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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]

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.)

Body size ( BS) varies in response to several selective pressures. In ectotherms, thermal inertia may affect thermoregulation, since larger BSs increase heat conservation as Bergmann originally stipulated for endotherms. However, Bergmann's rule is controversial in ectotherms. The heat balance hypothesis states that ectotherms' thermoregulatory capability is relevant for trends in BS. In cold climates, larger BSs would be advantageous for small thermoregulating ectotherms, by increasing heat conservation. However, BS implies a delaying effect on heating too; therefore, ectotherms may need another trait to compensate the later effect. Thermal melanism hypothesis posits that melanism increases heat gain, and may be adaptive for animals inhabiting cold climates. We propose that the higher solar radiation absorption from increased melanism may be such a compensatory trait. We expect BS and melanism to increase with latitude in response to seasonal temperatures and solar radiation. To test this, we studied the monophyletic L iolaemus goetschi group of lizard species across its 2200 km (32-48° S latitude) range. We used phylogenetically informed analyses to study geographic variation of BS and melanism (dorsal, ventral and total) in relation to temperatures, thermal amplitude, cloudiness and net solar radiation. Our results show that lizards' BS increases latitudinally in relation to thermal amplitude and temperature. Only ventral melanism varied latitudinally, but all melanism variables varied in response to cloudiness and net radiation. The relationship between BS and melanism was significant and positive in all cases. We suggest thermal inertia may be a fair candidate mechanism explaining geographic variation in BS (heat balance hypothesis), while melanism may influence heat gain according to the thermal melanism hypothesis. However, it remains unclear why latitudinal variation is related to ventral instead of dorsal melanism, and further investigation is needed to clarify the relationship between BS and melanism in light of cold climates. [ABSTRACT FROM AUTHOR]

Aim: There is an urgent need to explore, characterize, describe and preserve as many species as possible to prevent their decline. Tropical biodiversity hotspots harbour most of the known land diversity and vast amounts of undiscovered and undescribed species. Here, we quantify the taxonomically unassessed amphibian species richness in Madagascar, one of the best‐studied and explored tropical hotspots worldwide, to identify knowledge gaps and conservation implications. Location: Madagascar. Time Period: Present. Major Taxa Studied: Amphibians. Methods: We used the Madagascar amphibian fauna as a model to unveil neglected diversity by analysing 10,873 mitochondrial sequences using species delimitation algorithms and incorporating all previously published bioacoustics, distributional, morphological and nuclear data with an integrative approach. Results: Besides the currently described 413 species, we identified 408 divergent lineages. Among this, 310 fit the category of candidate species pending a taxonomic assessment, while 98 are considered deep conspecific lineages. These figures suggest that species richness could be twice as high as represented in the current taxonomy. Geographically, most of these candidate species occur in well‐studied areas within the island. Main Conclusions: Despite being one of the best‐studied and explored tropical countries worldwide for amphibians, we found that many species are awaiting a taxonomic assessment in Madagascar. Paradoxically, this unassessed diversity concentrates on highly explored regions, emphasizing the importance of exploring and inventorying new areas. Our results highlight the magnitude of the Linnean and Wallacean shortfalls, affecting both species richness estimates and the distribution ranges and biogeographic setting known for this fauna. Current conservation efforts should consider this novel diversity and unexplored areas as they will likely harbour yet many new species to be discovered. We expect similar patterns across less studied tropical realms and encourage researchers to perform such studies in different clades before this neglected biodiversity becomes irremediably lost. [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]

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.)

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 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]

The description of Liolaemus choique was based on an exhaustive morphological diagnosis. However, a posterior phylogeographic study suggested that it would be a junior synonym of L. smaug. Herein, we present morphological behavioral and distributional data indicating that L. choique would be considered as a valid species. Therefore, we suggest to revalidate L. choique, as a distinct taxon from L. smaug. [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]

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 feeding habits of a population of Liolaemus laurenti in northwest Argentina were studied in an annual period of activity. The objectives of the study were to determine the composition of the diet of the species, the trophic diversity and variations between sexes and among dry and wet seasons. From the analysis of 42 stomach contents, it was determined that ants constitute the main prey category of the diet, they comprise 93.15% of all present prey; it was also the most frequent category (100% of stomach contents). Lizard population also feeds on other insects and chelates. The trophic diversity was higher in females and in both in males and females increases during the wet season. Seasonal differences could be attributed to the fact that in arid ecosystems rainfall strongly affects productivity primary. Therefore the supply of resources for arthropods in general and therefore, for their predators. [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]

