation between plasma testosterone and TLC/ALC ratio was also observed. Plasma testosterone has a significant positive correlation only with solar irradiation, but not with the other variables. In PrR and R, ARs distribution was cytoplasmic and nuclear, shifting to only cytoplasmic in PsR. These results highlight the close correspondence between plasma testosterone, Leydig cell histology and activity, environmental factors, and ARs distribution, resulting in a synchronization that allows males of L. cuyanus to coordinate their reproductive cycle with the most favorable environmental conditions, probably for mating and birth of offspring., (© 2024 Wiley Periodicals LLC.)

The diversity of habitats generated by the Andes uplift resulted a mosaic of heterogeneous environments in South America for species to evolve a variety of ecological and physiological specializations. Species in the lizard family Liolaemidae occupy a myriad of habitats in the Andes. Here, we analyze the tempo and mode of evolution in the thermal biology of liolaemids. We assessed whether there is evidence of local adaptation (lability) or conservatism (stasis) in thermal traits. We tested the hypothesis that abiotic factors (e.g., geography, climate) rather than intrinsic factors (egg-laying [oviparous] or live-bearing [viviparous], substrate affinity) explain variation in field active body temperature (T b ), preferred temperature (T p ), hours of restriction of activity, and potential hours of activity. Although most traits exhibited high phylogenetic signal, we found variation in thermal biology was shaped by geography, climate, and ecological diversity. Ancestral character reconstruction showed shifts in T b tracked environmental change in the past ∼20,000 years. Thermal preference is 3°C higher than T b , yet exhibited a lower rate of evolution than T b and air temperature. Viviparous Liolaemus have lower T b s than oviparous species, whereas T p is high for both modes of reproduction, a key difference that results in a thermal buffer for viviparous species to cope with global warming. The rapid increase in environmental temperatures expected in the next 50-80 years in combination with anthropogenic loss of habitats are projected to cause extirpations and extinctions in oviparous species., (© 2021 The Authors. Evolution © 2021 The Society for the Study of Evolution.)

The thermal quality of the habitat is key for the regulation of body temperature in terrestrial ectotherms and, therefore, permits them to carry out their fundamental biological activities. In thermally heterogeneous environments, ectotherms might follow different behavioral or physiological strategies to maintain their body temperature within biologically adequate boundaries, for which they depend on microhabitat selection. These aspects are, thus, relevant in the context of habitat degradation and land-use change. In this study, we characterized the thermal ecology of three lizard species (genus Xantusia) that differ in microhabitat use along the Baja California peninsula, Mexico. We made three predictions: (1) the three species will follow different thermoregulatory strategies according to habitat thermal quality; (2) the thermal requirements and tolerances of these species will match the environmental or microenvironmental thermal conditions; and (3) due to their habitat and range restriction, the species studied will be highly vulnerable to climate change. Our results indicate the existence of thermoregulatory mechanisms in Xantusia to face thermal heterogeneity, including behavioral thermoregulation by choosing different microhabitats, shifts in activity periods, and adaptation to particular high thermal quality microhabitats. Furthermore, despite their association to specific microhabitats and specialized physiology, the studied species will not be adversely affected by climate change, as the increased microenvironmental temperatures will lead to a higher habitat thermal quality and lower costs of thermoregulation. However, we do not discard other indirect adverse effects of climate change not considered in this study., (© 2021 Wiley Periodicals LLC.)

We redescribe Liolaemus bibronii and describe three new species of Liolaemus , a genus of lizards distributed across South America. These species belong to the L. alticolor – bibronii group, which are included in the subgenus Liolaemus s.s. Liolaemus bibronii was previously proposed as a species complex, but many populations initially assigned to this complex were described as valid species. The three new species described here were populations denominated under L. bibronii. In order to validate the new species, we apply an integrative approach, including molecular and morphological evidence. Also, we perform phylogenetic analyses applying parsimony and Bayesian inference. The three new species described here show a set of character states that allow them to be distinguished from L. bibronii , from each other and from all other species of Liolaemus. Our phylogenies show that the newly described species are more related to other species than to L. bibronii. With this study, we are closer to solving the taxonomic puzzle that L. bibronii represents. [ABSTRACT FROM AUTHOR]

