Podarcis Hispanica Research Articles

Comparing patterns of nuclear and mitochondrial divergence in a cryptic species complex: the case of Iberian and North African wall lizards (Podarcis, Lacertidae)

Combining different sources of information is essential for a complete understanding of the process of genetic differentiation between species. The Iberian and North African wall lizard (Podarcis) species complex has been the object of several studies regarding morphological and mitochondrial DNA variation but, so far, no large-scale survey of nuclear variation within this group has been accomplished. In this study, ten polymorphic allozyme loci were studied in 569 individuals collected across the Iberian Peninsula and North Africa. The obtained data were analysed using both conventional population genetic tools and recent Bayesian model-based clustering methods. Our results show that there are several well-differentiated entities corroborating the major splits observed in mtDNA analyses. These groups correspond not only to the fully recognized species Podarcis bocagei, Podarcis carbonelli, and Podarcis vaucheri but also to multiple forms within the polytypic Podarcis hispanica, all of which have a similar level of differentiation to that observed between the acknowledged species. However, relationships between forms are weakly supported both by population and individual clustering methods, suggesting a scenario of a rapid diversification that contrasts to the clear bifurcating model assumed from previous mtDNA analyses. Individual multilocus analyses report few individuals misassigned or apparently admixed, some of which are most likely explained by the persistence of high levels of ancestral polymorphism. Other admixed individuals, however, are probably the result of limited levels of gene flow between forms. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 121–133.

Effects of testosterone supplementation on chemical signals of male Iberian wall lizards: consequences for female mate choice

In some lizards, female mate choice is influenced by chemicals secreted by males, e.g., via the femoral glands. Secretions of the femoral glands are under direct androgenic control and vary seasonally with androgen production. However, whether increased testosterone (T) levels affect the concentration and chemical composition of secretions or their attractiveness to females is unknown. We manipulated T levels of male Iberian wall lizards, Podarcis hispanica, with silastic implants. Differential tongue-flick rates indicated that females detected and discriminated between femoral secretions of control and T-implanted males based on chemical cues alone. Females showed greater responses to secretions of T-males, which might suggest that T increased the concentration of chemical signals. Further analyses by gas chromatography–mass spectrometry indicated that T supplementation induced qualitative changes in lipid composition of femoral secretions. T-males had decreased relative proportions of cholesta-5,7-dien-3-ol in secretions, which might be related to the negative effects of T on the immune system and on lipid metabolism. However, experiments of choice of males’ scent showed that females neither preferred nor avoided the scent marks of T-males but preferred males that maintained higher proportions of cholesta-5,7-dien-3-ol in secretions, independently of the experimental manipulation. Thus, because this steroid is negatively affected by T, there might be trade-offs among increasing T levels to increase the production of chemical secretions, maintain metabolism, and attract females.

Chemosensory Responses by Female Iberian Wall Lizards, Podarcis Hispanica to Selected Lipids Found in Femoral Gland Secretions of Males

In many lizards, secretions of males are used in social behaviors, but it is almost unknown which specific chemicals are relevant in mediating these behaviors. Moreover, only a few studies have examined whether lizards can actually discriminate between different chemical compounds. We tested for differential chemosensory responses of female Iberian Wall Lizards, Podarcis hispanica, to two lipids (cholesterol and cholesta-5,7-dien-3-ol) found in femoral secretion of males, and which previous behavioral studies suggested may be relevant in female mate choice. The higher tongue-flick (TF) rates directed at cotton swabs containing these two lipids indicated that females detected and discriminated these chemicals from a control. There were no significant differences between responses to cholesterol and to the whole natural femoral secretion from males, probably because cholesterol is the major predominant component in secretions of males. The higher TF rates to cholesta-5,7-dien-3-ol than to cholesterol indicated that females discriminated these two steroids. Moreover, females seemed able to assess changes in concentration of cholesta-5,7-dien-3-ol and responded more strongly to higher concentrations. These results, together with the previous finding of female preference for areas scent marked by males with higher proportions of this steroid in their secretions, might support that cholesta-5,7-dien-3-ol was a “key” chemical that might be used by females to choose potential mates.