We coin the term 'nomenclatural harvesting' to identify a distinct form of taxonomic vandalism, in which practitioners generate taxon names for operational taxonomic units (OTUs) identified in phylogenetic trees published by others, even when there is no scientifically useful or practical basis for doing so. This practice can destabilize the nomenclature of scientifically established groups by swamping them with questionable new names, and this may have broader impacts in the application of taxon names to clinical toxinology, studies of biodiversity and conservation, and it may contribute to further erode the trust placed by the public in science. A change to Article 73 of the International Code of Zoological Nomenclature and the addition of suitable language in publications presenting taxonomic decisions to authenticate research effort and specimen work would alleviate the problem. [ABSTRACT FROM AUTHOR]

Copyright of Acta Zoologica Lilloana is the property of Fundacion Miguel Lillo 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 Acta Zoologica Lilloana is the property of Fundacion Miguel Lillo 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.)

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]

In this study, we analyzed the energy and reproductive cycles of female and male Gymnodactylus geckoides in the Caatinga area of northeast Brazil. We investigated whether these proxies of body condition, such as reproductive cells maturation and cellular structures changed in response to variation in abiotic and biotic factors (i.e., humidity, temperature, seasonality, body temperature, growing rate and gonad volume), using individuals stored under scientific conditions collected between September 2018 and December 2021. The condition factor showed an isometric growth pattern in the population studied. Meanwhile, the lipid, hepatic, and gonad factors correlated with body growth and showed monthly and seasonal variations, as well as reproductive cell maturation and cellular structure morphology. The cycles displayed constant replacement of energy reserves and mature reproductive cells, indicating constant and acyclic reproduction in G. geckoides. Energy reserves appear to be used for many reproductive activities, including meeting, gestation, and egg laying that occur at different frequencies during different periods in the dry and rainy seasons. Therefore, the reproductive cycle is likely to be strongly controlled by biotic factors, which are modeled using abiotic factors and environmental conditions (environmental patterns which proportionate greater resource availability). Our study is the first to investigate energy cycles and reproductive strategies in G. geckoides. It has shown that this species stores greater amounts of energy during the rainy season and then depletes these reserves during the dry period, since the rainy season correspond to the increase in energy consumption, mainly because of gestation and egg laying. [ABSTRACT FROM AUTHOR]

To investigate the effect of tinnitus and/or hyperacusis on distortion product otoacoustic emission (DPOAE) measures in adults with normal hearing thresholds from 0.25 to 8 kHz, while accounting for extended high-frequency (EHF) thresholds. A behavioural study consisted of comprehensive audiological assessment, validated tinnitus and hyperacusis questionnaires, DPOAE amplitudes and input/output (I/O) functions. Data of 56 participants with normal hearing were included for the analysis. Participants were categorised into four groups: (1) without tinnitus or hyperacusis, (2) with tinnitus only, (3) with hyperacusis only, and (4) with both tinnitus and hyperacusis. The groups with tinnitus showed elevated EHF thresholds compared with those without tinnitus. DPOAE amplitudes were not significantly affected by tinnitus and/or hyperacusis status; however, they were significantly affected by EHF thresholds. Further, no appreciable differences in DPOAE I/O functions were found across groups. The reported non-significant differences in DPOAEs in individuals with tinnitus and/or hyperacusis do not support a peripheral mechanism or an interaction between peripheral and central mechanisms underlying tinnitus or hyperacusis. Our findings, however, suggest the need to assess basal cochlear function (e.g. EHF thresholds) for a better understanding of differences in DPOAE measures in tinnitus and/or hyperacusis. [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]

