Lizard Psammodromus Algirus Research Articles

Mounting an immune response reduces male attractiveness in a lizard.

Parasites impact host fitness and constitute an important selective pressure on the host's life history. According to parasite-mediated sexual selection, ornaments are presumed to honestly indicate immune capacity or resistance against parasites, and the chooser sex (typically females) obtains an advantage by selecting more ornamented, thus more immunocompetent mates. Therefore, signalers mounting an immune response must allocate resources from the sexual signal to the immune system, hence reducing the expression of the ornament and becoming less attractive to the choosing sex. Here, we test this idea in the lizard Psammodromus algirus. We inoculated a subsample of males with lipopolysaccharide (LPS) of the cell wall of Escherichia coli, while others served as sham controls. The inoculation of LPS decreased the proportion of ergosterol (pro-vitamin D2) in femoral secretions, and chemosensory tests showed that the scent of LPS-inoculated males was less attractive to females than the scent of control males. Given that ergosterol is a precursor of vitamin D, which has physiological functions as an immune modulator, immunocompromised males likely needed to divert vitamin D to the immune system, reducing the allocation of ergosterol to secretions. In this way, females could detect "sick" males, preferring the apparently healthy males. Overall, our study shows that mounting an immune response is costly in terms of reduced attractiveness. Moreover, we disentangle the underlying mechanism, which involves an honest signal based on vitamin D allocation.

Lizard abundance in forest fragments: effects of patch size, patch shape, thermoregulation, and habitat quality

Abstract The effects of forest fragmentation on ecosystems are pervasive, but little is known about the factors that influence lizard abundance in fragmented landscapes. We studied the roles of patch size and shape, thermal quality, and refuge availability as predictors of the relative abundance of Psammodromus algirus lizards at deciduous or evergreen forest fragments surrounded by cereal fields. Relative abundance, based on time-controlled counts, decreased from the northeast (dominated by deciduous habitat) to the southwest (with a higher cover of croplands, and dominated by evergreen habitat). Refuge availability was correlated with this gradient, decreasing from the northeast to the southwest and being larger in deciduous than in evergreen fragments. After controlling for the effects of this environmental variation, lizard abundance increased as perimeter-to-area ratio (P/A) decreased (and consequently as fragment size increased). Although the effects of thermal quality as such were negligible, our results can be interpreted in the light of thermoregulatory requirements; given the low temperatures available at shaded locations, lizards should actively select sunlit patches while they try to minimize predation risk by basking as close as possible to the nearest refuge. Although use of fragment edges as basking sites is expected to increase with P/A ratio, lizards should avoid using them as basking sites, because both exposure to predators and risk of overheating are expected to be higher at edges and croplands than inside fragments. We conclude that long and narrow forest strips with high P/A ratios could act as ecological traps rather than as dispersion-promoting corridors.

Lizard thermoregulation revisited after two decades of global warming

Abstract Although the effects of global warming on thermoregulation are usually explored using predictions of climate envelop modelling, such effects should best be analysed empirically, studying the same population with the same methods after a long enough period of temperature rise. We used a 30‐year long database about body temperatures (Tbs) of field‐active Psammodromus algirus lizards inhabiting a well‐conserved temperate open forest, and we focused on the summers of 1997 and 2017 to compare Tbs, environmental operative temperatures (Tes), their proximity to the selected thermal range (Tsel), and the selection of sunlit and shaded patches all along the day. From these data, we estimated the precision (standard deviation of Tbs), accuracy (average distance between Tbs and Tsel) and effectiveness (extent to which Tbs are closer to Tsel than Tes) of thermoregulation. Of the highest 5% of all Tbs in the database, 95% were recorded in 2017, when the adjustment to Tsel was much better for Tbs selected in a laboratory thermogradient than for field Tbs (percentages of Tbs above Tsel of 2% and 52% respectively). In 2017, especially after 12:00 h, the selection of shaded patches (87% of lizards in full shade vs. <1% in full sun) was more intense than in 1997, contributed more to overall thermoregulation, and produced a larger difference between Tes and Tbs. In spite of this, Tbs were lower—and closer to Tsel—in 1997 (when most shaded patches offered favourable thermal opportunities, with Tes within or below Tsel) than in 2017 (when only 33% of full shade Tes, and 8% of all Tes, were within or below Tsel). As a consequence, estimates of the accuracy and effectiveness of thermoregulation decreased over the 20‐year period examined. We conclude that given the low availability of Tes within or below Tsel, lizards cannot longer prevent the rise of their Tbs above Tsel, at least in hot summer days. Thus, the effects of global warming are already hindering the ability of lizards to buffer environmental change by behavioural means, even in temperate forests with a fine‐grained mosaic of sun and shade patches. Read the free Plain Language Summary for this article on the Journal blog.