Natural oak forest vs. ancient pine plantations: lizard microhabitat use may explain the effects of ancient reforestations on distribution and conservation of Iberian lizards

Natural vegetation in Europe appears nowadays deeply modified by human activities. In the Guadarrama Mountains (Central Spain), ancient reforestations with Scots pines, Pinus sylvestris, replaced original deciduous pyrenean oak, Quercus pyrenaica, forests (since the Roman period). However, the effect of reforestations on fauna remains little known, especially in reptiles. We described patterns of microhabitat selection in several species of Lacertid lizards, and analyzed whether the modification of the original vegetation affected distribution and population densities of lizards. The species of lacertid lizards found in oak forests (Psammodromus algirus, Lacerta lepida and Podarcis hispanica) were different to those of in pine plantations (Podarcis muralis and Podarcis hispanica). Lizards did not use habitat at random and this could explain differences in species found in both forests, which differed in some microhabitat structure characteristics. Most lizards selected microhabitats with rocky outcrops, with low cover of trees, and close to refuges. These microhabitat preferences also explained abundance of lizards in transects. From the perspective of conservation and management of lizards, pine plantations seem not to contribute too much to the diversity of lizard species because species typical from oak forests were lost. This study has implications for pine reforestation management, because allowing the recolonization by understory oaks, and leaving some open areas, without trees but with dense shrubs and rocks inside reforestations would contributed to maintain lizard populations.

Interpopulational differences in chemical composition and chemosensory recognition of femoral gland secretions of male lizards Podarcis hispanica: implications for sexual isolation in a species complex

Molecular studies suggest that the Iberian wall lizard, Podarcis hispanica, forms a species complex with several monophyletic types. In Central Spain two of these types are spatially not isolated and may interact. Sex pheromones are important for species recognition and, thus, differences between lizards’ types in chemicals used in intraspecific communication could lead to reproductive isolation. Analyses by GC-MS showed that the femoral gland secretions of adult males of different types were different. Males of one type had twelve exclusive compounds, and proportions of some shared compounds differed. This presumably would reflect selection for the persistency and efficiency of chemical signals in different environments; less volatile compounds and with a higher chemical stability being favoured in the type of lizards inhabiting more humid climatic conditions. Differential tongue-flick rates to scents from femoral secretions indicated that males were able to detect and discriminate between males of different types based on chemical cues alone. In contrast, females detected but did not seem able to discriminate between scents of the two types of males. Thus, multiple factors might be simultaneously acting either against or in favor of speciation, leading, on the one hand, to genetic differences between types, but, on the other hand, probably precluding an effective reproductive isolation in areas where both types of lizards may interact.

Female Iberian wall lizards prefer male scents that signal a better cell-mediated immune response

In spite of the importance of chemoreception in sexual selection of lizards, only a few studies have examined the composition of chemical signals, and it is unknown whether and how chemicals provide honest information. Chemical signals might be honest if there were a trade-off between sexual advertisement and the immune system. Here, we show that proportions of cholesta-5,7-dien-3-ol in femoral secretions of male Iberian wall lizards (Podarcis hispanica) were related to their T-cell-mediated immune response. Thus, only males with a good immune system may allocate higher amounts of this chemical to signalling. Furthermore, females selected scents of males with higher proportions of cholesta-5,7-dien-3-ol and lower proportions of cholesterol. Thus, females might base their mate choice on the males' quality as indicated by the composition of their chemical signals.

Amygdalostriatal projections in reptiles: a tract-tracing study in the lizard Podarcis hispanica.

