Are mountain habitats becoming more suitable for generalist than cold-adapted lizards thermoregulation?

The Shape of Water: Physiological Adaptations to Habitat Aridity in the Ornate Tree Lizard (Urosaurus ornatus)

Deserts have always amazed researchers due to their high diversity of habitats, where plant and animal species have been able to adapt and diversify, even when these areas impose several constraints on an organism's activity patterns. In particular, deserts support several lizard species adapted to the thermal and water restrictions found in such biomes. Although several studies have attempted to understand how lizard species might respond to water deficits or droughts in deserts, few have addressed how these responses might vary along a latitudinal gradient. This raises the question of whether physiological buffering of the organism or the climatic environment affects water loss in lizards. Here, we used six populations of Urosaurus ornatus to test whether water loss is influenced more by the intrinsic physiology of the lizard or by the climatic niche. We found that water loss is primarily influenced by the climatic niche of the lizard. However, future studies should focus on how microclimatic variables can influence water loss in organisms found across large latitudinal gradients.

Genetic diversity, phylogenetic position, and co-phylogenetic relationships of Karyolysus, a common blood parasite of lizards in the western Mediterranean

The genus Karyolysus was originally proposed to accommodate blood parasites of lacertid lizards in Western Europe. However, recent phylogenetic analyses suggested an inconclusive taxonomic position of these parasites of the order Adeleorina based on the available genetic information. Inconsistencies between molecular phylogeny, morphology, and/or life cycles can reflect lack of enough genetic information of the target group. We therefore surveyed 28 localities and collected blood samples from 828 lizards of 23 species including lacertids, skinks, and geckoes in the western Mediterranean, North Africa, and Macaronesia, where species of Karyolysus and other adeleorine parasites have been described. We combined molecular and microscopic methods to analyze the samples, including those from the host type species and the type locality of Karyolysus bicapsulatus. The phylogenetic relationship of these parasites was analyzed based on the 18S rRNA gene and the co-phylogenetic relationship with their vertebrate hosts was reconstructed. We molecularly detected adeleorine parasites in 37.9% of the blood samples and found 22 new parasite haplotypes. A phylogenetic reconstruction with 132 sequences indicated that 20 of the newly detected haplotypes clustered in a well-supported clade with another 18 sequences that included Karyolysus galloti and Karyolysus lacazei. Morphological evidence also supported that K. bicapsulatus clustered in this monophyletic clade. These results supported the taxonomic validity of the genus. In addition, we found some parasite haplotypes that infected different lizard host genera with ancient diverging histories, which suggested that Karyolysus is less host-specific than other blood parasites of lizards in the region. A co-phylogenetic analysis supported this interpretation because no significant co-speciation signal was shown between Karyolysus and lizard hosts.

Season-sex interaction induces changes in the ecophysiological traits of a lizard in a high altitude cold desert, Puna region

Functional traits are those characteristics of organisms that influence the ability of a species to develop in a habitat and persist in the face of environmental changes. The traits are often affected by a multiplicity of species-dependent and external factors. Our objective was to investigate thermal biology of Liolaemus ruibali in a high altitude cold desert at the arid Puna region, Argentina. We address the following question: do sex and seasonal variations in environmental temperature induce changes in the ecophysiological traits? We measured and compared the operative temperatures between fall and spring; and between sexes and seasons, we compared the ecophysiological traits of lizards, microenvironmental temperatures and thermoregulatory behavior. Air and operative temperatures were different between seasons. We found an effect of season-sex interaction on field body temperatures, preferred temperatures, panting threshold and thermal quality. The voluntary and critical temperatures presented seasonal variation in relation to changes in environmental temperatures, suggesting thermal acclimatization. We note behavioral changes between seasons, with the substrate being the main resource for gaining heat in spring. We conclude that Liolaemus ruibali is an efficient thermoregulator; it is a eurythermic lizard and presents phenotypic plasticity in different ecophysiological and behavioral traits induced by sex and seasonality. In addition, we predict that this population could buffer the effects of projected global warming scenarios.