Longitudinal effects of habitat quality, body condition, and parasites on colour patches of a multiornamented lizard

Ontogeny is expected to be a determinant factor affecting production of colour patches in lizards, while immune challenges or sudden weight loss may impair the maintenance of pigment-based coloration within a breeding season. We translocated males of the lizard Psammodromus algirus between two sampling plots that differed in distance to a road, vegetation structure, and predator abundance. We analysed variation in spectral reflectance of their colour patches the same and the following year. The change in the reflectance of the lizard colour patches within the first breeding season was explained by the interaction between plot and treatment, but not body condition. The maintenance of the breeding coloration was impaired only in those males translocated close to the road, probably reflecting that it is a poor-quality habitat for P. algirus. The following year, lizards that produced a more elaborate coloration were those that increased their body condition and controlled some parasitic infections, although suffered an increase of others. This study shows that colour patch production is plastic in P. algirus. Lizards increasing parasites or losing weight reduced pigmentation, although habitat quality can cushion these negative effects on pigmentation. However, not all parasites constrain the investment in coloration. In fact, some increased in those lizards that allocated more pigments to colour patches. In conclusion, longitudinal studies following experimental manipulation can contribute to understand pigment allocation rules in lizards.Significance statementPigments involved in colour patches of animals are limiting resources that can be reallocated off the skin to other functions. However, longitudinal evidence of this phenomenon is scarce in reptiles. We designed a manipulative mark-recapture experiment to investigate effects of habitat and parasitic infections on colour patch maintenance (within-year variation) and production (between-year variation) in male free-ranging lizards that were reciprocally translocated between two patches of habitat that differed in quality. During the first year, lizards translocated to the habitat with more predators and worse vegetation impoverished their coloration, while lizards translocated to the more favourable habitat maintained it despite all translocated lizards loose body condition. The next year we detected different effects on the coloration of three different parasites investigated, suggesting that coloration can reflect the virulence of the infections.

Low genome-wide divergence between two lizard populations with high adaptive phenotypic differentiation.

Usually, adaptive phenotypic differentiation is paralleled by genetic divergence between locally adapted populations. However, adaptation can also happen in a scenario of nonsignificant genetic divergence due to intense gene flow and/or recent differentiation. While this phenomenon is rarely published, findings on incipient ecologically driven divergence or isolation by adaptation are relatively common, which could confound our understanding about the frequency at which they actually occur in nature. Here, we explore genome‐wide traces of divergence between two populations of the lacertid lizard Psammodromus algirus separated by a 600 m elevational gradient. These populations seem to be differentially adapted to their environments despite showing low levels of genetic differentiation (according to previously studies of mtDNA and microsatellite data). We performed a search for outliers (i.e., loci subject to selection) trying to identify specific loci with FST statistics significantly higher than those expected on the basis of overall, genome‐wide estimates of genetic divergence. We find that local phenotypic adaptation (in terms of a wide diversity of characters) was not accompanied by genome‐wide differentiation, even when we maximized the chances of unveiling such differentiation at particular loci with FST‐based outlier detection tests. Instead, our analyses confirmed the lack of genome‐wide differentiation on the basis of more than 70,000 SNPs, which is concordant with a scenario of local adaptation without isolation by environment. Our results add evidence to previous studies in which local adaptation does not lead to any kind of isolation (or early stages of ecological speciation), but maintains phenotypic divergence despite the lack of a differentiated genomic background.