Whereas the lacertilian anterior dorsal ventricular ridge contains unimodal sensory areas, its posterior part (PDVR) is an associative center that projects to the hypothalamus, thus being comparable to the amygdaloid formation. To further understand the organization of the reptilian cerebral hemispheres, we have used anterograde and retrograde tracing techniques to study the projections from the PDVR and adjoining areas (dorsolateral amygdala, DLA; deep lateral cortex, dLC; nucleus sphericus, NS) to the striatum in the lizard Podarcis hispanica. This information is complemented with a detailed description of the organization of the basal telencephalon of Podarcis. The caudal aspect of the dorsal ventricular ridge projects nontopographically mainly (but not exclusively) to the ventral striatum. The NS projects bilaterally (with strong ipsilateral dominance) to the nucleus accumbens, thus recalling the posteromedial cortical amygdala of mammals. The PDVR (especially its lateral aspect) and the dLC project massively to a continuum of structures connecting the striatoamygdaloid transition area (SAT) and the nucleus accumbens (rostrally), the projection arising from the dLC being probably bilateral. Finally, the DLA projects massively and bilaterally to both the ventral and dorsal striatum, including the SAT. Our findings lend further support to the view that the PDVR and neighboring structures constitute the reptilian basolateral amygdala and indicate that an emotional brain was already present in the ancestral amniote. These results are important to understand the comparative significance of the caudal aspect of the amniote cerebral hemispheres, and specifically challenge current views on the nature of the avian caudal neostriatum.

Ease and effectiveness of costly autotomy vary with predation intensity among lizard populations

AbstractCostly anti‐predatory defences are used in ecological time and maintained in evolutionary time by natural selection favouring individuals that survive through their use. Autotomy of expendable body parts is a striking example of a defence having multiple substantial costs, including loss of ability to use the same defence, loss of energy, and decreased growth, reproductive success and survival following autotomy, plus the energetic cost of replacing the lost body part in species capable of regenerating them. Our study shows that autotomy in the lacertid lizard Podarcis lilfordi reduces sprint speed, indicating decreased capacity to escape as well as the loss of energy. Autotomy carries substantial cost, and thus should be avoided except as a last resort. Ease of autotomy and post‐autotomic movements were studied in three populations of lacertid lizards. Two were islet populations of P. lilfordi from Aire (lowest predation pressure) and Colom (intermediate predation pressure) off Minorca. The third was a mainland population of Podarcis hispanica, a closely related species from the mainland of the Iberian Peninsula where predation pressure is higher than on the islets. As predicted, a suite of autotomic traits increases the effectiveness of autotomy as a defence as predation pressure increases. With increasing predation pressure, the frequency of voluntary autotomy increases, latency to autotomy decreases, pressure on the tail needed to induce autotomy decreases, vigour of post‐autotomic tail movements increases, and distance moved by the shed tail increases. Additional changes that might be related to predation pressure, but could have other causes, are the presence of tail coloration contrasting with body coloration except under the lowest predation pressure (Aire) and longer tails in the mainland species P. hispanica. Correspondence between predation pressure and the suite of autotomic traits suggests that autotomy is an important defence that responds to natural selection. Comparative data are needed to establish the generality of relationships suggested in our study of only three populations.

Reproductive Characteristics of an Insular Population of the Lizard Podarcis hispanica from Northwest Spain (Cíes Islands, Galicia)

Abstract Here I report on the reproductive characteristics of an insular population of the lacertid lizard Podarcis hispanica, which inhabits the Cies Islands, an archipelago formed by three small islands off the northwest coast of Spain. The clutch characteristics of the population were investigated on the basis of clutches laid by pregnant females captured on these islands in 1999 and 2000. Other data were obtained principally by mark-recapture experiments. The egg-laying cycle of live females was determined by ventral palpation. Enlarged follicles were detected from March to July, and the laying period extended from April to the second half of July. The larger females initiated reproductive activities early in the season and produced up to three clutches annually, whereas the smaller individuals laid only a single clutch. Reproductive performance was related mainly to female size. Clutch size, individual egg mass, clutch mass, and hatchling size increased with the length of the females. I also examined...

Stimulus control of predatory behavior by the Iberian wall lizard (Podarcis hispanica, Sauria, Lacertidae): effects of familiarity with prey.

The authors examine the relative roles of vision and chemoreception and the influence of previous experience with prey on the predatory behavior of Iberian wall lizards (Podarcis hispanica). Experiment 1 compared the responses to visual, chemical, and a combination of visual and chemical cues of a familiar prey by 2 groups of lizards that had been kept in captivity for either 3 months or 21 days. Experiment 2 assessed the responses of lizards kept in the laboratory for more than 3 months to a novel prey species. The results reveal that feeding on a prey species affects the lizards' responses to chemical stimuli from that prey. The response to chemical cues of a novel prey requires a 1st-feeding experience with that prey. Lizards that have been fed the same prey species for several months cease responding to the chemical stimuli of that particular prey.