Evolution proceeds unevenly across the tree of life, with some lineages accumulating diversity more rapidly than others. Explaining this disparity is challenging as similar evolutionary triggers often do not result in analogous shifts across the tree, and similar shifts may reflect different evolutionary triggers. We used a combination of approaches to directly consider such context-dependency and untangle the complex network of processes that shape macroevolutionary dynamics, focusing on Pleurodonta, a diverse radiation of lizards. Our approach shows that some lineage-wide signatures are lost when conditioned on sublineages: while viviparity appears to accelerate diversification, its effect size is overestimated by its association with the Andean mountains. Conversely, some signals that erode at broader phylogenetic scales emerge at shallower ones. Mountains, in general, do not affect speciation rates; rather, the occurrence in the Andean mountains specifically promotes diversification. Likewise, the evolution of larger sizes catalyzes diversification rates, but only within certain ecological and geographical settings. We caution that conventional methods of fitting models to entire trees may mistakenly assign diversification heterogeneity to specific factors despite evidence against their plausibility. Our study takes a significant stride toward disentangling confounding factors and identifying plausible sources of ecological opportunities in the diversification of large evolutionary radiations. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos de Herpetología is the property of Asociacion Herpetologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The diversification of lineages is facilitated or constrained by the simultaneous evolution of multiple components of the phenotype that interact with each other during the course of speciation. When evolutionary radiations are adaptive, lineages proliferate via the emergence of multiple phenotypic optima that underlie diversification of species across multiple ecological niches. When radiations are non-adaptive, lineage proliferation unfolds constrained by similar (or nearly identical) correlations among traits that keep phenotypic and ecological diversity across newly emerging species within a single optimum. Nature offers very few opportunities where both types of diversification occur between closely related and highly diverse lineages. The Liolaemidae family of South American lizards offers unique such opportunities given two speciose lineages that have rapidly proliferated via adaptive (Liolaemus) and non-adaptive (Phymaturus) radiations. We analyze body shape in lizards in association with type of diet (herbivory, omnivory or carnivory). In these lizards, diet types have been suggested to be linked to body size. Our results confirm this hypothesis, with three body size optima tightly linked to all three diet types when radiation is both adaptive and non-adaptive. Diet reconstruction along their evolutionary history showed that the commonancestor of Liolaemidae was likely omnivorous, which is matched by ancestral reconstruction of body size. Phylogenetic PCA revealed that herbivorous species generally have more differentiated body shape than insectivores and omnivores. Herbivorous species have evolved larger heads, shorter hindlimbs and a small difference between forelimb and hindlimb length. In contrast, omnivores and insectivores have smaller heads and longer hindlimbs. Collectively, trophic niche plays an important role in defining body shape and size across species within lineages, and the patterns of trait-ecology correlations remain consistent when lineages have diversified via adaptive and non-adaptive radiation. [ABSTRACT FROM AUTHOR]

Only since the late 1980s have lizard specialists begun incorporating phylogenetic information to the classification of leiosaurids. These are among the most enigmatic South American lizards, with 35 currently recognised species arranged in six genera. To evaluate their relationships, we assembled a data set based on published and novel information containing 135 morphological characters and 11,235 DNA base pairs (14 loci) for up to 52 terminals, including outgroups. We performed 13 analyses based on different optimality criteria (parsimony, maximum likelihood, and coalescent approach) and indel coding strategies (gaps coded as missing data or as a fifth state). We also evaluated the impact of phenotypic evidence on the phylogeny of leiosaurids, and investigated the level of informativeness and potential sources of topological conflict using a Quartet Sampling analysis. Phylogenetic analyses supported the monophyly of major leiosaurid clades, including subfamilies Enyaliinae and Leiosaurinae, and the 'para-anoles' clade (Urostrophus + Anisolepis). However, Urostrophus was inferred as paraphyletic, with U. vautieri forming a clade with Anisolepis. These relationships motivate the synonymization of Anisolepis Boulenger, 1885 with Urostrophus Duméril & Bibron, 1837. The monophyly of Pristidactylus and, surprisingly, of Enyalius, were also challenged, underscoring the need for additional phylogenetic work. Finally, we described Urostrophus chungarae sp. nov. from the Torotoro National Park, Potosí, Bolivia. This apparently rare leiosaurid was inferred as sister to U. gallardoi, a Chacoan species distributed in northern Argentina and southeastern Bolivia. We conclude with a revised classification of Leiosauridae and by pointing out a number of unresolved issues that require further systematic investigation. [ABSTRACT FROM AUTHOR]