The risk of forfeiting the ranges of reptiles under nonrandom and stochastic scenarios of moving climate conditions: a case study for 115 species in China

Revealing the hazard features of forfeiting areal ranges for nonidentical scenarios of shifting climatic conditions is pivotal for the conformation of reptiles to climatic warming. Taking 115 reptiles in China as an example, the indefiniteness and danger of shrinking geographical range for the reptiles under stochastic and nonrandom scenarios of moving climatic situations were inspected via exploiting the scenarios of shifting climatic status associated with the representative concentration pathways, Monte Carlo simulation, and the classifications scheme based on the fuzzy set. For non-stochastic states of altering climatic elements, the richness of 115 reptiles improved in certain sites of northeastern, and western China and dropped in several areas of northern, eastern, central China, and southeastern China: roughly 59-74 reptiles forfeiting less than 20% of their present ranges, roughly 25-34 reptiles narrowing less than 20-40% of their present areal ranges, and roughly 105-111 reptiles inhabited more than 80% of their overall areal ranges. For the random status of shifting climatic elements, the count of reptiles that forfeited the various extent of the present or entire areal ranges descended with raising the eventuality; with a possibility of over 0.6, the count of reptiles that minified less than 20%, 20-40%, 40-60%, 60-80% and over 80% of the present ranges was roughly 28-49, 5-10, 1-3, 0-1 and 13-18, separately; the count of reptiles that inhabited below 20%, 20-40%, 40-60%, 60-80% and more than 80% of the entire real ranges was roughly 0-1, 5-6, 1-5, 0-2 and 35-36, separately. About 30% of 115 reptiles would face disappearance danger in response to moving climate conditions in the absence of adaption steps, and the conformation measures were indispensable for the reptiles that shrunk their areas.

Connectivity Predicts Presence but Not Population Density in the Habitat-Specific Mountain Lizard Iberolacerta martinezricai

The Batuecan lizard Iberolacerta martinezricai is a critically endangered species due to its significantly reduced distribution, which is restricted to the scree slopes (SS) of a few mountain peaks within the Batuecas-Sierra de Francia Natural Park (western Spain). Given its high specialisation in this type of discontinuous habitat, the long-term conservation of the species requires maintaining the connectivity between populations. This study analyses the contribution of connectivity, as well as other patch-related factors, in the distribution and density patterns of the species. With this aim, 67 SS were sampled by line transects from May to October 2018. Each SS was characterised using variables indicative of the microhabitat conditions for the lizard. Inter-SS connectivity was quantified using graph theory for seven distances. Generalised linear models (GLMs) were performed for both presence and density. Model results showed that while connectivity was a relevant factor in the presence of lizards, density only involved patch-related variables. Discrepancies probably occurred because the factors influencing presence operate on a wider scale than those of abundance. In view of the results, the best-connected SS, but also those where the lizard is most abundant and from which more dispersed individuals are likely to depart, seem to be the essential patches in any conservation strategy. The results may also be relevant to other species with habitat-specific requirements.

Plasticity of haemoglobin concentration and thermoregulation in a mountain lizard

The plastic capability of species to cope with the new conditions created by climate change is poorly understood. This is particularly relevant for organisms restricted to high elevations because they are adapted to cold temperatures and low oxygen availability. Therefore, evaluating trait plasticity of mountain specialists is fundamental to understand their vulnerability to environmental change. We transplanted mountain lizards, Iberolacerta cyreni, 800 m downhill to evaluate the plastic response in body condition, thermoregulation traits, haemoglobin level, and haemoparasite load. Initial measurements of body mass, total haemoglobin concentration ([Hb]), hematic parasite intensities, dorsal luminance, and thermoregulatory behaviour were resampled after two and four weeks of acclimation. We also tested whether an anti-parasitic drug reduced haemoparasite intensity. After only two weeks of acclimation to a lower elevation, lizards decreased 42% in [Hb], had 17% less parasite intensities, increased body condition by 25%, and raised by ~3% their mean preferred temperatures and their voluntary thermal maximum. The anti-parasitic treatment had no significant effect on the intensity of hematic parasites, but our results suggest that negative effects of haemoparasites on [Hb] are relaxed at lower elevation. The rapid plastic changes observed in thermal preferences, body condition, [Hb], and parasite intensity of I. cyreni demonstrate a potential plastic response of a mountain specialist. This may be adaptive under the climatic extremes typical of mountain habitats. However, there is uncertainty in whether the observed plasticity can also help overcome long term environmental changes.