Fire reduces parasite load in a Mediterranean lizard.

Wildfires are a natural disturbance in many ecosystems. However, their effect on biotic interactions has been poorly studied. Fire consumes the vegetation and the litter layer where many parasites spend part of their life cycles. We hypothesize that wildfires reduce habitat availability for parasites with consequent potential benefits for hosts. We tested this for the lizard Psammodromus algirus and its ectoparasites in a Mediterranean ecosystem. We predicted that lizards in recently burned areas would have lower parasite load (cleaning effect) than those in unburned areas and that this phenomenon implies that lizards spending their entire lives in postfire conditions experience a lower level of parasitism than those living in unburned areas. We compared the ectoparasite load of lizards between eight paired burned/unburned sites, including recent (less than 1 year postfire) and older fires (2-4 years). We found that lizards' ectoparasites prevalence was drastically reduced in recently burned areas. Likewise, lizards in older burned areas showed less evidence of past parasitic infections. Fire disrupted the host-parasite interaction, providing the opportunity for lizards to avoid the negative effects of ectoparasites. Our results suggest that wildfires probably fulfil a role in controlling vector-borne diseases and pathogens, and highlight ecological effects of wildfires that have been overlooked.

Environmental association modelling with loci under divergent selection predicts the distribution range of a lizard.

During the historical building of a species range, individual colonizers have to confront different ecological challenges, and the capacity of the species to broaden its range may depend on the total amount of adaptive genetic variation supplied by evolution. We set out to increase our understanding of what defines a range and the role of underlying genetics by trying to predict an entire species' range from the geographical distribution of its genetic diversity under selection. We sampled five populations of the western Mediterranean lizard Psammodromus algirus that inhabit a noticeable environmental gradient of temperature and precipitation. We correlated the genotypes of 95 individuals (18-20 individuals per population) for 21 SNPs putatively under selection with environmental scores on a bioclimatic gradient, using 1 × 1km2 grid cells as sampling units. By extrapolating the resulting model to all possible combinations of alleles, we inferred all the geographic cells that were theoretically suitable for a given amount of genetic variance under selection. The inferred distribution range overlapped to a large extent with the realized range of the species (77.46% of overlap), including an accurate prediction of internal gaps and range borders. Our results suggest an adaptability threshold determined by the amount of genetic variation available that would be required to warrant adaptation beyond a certain limit of environmental variation. These results support the idea that the expansion of a species' range can be ultimately linked to the arising of new variants under selection (either newly selected variants from standing genetic variation or innovative mutations under selection).

Inter-Individual Differences in Ornamental Colouration in a Mediterranean Lizard in Relation to Altitude, Season, Sex, Age, and Body Traits

Animals frequently show complex colour patterns involved in social communication, which attracts great interest in evolutionary and behavioural ecology. Most researchers interpret that each colour in animals with multiple patches may either signal a different bearer’s trait or redundantly convey the same information. Colour signals, moreover, may vary geographically and according to bearer qualities. In this study, we analyse different sources of colour variation in the eastern clade of the lizard Psammodromus algirus. Sexual dichromatism markedly differs between clades; both possess lateral blue eyespots, but whereas males in the western populations display strikingly colourful orange-red throats during the breeding season, eastern lizards only show some commissure pigmentation and light yellow throats. We analyse how different colour traits (commissure and throat colouration, and the number of blue eyespots) vary according to body size, head size (an indicator of fighting ability), and sex along an elevational gradient. Our findings show that blue eyespots function independently from colour patches in the commissure and throat, which were interrelated. Males had more eyespots and orange commissures (which were yellow or colourless in females). Throat colour saturation and the presence of coloured commissures increased in older lizards. The number of eyespots, presence of a coloured commissure, and throat colour saturation positively related to head size. However, while the number of eyespots was maximal at lowlands, throat colour saturation increased with altitude. Overall, our results suggest that this lizard harbours several colour signals, which altitudinally differ in their importance, but generally provide redundant information. The relevance of each signal may depend on the context. For example, all signals indicate head size, but commissure colouration may work well at a short distance and when the lizard opens the mouth, while both throat and eyespots might work better at long distance. Meanwhile, throat colouration and eyespots probably work better in different light conditions, which might explain the altitudinal variation in the relative importance of each colour component.