Ectotherms thermoregulate to maintain their body temperature within the optimal range needed for performing vital functions. The effect of climate change on lizards has been studied as regards the sensitivity of locomotor performance to environmental temperatures. We studied thermoregulatory efficiency and locomotor performance for Liolaemus fitzgeraldi in the Central Andes of Argentina. We determined body temperature, micro‐environmental temperatures and operative temperatures in the field. In the laboratory, we measured preferred temperatures and calculated the index of thermoregulatory efficiency. We estimated the thermal sensitivity of locomotion by measuring sprint speed (initial velocity and long sprint) and endurance at five different body temperatures. Body temperature was not associated with either micro‐environmental temperature, nor did it show differences with preferred temperatures. Thermoregulatory efficiency was moderate (0.61). Initial velocity and long sprint trials showed differences at different temperatures; however, endurance did not. Moreover, the optimal temperatures for the performance trials showed no significant differences among themselves. We conclude that Liolaemus fitzgeraldi has thermal sensitivity in locomotor performance with respect to body temperature and that it is an eurythermic lizard that experiences a large variation in body temperature and that has thermal flexibility in the cold. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos de Herpetología is the property of Asociacion Herpetologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The evolution of body size within and among species is predicted to be influenced by multifarious environmental factors. However, the specific drivers of body size variation have remained difficult to understand because of the wide range of proximate factors that covary with ectotherm body sizes across populations with varying local environmental conditions. Here, we used female Eremias argus lizards collected from different populations across their wide range in China, and constructed linear mixed models to assess how climatic conditions and/or available resources at different altitudes shape the geographical patterns of lizard body size across altitude. Lizard populations showed significant differences in body size across altitudes. Furthermore, we found that climatic and seasonal changes along the altitudinal gradient also explained variations in body size among populations. Specifically, body size decreased with colder and drier environmental conditions at high altitudes, reversing Bergmann's rule. Limited resources at high altitudes, measured by the low vegetative index, may also constrain body size. Therefore, our study demonstrates that multifarious environmental factors could strongly influence the intraspecific variation in organisms' body size. [ABSTRACT FROM AUTHOR]

Substrate properties can affect the thermal balance of organisms, and the colored integument, alongside other factors, may influence heat transfer via differential absorption and reflection. Dark coloration may lead to higher heat absorption and could be advantageous when substrates are cool (and vice versa for bright coloration), but these effects are rarely investigated. Here, we examined the effect of substrate reflectance, specific heat capacity (cp), and body size on the dorso-ventral brightness using 276 samples from 12 species of cordylid lizards distributed across 26 sites in South Africa. We predicted, and found, that bright ventral colors occur more frequently in low cp (i.e. drier, with little energy needed for temperature change) substrates, especially in larger body-sized individuals, possibly to better modulate heat transfer with the surrounding environment. By contrast, dorsal brightness was not associated with body size nor any substrate thermal property, suggesting selection pressures other than thermoregulation. Ancestral estimation and evolutionary rate analyses suggest that ventral brightness rapidly differentiated within the Cordylinae starting 25 Mya, coinciding with an aridification period, further hinting at a thermoregulatory role for ventral colors. Our study indicates that substrate properties can have a direct role in shaping the evolution of ventral brightness in ectotherms. [ABSTRACT FROM AUTHOR]

Animal personality can be defined as behavioral individual consistency across contexts and time, and sociability may facilitate it. Boldness and exploration can be considered as social conflictive behaviors and in lizards, social scent can either diminish or promote social conflicts. We studied boldness and exploration in Liolaemus albiceps Lobo and Laurent, 1995 and Liolaemus coeruleus Cei and Ortiz, 1983, and tested whether Liolaemus albiceps, a lesser aggressive species, presents higher individual consistency in a socially nonconflictive behavior, such as escape (boldness). We also expect Liolaemus coeruleus, a more aggressive species, to present higher individual consistency in exploration, which is socially more conflictive behavior. We exposed lizards to their own conspecifics and control scent treatments. We calculated the repeatability for boldness and exploration, analyzed their correlation, and tested for behavioral plasticity. Boldness and exploration were repeatable in Liolaemus albiceps at species level, with females showing highly repeatable boldness, and males, highly repeatable exploration. Liolaemus coeruleus exhibited no significant repeatability for either behavior. There was no correlation between these two behaviors, and both species showed plasticity. Liolaemus albiceps individuals were bolder and explored less under conspecific scents. Liolaemus coeruleus individuals explored less in presence of their own scents than novelty scents, and presented interindividual variation in plasticity. A peaceful lifestyle may favor behavioral consistency within individuals, whereas a more aggressive lifestyle may constrain within and among individual consistency in a chemical communication context. However, individual differences in plasticity could counterbalance this constraint. [ABSTRACT FROM AUTHOR]