Unraveling the influences of climate change in Lepidosauria (Reptilia)

In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans and many species have shifted their geographic ranges, seasonal activities, migration patterns, abundances and interactions in response to these changes. Projections of future climate change are uncertain, but the Earth's warming is likely to exceed 4.8 °C by the end of 21th century. The vulnerability of a population, species, group or system due to climate change is a function of impact of the changes on the evaluated system (exposure and sensitivity) and adaptive capacity as a response to this impact, and the relationship between these elements will determine the degree of species vulnerability. Predicting the potential future risks to biodiversity caused by climate change has become an extremely active field of research, and several studies in the last two decades had focused on determining possible impacts of climate change on Lepidosaurians, at a global, regional and local level. Here we conducted a systematic review of published studies in order to seek to what extent the accumulated knowledge currently allow us to identify potential trends or patterns regarding climate change effects on lizards, snakes, amphisbaenians and tuatara. We conducted a literature search among online literature databases/catalogues and recorded 255 studies addressing the influence of climate change on a total of 1918 species among 49 Lepidosaurian's families. The first study addressing this subject is dated 1999. Most of the studies focused on species distribution, followed by thermal biology, reproductive biology, behavior and genetics. We concluded that an integrative approach including most of these characteristics and also bioclimatic and environmental variables, may lead to consistent and truly effective strategies for species conservation, aiming to buffer the climate change effects on this group of reptiles.

Main factors affecting lacertid lizard thermal ecology

The thermal ecology of ectotherms has been studied for almost 2 centuries, but additional attention is currently being paid to it, to understand how organisms deal with the environment in a climate change context. A consensus is still far away due to the large number of factors involved and their complex interactions. In this context, 3 analyses in lacertid lizards were carried out: (i) a meta-analysis, to test for differences between body and air temperatures from 71 populations; (ii) a meta-analysis concerning correlations between body and air temperatures from 60 populations; and (iii) a multimodel inference of thermoregulation effectiveness indices from 45 populations. The importance of different factors, including body size, habitat, insularity, altitude, climate and season, was evaluated in all analyses to model the response variables. A strong seasonality effect was observed, with a consistent pattern of less effective thermoregulation in summer compared to other seasons. Altitude was the second most important factor, with a consistent higher thermoregulation effort in populations occurring at high elevations (>1000 m above sea level). Other factors, such as insularity or body size, can also be important, but did not exhibit a clear pattern. Finally, thermoregulation was less affected by climate and habitat type.

Aspects of thermal ecology of the meadow lizard (Darevskia praticola)

We studied the thermal biology of the meadow lizard (Darevskia praticola) in the peripheral part of its distribution range (westernmost edge of the distribution area). We assessed whether these lizards actively thermoregulate, estimated the accuracy and effectiveness of thermoregulation, and evaluated the thermal quality of the habitat using the standard thermal parameters: body (), preferred () with set-point range () and operative temperatures (). of the meadow lizard under controlled laboratory conditions was between 27.8°C and 31.4°C. In the field and averaged 29.0°C and 26.1°C, respectively. A large proportion of s fell below the range of the meadow lizard, and lizard s were substantially closer to the species’ range. Obtained values of thermoregulatory indices suggested that the meadow lizard thermoregulated actively, with a rather high accuracy () and effectiveness ( and ), and that their habitat at this locality was thermally favourable during the spring. Our results suggest that thermal requirements of the meadow lizard resemble those of alpine lacertids, while their s and are lower than in most lacertid lizards. Further thermoregulation studies could be an important step in predicting the impact of the global climate change on the meadow lizard and the risks of local extinctions of its peripheral populations.