CRMP-4 expression in the adult cerebral cortex and other telencephalic areas of the lizard Podarcis hispanica

The control of neuritogenesis is crucial for the development, maturation and regeneration of the nervous system. The collapsin response-mediated protein 4 (CRMP-4) is a member of a family of proteins that are involved in neuronal differentiation and axonal outgrowth. In rodents, this protein is expressed in recently generated neurons such as some granule neurons of the dentate gyrus, as well as in certain differentiated neurons undergoing neurite outgrowth or synaptogenesis during adulthood. Since CRMP-4 protein appears to be highly conserved throughout the evolutionary scale, we have used immunocytochemistry to study its distribution in the lizard cerebral cortex. We have found pronounced CRMP-4 immunolabeling in certain neurons of the medial cortex, the homologous region to the dentate gyrus, but also in the dorsal and lateral cortices. Double labeling with 5′-BrdU indicated that these medial cortex neurons were recently generated. However, it is also possible that many of these cells were not new but undergoing some kind of plasticity implicating neurite outgrowth. Similar CRMP-4-labeled neurons and processes were observed in subcortical regions as the PDVR and the nucleus sphericus. Our results show for the first time the expression of CRMP-4 in a reptile brain, where it appears to be expressed in regions where adult neurogenesis and/or neurite outgrowth occur.

Complex biogeographical distribution of genetic variation within Podarcis wall lizards across the Strait of Gibraltar

Abstract Aim To examine the effect of a known geological barrier on genetic variation within a wall lizard species complex.Location The Iberian Peninsula and North Africa.Methods Sequencing of partial 12S rRNA and cytochrome b mtDNA.Results The current distribution of genetic variability is not related to the opening of the Strait of Gibraltar.Conclusions Podarcis hispanica in North Africa is probably a species complex. The Strait of Gibraltar should not be used as a known barrier to gene flow in other land based organisms without careful sampling to test for multiple crossings since its formation.

The effect of Mediterranean dehesa management on lizard distribution and conservation

Management of dehesas (i.e. oak woodland pastures) creates a patchwork of sectors that differ in their structure and composition of understorey vegetation. We analysed whether different management techniques affect the populations of several species of lizards ( Podarcis hispanica, Psammodromus algirus, Psammodromus hispanicus, Acanthodactylus erythrurus, and Lacerta lepida). Multivariate analyses showed that lizards preferentially used forested areas with scrub while they avoided open herbaceous areas. The abundance of lizards increased when the understorey bushy vegetation increased. In contrast, grasslands or cereal fields were scarcely occupied even if holm oak trees ( Quercus ilex) were present, apparently because low shrubs were scarce here. Therefore, some of the traditional management practices of dehesas may negatively affect lizard populations. These conclusions could have wider implications for the design of wildlife reserves within dehesas, which has been previously based on the umbrella species concept (e.g. some dehesas are managed for imperial eagle Aquila adalberti conservation), without considering habitat requirements of other representative animal groups.

Distribution of calcitonin gene-related peptide-like immunoreactivity in the brain of the lizard Podarcis hispanica.

The present work studies the distribution of calcitonin gene-related peptide-immunoreactive (CGRP-li) neurons and fibers in the brain of a reptile, the lizard Podarcis hispanica. CGRP-li perikarya were not present in the telencephalon. In the thalamus, CGRP-li perikarya were restricted to the posteromedial and posterolateral nuclei. In the hypothalamus, CGRP-li cells were found mainly in the supramammillary and mammillary nuclei. In the midbrain and brainstem, CGRP-li cells appeared in the ventral tegmental area, the parabrachial nucleus, and the motor nuclei of the III-VII, IX, X, and XII cranial nerves. Motoneurons of the ventral horn of the spinal cord were also immunoreactive for CGRP. CGRP-li fibers were seen in the telencephalic hemispheres, where a dense plexus of reactive fibers appeared in the septum and in the lateral striatoamygdaloid transition area. From the latter, CGRP-li fibers entered the posterior dorsal ventricular ridge, the cell layer and deep stratum of the ventral lateral cortex, and various amygdaloid nuclei. Parts of the striatum (nucleus accumbens) and pallidum also displayed CGRP-li innervation. In the diencephalon, CGRP-li innervation was observed in parts of the dorsal thalamus and in the periventricular and medial hypothalamus. The pretectum and deep layers of the optic tectum also showed CGRP-li fibers, and numerous CGRP-li fibers were observed in the midbrain central gray, tegmentum, and pons. Some of the sensory fibers of the trigeminal, vagal, and spinal nerves were also CGRP-li. These results show that the distribution of CGRP-li structures in the reptilian brain is similar to that described for other vertebrates and suggest that the thalamotelencephalic CGRPergic projections appear to be conserved among amniote vertebrates.