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 mammalian cranium (skull without lower jaw) is representative of mammalian diversity and is thus of particular interest to mammalian biologists across disciplines. One widely retrieved pattern accompanying mammalian cranial diversification is referred to as 'craniofacial evolutionary allometry' (CREA). This posits that adults of larger species, in a group of closely related mammals, tend to have relatively longer faces and smaller braincases. However, no process has been officially suggested to explain this pattern, there are many apparent exceptions, and its predictions potentially conflict with well-established biomechanical principles. Understanding the mechanisms behind CREA and causes for deviations from the pattern therefore has tremendous potential to explain allometry and diversification of the mammalian cranium. Here, we propose an amended framework to characterise the CREA pattern more clearly, in that 'longer faces' can arise through several kinds of evolutionary change, including elongation of the rostrum, retraction of the jaw muscles, or a more narrow or shallow skull, which all result in a generalised gracilisation of the facial skeleton with increased size. We define a standardised workflow to test for the presence of the pattern, using allometric shape predictions derived from geometric morphometrics analysis, and apply this to 22 mammalian families including marsupials, rabbits, rodents, bats, carnivores, antelopes, and whales. Our results show that increasing facial gracility with size is common, but not necessarily as ubiquitous as previously suggested. To address the mechanistic basis for this variation, we then review cranial adaptations for harder biting. These dictate that a more gracile cranium in larger species must represent a structural sacrifice in the ability to produce or withstand harder bites, relative to size. This leads us to propose that facial gracilisation in larger species is often a product of bite force allometry and phylogenetic niche conservatism, where more closely related species tend to exhibit more similar feeding ecology and biting behaviours and, therefore, absolute (size-independent) bite force requirements. Since larger species can produce the same absolute bite forces as smaller species with less effort, we propose that relaxed bite force demands can permit facial gracility in response to bone optimisation and alternative selection pressures. Thus, mammalian facial scaling represents an adaptive by-product of the shifting importance of selective pressures occurring with increased size. A reverse pattern of facial 'shortening' can accordingly also be found, and is retrieved in several cases here, where larger species incorporate novel feeding behaviours involving greater bite forces. We discuss multiple exceptions to a bite force-mediated influence on facial proportions across mammals which lead us to argue that ecomorphological specialisation of the cranium is likely to be the primary driver of facial scaling patterns, with some developmental constraints as possible secondary factors. A potential for larger species to have a wider range of cranial functions when less constrained by bite force demands might also explain why selection for larger sizes seems to be prevalent in some mammalian clades. The interplay between adaptation and constraint across size ranges thus presents an interesting consideration for a mechanistically grounded investigation of mammalian cranial allometry., (© 2023 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.)

Copyright of Methods in Ecology & Evolution is the property of Wiley-Blackwell 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 medial olivocochlear (MOC) reflex provides unmasking of sounds in noise, but its contribution to speech-in-noise perception remains unclear due to conflicting results. This study determined associations between MOC reflex strength and sentence recognition in noise in individuals with normal hearing. MOC reflex strength was assessed using contralateral inhibition of transient-evoked otoacoustic emissions (TEOAEs). Scores on the AzBio sentence task were quantified at three signal-to-noise ratios (SNRs). Additionally, slope and threshold of the psychometric function were computed. Associations between MOC reflex strength and speech-in-noise outcomes were assessed using Spearman rank correlations. Nineteen young adults with normal hearing participated, with data from 17 individuals (mean age = 21.8 years) included in the analysis. Contralateral noise significantly decreased the amplitude of TEOAEs. A range of contralateral inhibition values was exhibited across participants. Scores increased significantly with increasing SNR. Contrary to hypotheses, there were no significant correlations between MOC reflex strength and score, nor were there any significant correlations between MOC reflex strength and measures of the psychometric function. Results found no significant monotonic relationship between MOC reflex strength and sentence recognition in noise. Future work is needed to determine the functional role of the MOC reflex. [ABSTRACT FROM AUTHOR]

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Roughly 18,000 species are described annually as new to science, while estimated extinction rates are comparable to or even exceeding these new discoveries. Considering the estimates of up to 15 million extant eukaryotic species on Earth, of which only about 2 million have been described so far, there has been a recent 'boom' of new potential approaches to more quickly discover and describe the millions of unknown species. This deficit is particularly noted in hyperdiverse taxa, as the current rate of species discovery is considered too slow. Recently, a 'minimalist' alpha taxonomic approach was proposed, relying solely on DNA barcoding and a habitus photograph, in a claimed effort to expedite the naming of new species to combat the so-called taxonomic impediment. In this paper, we point to limitations of minimalist taxonomy, present arguments in favour of the integrative approach, and finally explore a number of potential solutions to combat the taxonomic impediment in hyperdiverse taxa without sacrificing utility and quality for apparent speed and quantity. [ABSTRACT FROM AUTHOR]