Bite force is important in understanding how feeding biomechanics impacts the life‐history of vertebrates. Bite force has been measured in many lizards and crocodilians but fewer turtles and snakes. Few comparative interspecific studies exist of the inter‐relationships between body size, jaw musculature and bite force. This study collated data reported in the literature for bite force and mass of the jaw musculature in reptiles and explored the relationships between these variables and body mass and size. Two hypotheses were explored: (1) bite force and mass of the jaw musculature scale with body size irrespective of order (as a broad taxonomic grouping) when controlled for phylogeny, and (2) bite force and jaw musculature mass would be directly related and be unrelated to order. Phylogenetically controlled Bayesian analyses showed that in relation to body mass there were different relationships with bite force for testudines compared to saurians and crocodilians. For snout–vent length, squamates and crocodilians exhibited a single relationship, but for head length, all reptile orders exhibited different allometric patterns. Although there was a strong phylogenetic signal in all cases, indicating that there are clusters of closely related species for a measure of size, there was no effect of order on the relationships between measures of body size and mass of the jaw musculature. The relationship between bite force and jaw muscle mass was isometric and did not differ among reptile orders. Several ecological factors may correlate with head morphology and bite force in reptiles. Further studies could explore the evolutionary drivers that shape the relationship between head size, jaw musculature and bite force. Similarities for the relationships between bite force and body size in different reptilian orders suggests that this could be a model system to demonstrate fundamental biomechanical principles of how jaw muscles generate a bite force. [ABSTRACT FROM AUTHOR]

Evolutionary transitions in life‐history strategies, such as the shift from egg‐laying to live birth (viviparity) are of great interest to evolutionary biologists. In squamate reptiles, several hypotheses have been proposed to explain viviparity including the cold climate hypothesis, maternal manipulation hypothesis, hypoxia hypothesis, and several others. We used two approaches: first we studied 45 species of Liolaemus, a genus where nearly 50% of species are viviparous, using a diverse ecophysiological dataset to examine the cold climate and maternal manipulation hypotheses. We collected environmental thermal data (accounting for elevational differences among species), physiological traits including preferred body temperature and its coefficient of variation as an indicator of precision in thermoregulation. Additionally, we collected standard metabolic rates for 23 of the 45 species. In one clade (the darwinii group of species) with both reproductive modes, we ran our second approach. We tested for differences in thermal physiology and metabolic rates between viviparous and oviparous species during pregnancy and non‐pregnancy periods. The cold climate hypothesis received strong support because viviparous species occur in sites with colder air temperatures (including areas at both higher elevations and latitudes) compared with oviparous species. Our detailed analysis showed that the maternal manipulation hypothesis also is supported; pregnant viviparous females show lower variation in their selected temperature. Our evidence suggests that the Andean orogeny is likely to have played a key role in the diversification of Liolaemus lizards and the evolution of viviparity in this clade may have been driven by a variety of physiological advantages accrued at different stages of embryogenesis and over evolutionary time. Thus, historical climate changes may have led to egg retention and may have been accompanied by other adaptations such as thermoregulation precision. [ABSTRACT FROM AUTHOR]

The impact of climate change on global biodiversity is firmly established, but the differential effect of climate change on populations within the same species is rarely considered. In ectotherms, melanism (i.e. darker integument due to heavier deposition of melanin) can significantly influence thermoregulation, as dark individuals generally heat more and faster than bright ones. Therefore, darker ectotherms might be more susceptible to climate change.Using the colour‐polyphenic lizard Karusasaurus polyzonus (Squamata: Cordylidae), we hypothesized that, under future climatic projections, darker populations will decrease their activity time more than brighter ones due to their greater potential for overheating.To test this, we mechanistically modelled the body temperatures of 56 individuals from five differently coloured populations under present and future climate conditions. We first measured morphological traits and integumentary reflectance from live animals, and then collected physiological data from the literature. We used a biophysical model to compute activity time of individual lizards as proxy for their viability, and thereby predict how different populations will cope with future climate conditions.Contrary to our expectations, we found that all populations will increase activity time and, specifically, that darker populations will become relatively more active than bright ones. This suggests that darker populations of K. polyzonus may benefit from global warming.Our study emphasizes the importance of accounting for variation between populations when studying responses to climate change, as we must consider these variations to develop efficient and specific conservation strategies. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of American Naturalist is the property of University of Chicago and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nematodes are little known in the Argentine herpetofauna. In order to increase and contribute to the knowledge of parasitism in reptiles, we studied nematodes found in three species of lizards (Aurivela longicauda, Liolaemus darwinii, and L. riojanus) and one species of snake (Philodryas trilineata) from the Monte desert of center-west Argentina. We registered generalist nematodes commonly found in reptiles, belonging to three taxa: Physaloptera sp. (larvae), Physaloptera retusa (adults) (Physalopteridae) and Parapharyngodon riojensis (Pharyngodonidae) (adults). Liolaemus darwinii had the lowest prevalence of Physaloptera sp. (larvae) (30%) and a mean intensity of 1.3±0.4 (1-2). The lizard A. longicauda had the highest parasitic diversity (2 taxa) with prevalence (50%) and mean intensity (4±3.5) of Physaloptera retusa (adults), also with prevalence (12.5%) and mean intensity (20±0) of Parapharyngodon riojensis (adults). Due to the low number of studied specimens, precise conclusions cannot be drawn for Liolaemus riojanus (n = 2) and P. trilineata (n = 1). However, because the hosts were previously fixed, the results probably may do not represent real infection patterns. The four reptile species correspond to new host records from Argentina, and the information provided contributes to the knowledge of endoparasitism in reptiles of the Argentine Monte region. [ABSTRACT FROM AUTHOR]