Pheromonal discriminations of sex, reproductive condition, and species by the lacertid lizard Podarcis hispanica.

In some vertebrate taxa, pheromones provide important information about species, sex, reproductive condition, kinship, and even individual identity. Because they possess highly developed nasal chemosensory systems, lizards are capable of many chemical discriminations, but many aspects of their pheromonal communication remain poorly understood even in major families. We report that males of a lacertid lizard, Podarcis muralis, are capable of differential response to surface chemical cues from conspecific males and females, from gravid and nongravid females, and from conspecific females and females of the closely related sympatric congener, P. bocagei carbonelli. In 60 sec trials in which stimuli from the femoral, cloacal, lateral, and upper body surfaces were presented to males on cotton swabs, males tongue-flicked at significantly higher rates to stimuli from conspecific females than males, from conspecific nongravid than gravid females, and from conspecific than heterospecific females. Responses to stimuli from conspecific males did not differ from those to distilled water. Together with previous findings that males can distinguish between chemical cues from familiar and unfamiliar males, these findings suggest that pheromones provide male P. hispanica important information regarding the presence of sexual rivals and the reproductive condition of potential mates without visually encountering other lizards. A growing body of literature indicates that lacertids are capable of sophisticated pheromonal discriminations that may play important roles in their social behavior.

Chemical rival recognition decreases aggression levels in male Iberian wall lizards, Podarcis hispanica

In an agonistic interaction, the assessment of the probable outcome of future encounters with the same individuals may be the best way of decreasing costs of fighting, but this may only be accomplished if animals are able to recognize individual conspecifics. We staged encounters between male lizards, Podarcis hispanica, to examine whether odoriferous cues are involved in rival recognition during agonistic interactions. We experimentally manipulated the odour of intruding males, creating familiar males with their own odour or bearing odours of unfamiliar males, and unfamiliar males bearing unfamiliar odours or odours of familiar males. The results showed that when familiar males were impregnated with scents from unfamiliar males, they elicited an aggressive response by resident unmanipulated males similar to that observed for a new unfamiliar male with unfamiliar odour. This suggests that resident males were unable to recognize familiar males when their own scents were removed. In contrast, responding males were less aggressive towards familiar males impregnated with their own odour and towards unfamiliar males impregnated with scents of familiar males, suggesting that when two males have already interacted, their scents become familiar for both males, and that the detection in successive encounters of the familiar scent suffices to reduce the aggressive response of territorial males. Therefore, recognition mechanisms based on chemical cues during agonistic encounters may contribute to reducing the intensity and the costs of fighting in P. hispanica and may play an important role in the organization of their social system.

Chemosensory Recognition of Familiar and Unfamiliar Conspecifics by Juveniles of the Iberian Wall Lizard Podarcis hispanica