Fire-driven behavioral response to smoke in a Mediterranean lizard

Abstract The evolutionary role of fire in animals has been poorly explored. Reptiles use sensory cues, such as smell (chemoreception), to detect threats and flee. In Mediterranean ecosystems, fire is a threat faced by reptiles. We hypothesized that the Mediterranean lizard Psammodromus algirus recognizes the threat of fire by detecting the smoke, which triggers a behavioral response that enhances survival in fire-prone ecosystems. We predicted that lizards from fire-prone ecosystems will be more sensitive to fire stimulus than those from ecosystems that rarely burn. We conducted a terrarium experiment in which lizards from habitats with contrasted fire regimes (fire-prone vs. non-fire-prone) were exposed to smoke versus control (false smoke) treatment. We found that, in populations from fire-prone habitats, more lizards reacted to smoke, and their behavioral response was more intense than in lizard populations from non-fire-prone habitats. Our results suggest that an enhanced response to smoke may be adaptive in lizards from fire-prone ecosystems as it increases the chance for survival. We provide evidence that fire is likely an evolutionary driver shaping behavioral traits in lizard populations exposed to frequent wildfires. Understanding ecological and evolutionary processes shaping animal populations is relevant for species conservation in a changing fire regime world.

Long-term trace element assessment after a mine spill: Pollution persistence and bioaccumulation in the trophic web

Trace elements can be toxic when they cannot be easily removed after entering an ecosystem, so a long-term assessment is fundamental to guide ecosystem restoration after catastrophic pollution. In 1998, a pyrite mining accident in Aznalcóllar (south-western Spain) spilled toxic waste over a large area of the Guadiamar river basin, where, after restoration tasks, the Guadiamar Green Corridor was established. Eight years after the mine accident (2005–2006), the ground-dwelling insectivorous lizard Psammodromus algirus registered high trace-element levels within the study area compared to specimens from a nearby unpolluted control site. In 2017, 20 years after the accident, we repeated the sampling for this lizard species and also quantified trace elements in vegetation as well as in arthropod samples in order to identify remnant trace-element accumulation with the aim of assessing the transfer of these elements through the trophic web. We found remnant trace-element contamination in organisms of the polluted site compared to those from the unpolluted site. All trace-element concentrations were higher in arthropods than in plants, suggesting these compounds bioaccumulate through the trophic web. Lizards from the polluted areas had higher As, Cd, and Hg concentrations than did individuals from the unpolluted area. Lizard abundance between sampling periods (2005–06 and 2017) did not vary in unpolluted transects but strongly declined at polluted ones. By contrast, the Normalized Difference Vegetation Index indicated that in the study period, the vegetation was similar at the two sampling sites. These results suggest that, 20 years after the accident, the trace-element pollution could be the cause of a severe demographic decline of the lizard in the polluted area.

Age structure of a lizard along an elevational gradient reveals nonlinear lifespan patterns with altitude.

Lifespan is one of the main components of life history. Shorter lifespans can be expected in marginal habitats. However, in the case of ectotherms, lifespan typically increases with altitude, even though temperature—one of the main factors to determine ectotherms’ life history—declines with elevation. This pattern can be explained by the fact that a shorter activity time favors survival. In this study, we analyzed how lifespan and other life-history traits of the lizard Psammodromus algirus vary along a 2,200 m elevational gradient in Sierra Nevada (SE Spain). Populations at intermediate altitudes (1,200–1,700 m), corresponding to the optimal habitat for this species, had the shortest lifespans, whereas populations inhabiting marginal habitats (at both low and at high altitudes) lived longest. Therefore, this lizard did not follow the typical pattern of ectotherms, as it also lived longer at the lower limit of its distribution, nor did it show a longer lifespan in areas with optimal habitats. These results might be explained by a complex combination of different gradients along the mountain, namely that activity time decreases with altitude whereas food availability increases. This could explain why lifespan was maximum at both high (limited activity time) and low (limited food availability) altitudes, resulting in similar lifespans in areas with contrasting environmental conditions. Our findings also indicated that reproductive investment and body condition increase with elevation, suggesting that alpine populations are locally adapted.