Reproductive physiology is influenced by environmental pressures, particularly in ectothermic species living in harsh climatic conditions. Studying the period of time in which males exhibit semen availability and their sperm traits constitutes a powerful tool to evaluate the fertility potential of males because sperm size and sperm velocity have been proposed as determinants in fertilization success. Pristidactylus achalensis is a lizard endemic to the highest mountain areas in Central Argentina and shows a pattern of seasonal activity. Here, we study the period of time when males possess sperm during the active season and characterize the spermatozoa based on sperm morphometric and dynamic traits among males and within ejaculate. Males possess sperm in their ejaculates only during the spring months of the active season, suggesting that reproductive activity is restricted to this time. Spermatozoa of Pristidactylus achalensis show intra-specific variation in sperm traits among males and within ejaculate, suggesting different reproductive potential among males. Since this species only occupies the highest areas of the mountains and is categorized as vulnerable, basic information about reproduction and sperm physiology could be useful for potential population conservation strategies. [ABSTRACT FROM AUTHOR]

The genus Liolaemus includes 268 species, classified in two subgenera, Eulaemus and Liolaemus sensu stricto. The latter is formed by 12 monophyletic groups; one of them being the Liolaemus elongatus group, distributed in South America. We studied the biogeographic history of the L. elongatus group. We obtained a phylogenetic hypothesis recovering five main clades: the L. punmahuida, L. elongatus sensu stricto, L. kriegi, L. petrophilus and L. capillitas clades. Based on that hypothesis we obtained a time calibrated tree. The ancestral ranges were estimated applying three methodologies: DEC, DEC+j (using predefined areas) and GEM (using explicit geographical data). Our results show that the ancestral area of the L. elongatus group was located in central Argentina, and its divergence began around 11.5 Mya. From here, a combination of events (founder events and/or vicariances) led the species to their current distribution. Despite their differences, DEC+j and GEM show congruent results. [ABSTRACT FROM AUTHOR]

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Habitat use and thermal biology are closely related, because thermal microclimates vary spatially. The use of habitat and microhabitat by different species influences many of their traits, such as their physiology, and may, therefore exert a direct effect on survival. Ectothermal animals, such as lizards, are affected by thermal and biophysical environments they inhabit, and the particular use of a given substrate reflects an overlap between thermally adequate microhabitats, and behavioral preferences. By exploiting certain microhabitats and avoiding others, many lizards tend to maintain their body temperature within a range that allows maximum performance. Here, we evaluate how two syntopic species of lizards, Liolaemus pacha and L. ramirezae, use substrates with different exposure to solar radiation. Our hypothesis is that L. pacha uses both soil and rock substrates indistinctly, due to being a generalist species, whereas L. ramirezae uses the rock substrate more frequently, due to its saxicolous habits. We expect temperatures to be different both in substrates, and in different exposures, and thermal characteristics of each species to condition their use. For example, because the body temperature range of L. pacha is wider, we predict that substrate use will be wider. A pre-established 100x75 m area was monitored during four Austral springs and summers between 2011 and 2015, in Los Cardones, Amaicha del Valle, Tucumán, Argentina. Species ' substrate where the lizard was found (soil or rock), and exposure to solar radiation: sun, filtered shade or full shade was recorded. After capture, lizard body temperature (Tb), substrate temperature (Ts), and air temperature (Ta) were recorded in the place of the first observation of the lizard. Obtained results show that L. pacha and L. ramirezae had a more persistent use of the rock than the soil substrate, thus considering them saxicolous species. Further, they were frequently observed exposed to direct sunlight. Average body temperature was higher than environmental temperature (Ts and Ta), and significantly different in each exposure type (sun, filtered shade and full shade), and in both substrates (rock and soil). Differential use of substrate and the relationship between body temperature and microhabitat temperatures suggests that L. pacha and L. ramirezae are "active thermoregulators", using both substrate surfaces and solar radiation as heat sources. [ABSTRACT FROM AUTHOR]