Chemosensory recognition of familiar conspecifics has been reported in studies with members of several lizard families and may be advantageous to distinguish between intruders and neighbors or group members. However, few species have been studied and information on the ability to discriminate between familiar and unfamiliar conspecifics by chemosensory means is lacking for most lizard families. In this paper we ask whether juveniles of the Iberian wall lizard Podarcis hispanica (Lacertidae), can discriminate between chemical signals from familiar conspecifics with whom they have shared a terrarium for several months and those from unfamiliar conspecifics housed in a different terrarium. Experimental trials were conducted by transferring juveniles to a test terrarium with a filter paper substrate. We tested the responses of lizards to paper substrates labeled by familiar cage‐mates, unfamiliar conspecifics, or unlabeled. Tongue‐flicks and other behaviors in response to pheromonal stimuli were recorded for 10 min Juveniles directed more chemosensory behavior towards paper substrates bearing chemicals from familiar conspecifics than towards similar paper substrates labeled by unfamiliar conspecifics. These results indicate that juveniles in this lizard species can recognize familiar conspecifics and discriminate between familiar and unfamiliar individuals using only chemical stimuli. We discuss the role of habituation in familiar conspecific recognition and review possible explanations of the functional significance of this type of discrimination in lizards.

Molecular Phylogenetics of Iberian Wall Lizards (Podarcis): Is Podarcis hispanica a Species Complex?

Phylogenetic relationships between species and morphotypes of Podarcis wall lizards from the Iberian Peninsula and north Africa were estimated using partial 12S rRNA and cytochrome b mitochondrial DNA sequences. All species except Podarcis hispanica form monophyletic units. P. hispanica is paraphyletic, although all identified morphotypes are monophyletic. These morphotypes represent highly divergent lineages showing 10–15% pairwise sequence divergence with the cytochrome b gene. The data suggest that P. hispanica is a species complex. We recommend using P. hispanica* until additional sampling delimits the number and ranges of species currently referred to P. hispanica. P. carbonelli, which has recently been raised to species status, is confirmed as a genetically distinct form. P. atrata is genetically distinct, but much more closely related to some populations of P. hispanica than previously thought.

Afferent and efferent projections of the dorsal anterior thalamic nuclei in the lizard Podarcis hispanica (Sauria, Lacertidae)

The aim of this study was to investigate the afferent and efferent connections of the anterior thalamic nuclei in the lizard Podarcis hispanica. To identify potential sources of sensory inputs and to determine the fine organization of the projections of these thalamic nuclei to the telencephalon, we injected the sensitive tracer biotinylated dextran amine (BDA) into different nuclei of the anterior dorsal thalamus. We also injected BDA into several telencephalic areas in order to corroborate the results of thalamic injections. Our results show that the anterior thalamic nuclei receive projections from multiple areas and nuclei distributed throughout most of the brain, from rhombencephalon to telencephalon, and project to several telencephalic areas. The nucleus dorsolateralis anterior receives somatic (visual, somatosensory, auditory) as well as visceral inputs, and it is thus an important gateway for the relay of multisensory information to the telencephalon.

Striato-amygdaloid transition area lesions reduce the duration of tonic immobility in the lizard Podarcis hispanica

Neuroanatomical data suggest that the lizard striato-amygdaloid transition area is homologous with the mammalian central amygdala. In order to investigate possible functional similarities, tonic immobility was induced in adult lizards and its duration recorded. Each lizard was then randomly assigned to one of three treatments: (1) bilateral striato-amygdaloid transition area lesions, (2) bilateral dorsal cortex lesions or (3) untreated controls. Three days after trial 1, each lizard was subjected to a second trial and the tonic immobility duration recorded. The mean tonic immobility duration in lizards with striato-amygdaloid transition area lesions was significantly shorter (80.5%; p < 0.0033) in trial 2 than in trial 1. There were no inter-trial differences within dorsal cortex-lesioned lizards or untreated controls. There was a significant treatment effect on tonic immobility duration in trial 2 ( p < 0.0001). The mean tonic immobility duration of lizards with striato-amygdaloid transition area lesions was significantly shorter than that of dorsal cortex-lesioned lizards (72.2%; p < 0.01) or untreated controls (78.2%; p < 0.01). There was no significant difference in mean tonic immobility duration between dorsal cortex-lesioned lizards and untreated controls. Tonic immobility is considered to be an anti-predator behaviour that reflects the underlying state of fear. Therefore, the reduced tonic immobility duration in lizards with striato-amygdaloid transition area lesions reflects a reduction of fear. These results provide the first data to indicate a functional similarity between the lizard striato-amygdaloid transition area and the mammalian central amygdala.