Wind constraints on the thermoregulation of high mountain lizards

Thermal biology of lizards affects their overall physiological performance. Thus, it is crucial to study how abiotic constraints influence thermoregulation. We studied the effect of wind speed on thermoregulation in an endangered mountain lizard (Iberolacerta aurelioi). We compared two populations of lizards: one living in a sheltered rocky area and the other living in a mountain ridge, exposed to strong winds. The preferred temperature range of I. aurelioi, which reflects thermal physiology, was similar in both areas, and it was typical of a cold specialist. Although the thermal physiology of lizards and the structure of the habitat were similar, the higher wind speed in the exposed population was correlated with a significant decrease in the effectiveness thermoregulation, dropping from 0.83 to 0.74. Our results suggest that wind reduces body temperatures in two ways: via direct convective cooling of the animal and via convective cooling of the substrate, which causes conductive cooling of the animal. The detrimental effect of wind on thermoregulatory effectiveness is surprising, since lizards are expected to thermoregulate more effectively in more challenging habitats. However, wind speed would affect the costs and benefits of thermoregulation in more complex ways than just the cooling of animals and their habitats. For example, it may reduce the daily activity, increase desiccation, or complicate the hunting of prey. Finally, our results imply that wind should also be considered when developing conservation strategies for threatened ectotherms.

Adaptive seasonal shifts in the thermal preferences of the lizard Iberolacerta galani (Squamata, Lacertidae)

The León rock lizard, Iberolacerta galani, lives in isolated mountains of Spain. We studied the seasonal changes in the thermal biology of I. galani between spring and summer. We calculated precision, accuracy and effectiveness of thermoregulation and the habitat thermal quality for spring, and compared with the values of summer. In addition, we studied how the shift in the thermal preferences of lizards would contribute to achieve a higher effectiveness of thermoregulation. Thermal preferences of León rock lizards are among the lowest in lacertids, and are also very narrow, maintaining the narrowness among seasons. As for summer (27.90-29.70°C, mean value =28.76°C), the thermal preferences of I. galani are also low in spring (29.60-31.10°C, mean value =30.38°C), supporting the idea that this species is adapted to cold environments. The habitat thermal quality is lower in spring (10.99°C) than in summer (9.36°C), while the effectiveness of thermoregulation is higher in spring (0.92) than in summer (0.80). We found that the seasonal shift in thermal preferences contributes significantly to enhance the effectiveness of thermoregulation in both seasons, more in spring (0.45°C) than in summer (0.16°C). Because I. galani inhabits isolated mountains, where the activity period is reduced from April to October, we hypothesize that the observed adaptation of the thermal preferences, which enhance thermoregulation to a larger extent in spring, may evolved to maximize performance during the reproductive season.

Sexual differences in behavioral thermoregulation of the lizard Scelarcis perspicillata

Temperature determines all aspects of the biology of ectotherms. Although sexual differences in thermal ecology are not the rule in lizards, some species exhibit such differences. We studied the effect of sex and reproductive condition on the thermoregulation of an introduced population of Scelarcis perspicillata during the summer in Menorca (Balearic Islands, Spain). These lizards live in the wall surfaces of a limestone quarry, where the sun is scarce because of the narrowness of the quarry walls. The population is sexually dimorphic, with larger males than females. We measured body temperature (T_b) of adult males and females in the field, and air (T_a) and substrate temperature (T_s) at the capture sites, and recorded exposure to sunlight, height of the perch, and type of substrate. We also recorded operative temperatures (T_e) as a null hypothesis of thermoregulation. Finally, we studied the thermal preferences of adult males and females in a laboratory thermal gradient. Thermal preferences were similar for pregnant and non-pregnant females, and sex did not affect the thermal preferences of lizards, even after controlling for the effect of body size. However, in the field, females achieved higher T_b than males, and occupied microhabitats with higher T_a and T_s and lower perch heights than males. Furthermore, females selected perches in full sun at a higher frequency than males. As a consequence, females achieved a higher accuracy and effectiveness of thermoregulation (0.89) than males (0.84). Thus, all else being equal, females would achieve a higher performance than males. The observed results are attributable to sexual differences in behaviour, probably in relation with the reproductive season.