Formerly Cnemidophorus was thought to be the most speciose genus of Teiidae. This genus comprised four morphological groups that were later defined as four different genera, Ameivula, Aurivela, Cnemidophorus and Contomastix. The last appears as paraphyletic in a recent phylogenetic reconstruction based on morphology, but monophyletic in a reconstruction using molecular characters. Six species are allocated to Contomastix. One of them, C. lacertoides, having an extensive and disjunct geographic distribution in Argentina, Uruguay and Brazil. Preliminary analyses revealed morphological differences among its populations, suggesting that it is actually a complex of species. Here, we describe a new species corresponding to the Argentinian populations hitherto regarded as C. lacertoides, by integrating morphological and molecular evidence. Furthermore, we demonstrate that the presence of notched proximal margin of the tongue is a character that defines the genus Contomastix. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos de Herpetología is the property of Asociacion Herpetologica Argentina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Phymaturus is a clade of lizards that occurs at moderate to high elevations in western Argentina and the adjacent central region of Chile, as well as in various volcanic plateaus of the Patagonian region of Argentina. This genus had previously been divided into two groups: the patagonicus and the palluma groups. In this study, we analyzed relationships within the patagonicus group. The data set was built for 23 species plus nine other terminal taxa of undetermined taxonomic status. In total, 10,631 bp (ND4, Cytb, 12S, COI, five protein coding nuclear genes and seven anonymous nuclear loci) and 254 morphological characters were analyzed in a combined data set for 35 ingroup taxa and nine outgroups. We also ran separate DNA sequence and morphological data sets. We identified four main clades, and revealed congruencies and incongruences with previous studies. The indistinctus clade is recovered as the most basal within the patagonicus group in the strict parsimony analysis, while the somuncurensis clade is the most basal under Bayesian inference. The previously recovered calcogaster clade resulted paraphyletic in both analyses and part of their species are included in a redefined somuncurensis clade. We found low support at basal nodes provoked in part by contradictory evidence shown by rogue taxa. We show the phylogenetic information given by each partition/marker and how they contribute to relationships found in the total evidence analysis. We discuss the phylogenetic position of Phymaturus manuelae, Phymaturus tenebrosus, and Phymaturus patagonicus. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Body temperatures in ectotherms are strongly affected by their thermal environment. Ectotherms respond to variation in the thermal environment either by modification of behavioural thermoregulation to maintain their optimal body temperature or by shifting their optimal body temperature. In this study, the body temperatures of males of three populations of spotted snow skinks, Niveoscincus ocellatus , living along an altitudinal gradient (low, mid, and high altitude) were studied in the field and laboratory in spring, summer, and autumn, representing the full activity period of this species. The environmental variation across both sites and seasons affected their field active body temperatures. At the low and mid altitude, N. ocellatus had a higher mean body temperature than at the high altitude. Animals achieved their thermal preference at the low and mid altitude sites in all seasons. At the high altitude, however, N. ocellatus struggled to reach its preferred body temperatures, especially in autumn. The lower body temperature at the high-altitude site is likely due to limited thermal opportunity and/or an effect of avoiding the costs associated with increased intensity of basking. This study investigated the body temperatures of spotted snow skinks living along an altitudinal gradient over a full activity period of this species. The environmental variation across sites and seasons affected their body temperatures, and they achieved their thermal preference with the exception at high altitude. Thermoregulatory behaviour acts as a potential buffer to overcome changes in environmental conditions. Photo by Erik Wapstra. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Herpetology is the property of Society for the Study of Amphibians & Reptiles and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

By analysing size and shape separately, geometric morphometric methods (GM) are a powerful tool to evaluate morphological differences within and between taxa. In this work, we used GM to investigate whether lizards of the Liolaemus melanops complex differ in shape and size. Specifically, we analysed head shape and size variation to quantify intraspecific sexual dimorphism and interspecific differences. We found sexual dimorphism in six of the seven investigated species (L. canqueli, L. dumerili, L. goetschi, L. martorii, L. melanops and L. morenoi). Five species (L. canqueli, L. casamiquelai, L. martorii, L. melanops and L. morenoi) were distinct in shape and size, whereas L. goetschi and L. dumerili were indiscernible from each other. This work illustrates the value of GM to study morphological variation in lizards, suggesting that similar studies would be valuable for testing species boundaries in other groups of Liolaemus. [ABSTRACT FROM AUTHOR]