Crypsis Decreases with Elevation in a Lizard

Predation usually selects for visual crypsis, the colour matching between an animal and its background. Geographic co-variation between animal and background colourations is well known, but how crypsis varies along elevational gradients remains unknown. We predict that dorsal colouration in the lizard Psammodromus algirus should covary with the colour of bare soil—where this lizard is mainly found—along a 2200 m elevational gradient in Sierra Nevada (SE Spain). Moreover, we predict that crypsis should decrease with elevation for two reasons: (1) Predation pressure typically decreases with elevation, and (2) at high elevation, dorsal colouration is under conflicting selection for both crypsis and thermoregulation. By means of standardised photographies of the substratum and colourimetric measurements of lizard dorsal skin, we tested the colour matching between lizard dorsum and background. We found that, along the gradient, lizard dorsal colouration covaried with the colouration of bare soil, but not with other background elements where the lizard is rarely detected. Moreover, supporting our prediction, the degree of crypsis against bare soil decreased with elevation. Hence, our findings suggest local adaptation for crypsis in this lizard along an elevational gradient, but this local adaptation would be hindered at high elevations.

Increased individual homozygosity is correlated with low fitness in a fragmented lizard population

AbstractIsolation owing to anthropogenic habitat fragmentation is expected to increase the homozygosity of individuals, which might reduce their fitness as a result of inbreeding depression. Using samples from a fragmented population of the lizard Psammodromus algirus, for which we had data about two correlates of fitness, we genotyped individuals for six microsatellite loci that correctly capture genome-wide individual homozygosity of these lizards (as validated with an independent sample of lizards genotyped for both these microsatellites and > 70 000 single nucleotide polymorphisms). Our data revealed genetic structure at a very small geographical scale, which was compatible with restricted gene flow among populations disconnected in a matrix of inhospitable habitat. Lizards from the same fragment were genetically more related to one another than expected by chance, and individual homozygosity was greater in small than in large fragments. Within fragments, individual homozygosity was negatively associated with adult body size and clutch mass, revealing a link among reduced gene flow, increased homozygosity and lowered fitness that might reduce population viability deterministically. Our results contribute to mounting evidence of the impact of the loss of genetic diversity on fragmented wild populations.

Age Determination in the Sand Lizard Psammodromus algirus (Reptilia; Lacertidae) by Means of Skeletochronology

We examined lines of arrested growth (LAG) in femurs from 20 individuals of the sand lizard Psammodromus algirus sampled from the north of Tunisia (North Africa). The number of the LAGs reached a maximum of three. The instant speed of linear growth in the first year was 6.6×10–2 mm/day and 3.76×10–2 mm/day the second year. The diameter of the marrow cavity was significantly larger in female (334.52 µm±115.68 µm) than in male (324.42 µm±114.2 µm). The growth rate observed in P. algirus followed the known growth pattern in lacertid lizards and the difference in the diameter of the marrow cavity between males and females may be related to a sexual dimorphism.

Chemosensory discrimination of male age by female Psammodromus algirus lizards based on femoral secretions and feces

AbstractChemical communication plays an essential role in several social and reproductive behaviors of many animals. In lizards, the main sources of semiochemicals are femoral or pre‐anal gland secretions and feces. In male lizards Psammodromus algirus, there are age‐related differences in the chemical composition of femoral gland secretions and in the reproductive strategies, with older males defending territories and females, while younger males adopting sneak‐mating strategies. Females flee more often from mating advances of young males than from those of old males, which are more successful in obtaining matings. This suggests that age discrimination of males may be important for females. We tested here whether females showed differential chemosensory responses to chemical cues (femoral gland secretion and feces) of males of two age classes, and whether females use information from substrate scent marks of males of different ages to select where to stay. We found that females elicited more tongue‐flicks to the secretion and feces of old males than to control or secretion and feces of young males. Also, the time spent by females on a scented paper depended on the treatment, suggesting that females tended to spend more time on scent marks made with femoral secretions of old males. Adult females seemed capable to discriminate between young and old males based on chemical cues alone and showed more interest in scents of old males. However, substrate scent marks did not seem to entirely determine site selection by females, suggesting that females might need additional cues to perform the choice. These results can be explained by the different age‐dependent reproductive strategies of males, which can affect differentially to females.