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. [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 correlations between phenotypic and environmental traits characterize adaptive radiations. However, the lizard genus Liolaemus, one of the most ecologically diverse terrestrial vertebrate radiations on earth, has so far shown limited or mixed evidence of adaptive diversification in phenotype. Restricted use of comprehensive environmental data, incomplete taxonomic representation and not considering phylogenetic uncertainty may have led to contradictory evidence. We compiled a 26‐taxon dataset for the Liolaemus gracilis species group, representing much of the ecological diversity represented within Liolaemus and used environmental data to characterize how environments occupied by species' relate to phenotypic evolution. Our analyses, explicitly accounting for phylogenetic uncertainty, suggest diversification in phenotypic traits toward the present, with body shape evolution rapidly evolving in this group. Body shape evolution correlates with the occupation of different structural habitats indicated by vegetation axes suggesting species have adapted for maximal locomotory performance in these habitats. Our results also imply that the effects of phylogenetic uncertainty and model misspecification may be more extensive on univariate, relative to multivariate analyses of evolutionary correlations, which is an important consideration in analyzing data from rapidly radiating adaptive radiations. [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]

Obligate parthenogenesis evolved in reptiles convergently several times, mainly through interspecific hybridization. The obligate parthenogenetic complexes typically include both diploid and triploid lineages. Offspring of parthenogenetic hybrids are genetic copies of their mother; however, the cellular mechanism enabling the production of unreduced cells is largely unknown. Here, we show that oocytes go through meiosis in three widespread, or even strongly invasive, obligate parthenogenetic complexes of geckos, namely in diploid and triploid Lepidodactylus lugubris, and triploid Hemiphyllodactylus typus and Heteronotia binoei. In all four lineages, the majority of oocytes enter the pachytene at the original ploidy level, but their chromosomes cannot pair properly and instead form univalents, bivalents and multivalents. Unreduced eggs with clonally inherited genomes are formed from germ cells that had undergone premeiotic endoreplication, in which appropriate segregation is ensured by the formation of bivalents made from copies of identical chromosomes. We conclude that the induction of premeiotic endoreplication in reptiles was independently co-opted at least four times as an essential component of parthenogenetic reproduction and that this mechanism enables the emergence of fertile polyploid lineages within parthenogenetic complexes. [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]

The adult ankle of early reptiles had five distal tarsal (dt) bones, but in Dinosauria, these were reduced to only two: dt3 and dt4, articulated to metatarsals (mt) mt3 and mt4. Birds have a single distal tarsal ossification center that fuses to the proximal metatarsals to form a new adult skeletal structure: the composite tarsometatarsus. This ossification center develops within a single large embryonic cartilage, but it is unclear if this cartilage results from fusion of earlier cartilages. We studied embryos in species from four different bird orders, an alligatorid, and an iguanid. In all embryos, cartilages dt2, dt3, and dt4 are formed. In the alligatorid and the iguanid, dt2 failed to ossify: only dt3 and dt4 develop into adult bones. In birds, dt2, dt3, and dt4 fuse to form the large distal tarsal cartilage; the ossification center then develops above mt3, in cartilage presumably derived from dt3. During the entire dinosaur–bird transition, a dt2 embryonic cartilage was always formed, as inferred from the embryology of extant birds and crocodilians. We propose that in the evolution of the avian ankle, fusion of cartilages dt3 and dt2 allowed ossification from dt3 to progress into dt2, which began to contribute bone medially, while fusion of dt3 to dt4 enabled the evolutionary loss of the dt4 ossification center. As a result, a single ossification center expands into a plate‐like unit covering the proximal ends of the metatarsals, that is key to the development of an integrated tarsometatarsus. Research Highlights: Modern birds currently develop a single ossification center in their distal ankle. We document how three distal tarsal cartilages (dt2, dt3, and dt4) are formed, that fuse to form a single cartilage. The position of the ossification center suggests it begins in cartilage derived from dt3.During the entire evolutionary transition from dinosaurs to early birds, only dt3 and dt4 formed adult independent bones. However, a dt2 embryonic cartilage was always formed, as inferred from the embryology of extant birds and crocodilians.We propose that cartilage fusion allowed ossification starting from dt3 to progress into dt2 and dt4; this allowed dt2 to contribute bone medially, and dt4 to lose its ossification center. As a result, a single embryonic bone covers the proximal metatarsals, arguably a key step in the development of an integrated tarsometatarsus. [ABSTRACT FROM AUTHOR]