The body temperature of ectotherms depends on the environmental temperatures and behavioral adjustments, but morphology may also have an effect. For example, in colder environments, animals tend to be larger and to show higher thermal inertia, as proposed by Bergmann's rule and the heat balance hypothesis (HBH). Additionally, dark coloration increases solar radiation absorption and should accelerate heat gain (thermal melanism hypothesis, TMH). We tested Bergmann's rule, the HBH and the TMH within the Liolaemus goetschi lizard clade, which shows variability in body size and melanic coloration. We measured heating and cooling rates of live and euthanized animals, and tested how morphology and color affect these rates. Live organisms showless variable and faster heating rates compared with cooling rates, suggesting behavioral and/or physiological adjustments. Our results support Bergmann's rule and the HBH, as larger species show slower heating and cooling rates. However, we did not find a clear pattern to support the TMH. The influence of dorsal melanism on heating by radiation was masked by the body size effect in live animals, and results from euthanized individuals also showed no clear effects of melanism on heating rates. Comparison among three groups of live individuals with different degrees of melanism did not clarify the influence of melanism on heating rates.However, when euthanized animals from the same three groups were compared, we observed that darker euthanized animals actually heat faster than lighter ones, favoring the TMH. Although unresolved aspects remain, body size and coloration influenced heat exchange, suggesting complex thermoregulatory strategies in these lizards, probably regulated through physiology and behavior, which may allow these small lizards to inhabit harsh weather environments. [ABSTRACT FROM AUTHOR]

For ectotherms like lizards, temperature plays a key role in shaping life history traits such as age and size at sexual maturity, longevity and growth. In cold, temperate habitats like Patagonia, balancing the energy expended to growth and reproduction is vital for persistence. In the present study, age and growth of the lizard Phymaturus spectabilis were studied using skeletochronology. We estimated individual ages, growth rates and life history parameters related to growth and reproduction. Juveniles were up to five years old. The youngest adult male was six years and the youngest adult female was seven years of age; females reached a higher longevity, and the oldest specimen was a female of 12 years. Resulting from the short activity season of Patagonia, P. spectabilis were characterised by delayed sexual maturity and medium longevity. Considering the rather short reproductive lifetime and small clutch size, P. spectabilis is characterised by the lowest net reproductive rate documented for liolaemids so far. This suggests that the capability to demographically recover from disturbances is low. [ABSTRACT FROM AUTHOR]

Lizards that live in the harsh climate of the Argentinean Patagonia (40°-53° S) are active for a period restricted to spring and summer when vitellogenesis, pregnancy and birth take place. Herein, we present data on the female reproductive cycle, body size at sexual maturity, litter size and fat-body cycle of one of the world's southernmost reptiles, Liolaemus sarmientoi. We also provide preliminary data on the reproductive cycle of a sympatric species, L. magellanicus. Females of both species start vitellogenesis in late spring, probably arrested or continued at very low rates during brumation resumed in the spring of the next year. Pregnancy starts in spring and births of L. sarmientoi (2 to 7 offspring) and L. magellanicus (3 to 4 offspring) occur over a month in midsummer. Females that give birth earlier can start a new vitellogenic cycle before autumn and perform an annual reproductive cycle. However, females which give birth later delay the start of a new vitellogenic cycle until the next spring, performing a biennial reproductive cycle. Thus, females have the potential to adjust their frequency of reproduction according to the energetic restrictions imposed by environmental conditions in the southernmost lands of South America. [ABSTRACT FROM AUTHOR]

Bite-force performance is an ecologically important measure of whole-organism performance that shapes dietary breadth and feeding strategies and, in some taxa, determines reproductive success. It also is a metric that is crucial to testing and evaluating biomechanical models. We reviewed nearly 100 published studies of a range of taxa that incorporate direct in vivo measurements of bite force. Problematically, methods of data collection and processing vary considerably among studies. In particular, there is little consensus on the appropriate substrate to use on the biting surface of force transducers. In addition, the bite out-lever, defined as the distance from the fulcrum (i.e. jaw joint) to the position along the jawline at which the jaws engage the transducer, is rarely taken into account. We examined the effect of bite substrate and bite out-lever on biteforce estimates in a diverse sample of lizards Results indicate that both variables have a significant impact on the accuracy of measurements. Maximum bite force is significantly greater using leather as the biting substrate compared with a metal substrate. Lessforceful bites on metal are likely due to inhibitory feedback from mechanoreceptors that prevent damage to the feeding apparatus. Standardization of bite out-lever affected which trial produced maximum performance for a given individual. Indeed, maximum bite force is usually underestimated without standardization because it is expected to be greatest at the minimum out-lever (i.e. back of the jaws), which in studies is rarely targeted with success. We assert that future studies should use a pliable substrate, such as leather, and use appropriate standardization for bite out-lever. [ABSTRACT FROM AUTHOR]