Lizard calls convey honest information on body size and bite performance: a role in predator deterrence?

When encountering predators, prey animals often signal their ability to fight or flee to discourage the predator from an attack or pursuit. A key requirement for evolutionary stability of these predator-deterrent signals is that they convey honest information on the prey’s fighting or fleeing performance. In this study, we investigate the enigmatic ‘distress call’ of the lacertid lizard Psammodromus algirus, and test whether it conveys reliable information on an individual’s body size, and bite and sprint performance. Our acoustic analyses revealed a complex spectral structure in the vocalization of P. algirus, showing a wide frequency bandwidth, multiple harmonics, and a marked frequency modulation. This spectral design may allow such calls to be perceived by multiple potential predators, as it was assessed by a literature search comparing the call frequency range with the hearing ranges of P. algirus’ top predators. In addition, we found considerable inter-individual variation in the call design of lizards (‘call signatures’), which was linked with inter-individual variation in body size and maximum bite force, but not with sprint speed (a proxy of escape performance). As a whole, our study supports the hypothesis that the vocalizations of P. algirus lizards have the potential to serve as honest calls to deter predators. Further research on the behavioural response of predators towards lizard calls is essential in order to unravel the true predator deterrence potential of these calls. When eye-to-eye with a predator, prey animals may signal their ability to fight or flee to convince the predator not to attack or pursue them. Reptiles typically use visual displays to deter predators, but fascinatingly, Psammodromus algirus lizards have been observed to vocalize when encountered by predators. Here, we explored the acoustic properties of these calls and examined whether they convey honest information on a lizard’s fighting and fleeing performance. Our recordings indicate that the acoustic profile of the calls fall within the hearing sensitivity of the lizard’s top predators. Moreover, our experiments show a significant link between the acoustic profile of lizard calls and lizard fighting ability, but not with fleeing ability. Together, our results imply that these lizard calls have predator deterrence potential. Additionally, this study provides the first evidence of honest acoustic signalling of performance in a reptile.

Habitat type influences parasite load in Algerian Psammodromus (Psammodromus algirus) lizards

Understanding how habitat type and deterioration may affect parasitism is important in assessing the effects of human-induced environmental change on host–parasite dynamics. In this study, we examined inter-population differences in parasite load in the Mediterranean lizard Psammodromus algirus (Linnaeus, 1758). We analyzed prevalence and intensity of infection by blood parasites and ectoparasites in two populations separated by a 400 m elevational gradient and with different habitat types that also differed in the degree of human alteration. We also compared data obtained from the same populations 10 years later to assess whether there have been temporary changes in parasite loads. Results showed that prevalence and intensity of blood parasites were higher in the deteriorated lowland holm oak forest population than in the well-preserved upland oak forest. In contrast, the prevalence and intensity of infection by Ixodes Latreille, 1795 ticks was higher in the upland oak forest population. Individuals from the lowland population were in poorer condition. Intensities of infection by blood parasites and ectoparasites have decreased significantly from 2005–2006 to 2016 in both populations. Our results suggest that inter-population differences in parasite load may be explained by differences in habitat characteristics. This study contributes to the identification of ecosystems and habitats that are most sensitive to prevalence and intensity of infection by parasites.