Lizard assemblages may experience resource partitioning in the spatial, trophic or temporal dimensions of their niche. Niche segregation does not always imply competition, and the role of interspecific competition is better understood when the response of species to the presence or absence of other species is evaluated. The aim of this study is to determine daily activity patterns and food consumption in two phylogenetically related species (Phymaturus roigorum and P. payuniae). These saxicolous and herbivorous species live in sympatry in the volcanic region of Payunia, in central-west Argentina. One of these species can also be found in allopatry, allowing comparative studies on their lifestyle. We evaluated the temporal daily patterns of both species and their diet overlap. Although competition is not evident between the species studied here, it is shown that selectivity towards different plant species and the time schedule of foraging are the primary mechanisms that promote the coexistence of these lizards. Daily basking activity, however, was similar in both species. [ABSTRACT FROM AUTHOR]

Estimating the effective geographical ranges of species is central to species-oriented conservation and management. In this paper, we review the geographical distribution of Liolaemus elongatus Koslowsky, 1896 with three new records for northern Chubut and southern Río Negro provinces, Argentina. Based on detailed locality records pooled from multiple data sources, including new records obtained for this study, we revise the range of L. elongatus sensu stricto and provide geographical distribution maps comparing the previously recognized range to that proposed herein. Our results show that L. elongatus possesses a much more limited geographic distribution than previously thought, being restricted to areas south of 38°S latitude; the newly proposed range is merely half the species formerly recognized geographical distribution. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Species delimitation is a major research focus in evolutionary biology because accurate species boundaries are a prerequisite for the study of speciation. New species delimitation methods (SDMs) can accommodate nonmonophyletic species and gene tree discordance as a result of incomplete lineage sorting via the coalescent model, but do not explicitly accommodate gene flow after divergence. Approximate Bayesian computation (ABC) can incorporate gene flow and estimate other relevant parameters of the speciation process while testing alternative species delimitation hypotheses. We evaluated the accuracy of BPP, SpeDeSTEM, and ABC for delimiting species using simulated data and applied these methods to empirical data from lizards of the Liolaemus darwinii complex. Overall, BPP was the most accurate, ABC showed an intermediate accuracy, and SpeDeSTEM was the least accurate under most simulated conditions. All three SDMs showed lower accuracy when speciation occurred despite gene flow, as found in previous studies, but ABC was the method with the smallest decrease in accuracy. All three SDMs consistently supported the distinctness of southern and northern lineages within L. darwinii. These SDMs based on genetic data should be complemented with novel SDMs based on morphological and ecological data to achieve truly integrative and statistically robust approaches to species discovery. [ABSTRACT FROM AUTHOR]

Tulli, M.J., Herrel, A., Vanhooydonck, B. and Abdala, V. 2012. Is phylogeny driving tendon length in lizards?- Acta Zoologica (Stockholm) 93: 319-329. Tendons transmit tensile forces generated by muscles and are a crucial part of the musculoskeletal system in vertebrates. Because tendons and tendon cells respond to altered mechanical load by increasing collagen synthesis, we hypothesized that a correlation between tendon morphology and the loading regime imposed by locomotor style or habitat use exists. This makes tendons an interesting model for studying the relationship between morphology and environment. In this study, we compare the general morphology of the palmar flexor plate, the length of the digital tendons, and the length of the flexor carpi ulnaris tendon in species of lizards that exploit a variety of structural habitats. The results from statistical analyses show that phylogenetic relatedness has a major impact on our ability to detect differences between habitat groups, and no differences in tendon length could be detected between iguanian species occupying different habitats when taking into account the relatedness between species. Our data for lizards diverge from the general mammalian paradigm where variation in tendon is often associated with habitat use or locomotor style. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Herpetology is the property of Society for the Study of Amphibians & Reptiles and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fecundity is a primary component of fitness. Theory predicts that the evolution of fecundity through increased brood size results from fecundity selection favouring larger female size to accommodate more offspring and to store more energy. This is expected to generate asymmetric selection on body size between the sexes, ultimately driving evolution of female-biased sexual size dimorphism. Additionally, it has been predicted that the intensity of fecundity selection increases when the opportunities for reproduction are reduced by the limiting thermal effects of increasing latitude-elevation (i.e. decreasing environmental temperatures) on the length of the reproductive season. This later factor would be particularly strong among ectotherms, where reproduction is heavily temperature-dependent. However, this integrative perspective on reproductive evolution by fecundity selection has rarely been investigated. Here, we employ a comparative approach to investigate these predictions in Liolaemus, a prominent lizard radiation. As expected, Liolaemus reproductive output (i.e. offspring number per reproductive episode) increases predictably with increasing female size. However, contrary to predictions, we found that increased fecundity does not translate into female-biased SSD, and that combined latitude-elevation does not impose a detectable effect on fecundity. Finally, our allometric analyses reveal that SSD scales with body size, which supports the occurrence of Rensch's rule in these lizards. We discuss the evolutionary implications of our results, and the assumptions of the investigated hypotheses. [ABSTRACT FROM AUTHOR]