Drivers of Psammodromus algirus abundance in a Mediterranean agroforestry landscape

Mediterranean European landscapes have been shaped by human activities for centuries, particularly by livestock and farming. Traditionally managed montado landscapes have been recognized as having a crucial role in biodiversity conservation, providing habitat complexity and thus, ecological conditions for a variety of species. Biodiversity associated with montado can only be maintained under specific agricultural practices, with the intensification or abandonment of such practices posing serious threats for wildlife. Despite the high number of reptile species endemic to the Iberian Peninsula, research on the influence of agroforestry management practices on these species has been scarce. The mediterranean lizard Psammodromus algirus is a generalist species that responds to changes in the structure and quality of microhabitats, specifically the shrub layer, which is greatly affects by changes in cattle grazing intensity. In this study, we assessed how grazing affects the frequency of occurrence of P. algirus in a Mediterranean landscape dominated by montado. We detected that areas of intermediate age regarding grazing exclusion support higher lizard abundance, with P. algirus abundance being limited by vegetation structure and solar radiation. Thus, we may infer that the vegetation structure regulatory role of cattle will affect this lizard’s abundance, limiting it indirectly. We suggest that the maintenance of adequate traditional management, allowing the grazing pressure at low to moderate levels, would be beneficial to this species and reptiles in general and conclude that reconciling grazing and reptile conservation is possible if done in a sustainable way.

Prey availability, prey selection, and trophic niche width in the lizard Psammodromus algirus along an elevational gradient.

Mountains imply enormous environmental variation, with alpine habitats entailing harsh environments, especially for ectotherms such as lizards. This environmental variability also may imply variation in prey availability. However, little is known about how lizard trophic ecology varies with elevation. In this study, we analyze diet, prey availability, prey selection, and trophic niche width in the lacertid lizard Psammodromus algirus along a 2,200-m elevational gradient in the Sierra Nevada (SE Spain). The analysis of fecal samples has shown that Orthoptera, Formicidae, Hemiptera, Coleoptera, and Araneae are the main prey, although, according to their abundance in pitfall traps, Formicidae and Coleoptera are rejected by the lizard whereas Orthoptera, Hemiptera, and Araneae are preferred. Prey abundance and diversity increase with elevation and diet subtly varies along with the elevational gradient. The consumption of Coleoptera increases with elevation probably as a consequence of the lizard foraging more in open areas while basking. The electivity for Araneae increases with elevation. Araneae are rejected in the lowlands—where they are relatively abundant—whereas, at high elevation, this lizard positively selects them, despite they being less abundant. The lizard trophic niche width expands with elevation due to concomitant greater prey diversity and hence this lizard feeds on more prey types in highlands. Although no sex difference in diet has been found, the trophic niche is broader in females than males. As a whole, alpine lizards show a trophic niche similar to that found at lower elevations, suggesting that P. algirus is well adapted to the harsh environment found in alpine areas.

Expression of regulatory genes in the embryonic brain of a lizard and implications for understanding pallial organization and evolution.

The comparison of gene expression patterns in the embryonic brain of mouse and chicken is being essential for understanding pallial organization. However, the scarcity of gene expression data in reptiles, crucial for understanding evolution, makes it difficult to identify homologues of pallial divisions in different amniotes. We cloned and analyzed the expression of the genes Emx1, Lhx2, Lhx9, and Tbr1 in the embryonic telencephalon of the lacertid lizard Psammodromus algirus. The comparative expression patterns of these genes, critical for pallial development, are better understood when using a recently proposed six‐part model of pallial divisions. The lizard medial pallium, expressing all genes, includes the medial and dorsomedial cortices, and the majority of the dorsal cortex, except the region of the lateral cortical superposition. The latter is rich in Lhx9 expression, being excluded as a candidate of dorsal or lateral pallia, and may belong to a distinct dorsolateral pallium, which extends from rostral to caudal levels. Thus, the neocortex homolog cannot be found in the classical reptilian dorsal cortex, but perhaps in a small Emx1‐expressing/Lhx9‐negative area at the front of the telencephalon, resembling the avian hyperpallium. The ventral pallium, expressing Lhx9, but not Emx1, gives rise to the dorsal ventricular ridge and appears comparable to the avian nidopallium. We also identified a distinct ventrocaudal pallial sector comparable to the avian arcopallium and to part of the mammalian pallial amygdala. These data open new venues for understanding the organization and evolution of the pallium.