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Reportamos la primera evidencia que sugiere que el lagarto Liolaemus torresi podría consumir al insecto nativo, la polilla esfinge Hyles annei.

Escaping from predation saves life, but costs energy and time. The “threat-sensitive predator-avoidance” hypothesis proposes that prey may modulate their antipredator responses, and thus the associated costs, in accordance with the magnitude of predation risk. This process requires that prey accurately assess this risk by decoding available information from various sources. For example, distress calls are uttered by prey when a predator traps them and can serve as public information on predation risk. Such is the case for the weeping lizard whose distress calls trigger immobility in conspecifics. Here, we tested whether this antipredator response of the weeping lizard is modulated by witnessing predation. We exposed lizards to distress calls alone or paired with models of a prey (conspecific), a predator (snake), or a predatory event (a snake subjugating the conspecific). Data show that the sole presence of the predator or prey paired with distress calls seems not to modulate the antipredator responses. Contrarily, witnessing a predatory event associated with calls intensified antipredator responses; lizards reduced their activity for longer and avoided proximity to the stimuli, which may decrease predation risk by reducing the likelihood of being detected by the predator. We conclude that the weeping lizard can use multisensorial public information to assess predation risk and modulate its antipredator responses.

Reproductive isolating barriers are a crucial element in the speciation process. There are various types of barriers, and within those that act early in the speciation process, the behavioral one can play an important role in isolating populations or closely related species. It has been shown that the high diversity of some taxa correlates with the variation of sexual signals, which facilitate isolation. Here it is explored whether chemical signals may contribute to the high diversity of Liolaemus lizards, which has more than 290 species. Population chemical discrimination was investigated in two co-distributed species, L. tenuis and L. lemniscatus. The studied populations were closely located and likely belonged to the same genetic lineages. Lizards of both species discriminated between scents of their own and different populations, and in most cases, scents from their population were preferred. Results suggest a fast evolution of scents, and their recognition, and there for the ethological barriers associated with the chemical modality may evolve fast. However, because the studied species differed in the strength of the exhibited population chemical discrimination, ethological barriers evolve at different rates across species. It can be concluded that ethological barriers involving the chemical modality may disrupt species' cohesion, contributing to Liolaemus diversification, in synergy or not with geographical barriers.

Vertebrate predation by invertebrates has been classically underexplored and thus underestimated, despite the fact that many arthropods consume vertebrates. To shed some light on the relevance that spider predation may have upon lizards in the Neotropical and Andean regions, we compiled the available information in the literature on this trophic interaction. We found 50 reports of spiders consuming lizards in these regions, and the 88% of these were from the Neotropical region. Spiders belong to eight families, but Ctenidae and Theraphosidae were the most frequently reported predators. Lizards belong to 12 families, and the most commonly consumed species corresponded to the families Dactyloidae (all Anolis lizards), Gymnophthalmidae, and Sphaerodactylidae. Data suggest trophic spider–lizard associations between Ctenidae and Dactyloidae, followed by Theraphosidae and Liolaemidae. The body sizes of the spiders and lizards showed a positive relationship, and spiders were smaller than their prey. We conclude that various spider taxa can be considered lizard predators and they may be ecologically important in the Neotropical and Andean regions. However, spiders of prime predation relevance seem to be those of the Ctenidae and Theraphosidae families., In this study, we analyze for the first time the lizard consumption by spiders in the Neotropical and Andean regions, showing that the families Ctenidae and Theraphosidae may be relevant lizard predators in these areas. In addition, we provide the first report on spider predation upon a vertebrate taxon in the Andean region.

For a prey, its best ticket to stay alive is to get early and accurate information on predation risk and so, escape from predation at low cost. Some prey species have evolved the ability to eavesdrop signals intended for others, which contain information on predation risk. This is the case for the vocalizations produced by prey species when interacting with predators. Although primarily studied in birds and mammals, eavesdropping on vocal signals has been recorded in some lizard species. Here, we explored whether the lizard Liolaemus lemniscatus eavesdrops on the distress calls of its sympatric species, the Weeping lizard (L. chiliensis). Individuals of the Weeping lizard respond to these calls by displaying antipredator behaviours (i.e., reduced movement), and individuals of L. lemniscatus may potentially display similar defences if they decode the information contained in these calls. Our playback experiments showed that individuals of L. lemniscatus responded to the sound stimuli (distress calls and white noise), reducing their activity, but they did not discriminate between these two stimuli, suggesting that L. lemniscatus does not eavesdrop on the distress calls of its sympatric lizard species. We discuss some hypotheses to explain the lack of eavesdropping by L. lemniscatus on the Weeping lizard distress calls.

Few studies on song learning have been conducted in the field. Male pied flycatchers (Ficedula hypoleuca) seem to learn song syllables in the breeding grounds. Adult males arrive first to the breeding grounds and sing more complex songs until they have paired. Early arriving juveniles may have more opportunities to learn new syllables from adult neighbours and develop more complex songs than later arriving juveniles. However, results suggest that arrival time is not important in song complexity development, but that males develop greater song complexity (repertoire size and song versatility) regardless as they age.

Among amphibians, conspecific chemical communication has been widely studied in Caudata. Adult anurans, by contrast, have received less attention. Recently, it was shown that chemical scents are also relevant for adult anuran intraspecific communication. In this context, we evaluate whether females of the four-eyed frog (Pleurodema thaul) respond to conspecific male scents. We carried out a double choice experiment in a Y-maze. Females were repeatedly presented with the scents of several males versus distilled water. To extract the scent from males, we acoustically stimulated males and then used the water from their aquaria for the experiments. Our data suggest that females are capable of responding behaviourally to male scents, since they spent longer periods in the zones with male scent, rather than in zones with water. We propose that under natural breeding conditions, females of P. thaul may use either their chemical sense or chemical cues to facilitate their encounters with males.

Pheromones, a mix of proteins and lipids, are involved in lizards' conspecific recognition. In our study, we specifically address whether fecal lipids are involved in conspecific recognition of the Weeping Lizard, Liolaemus chiliensis. The feces of each sex were dissolved in n-hexane to isolate their lipidic fraction. We then exposed individuals of both sexes of L. chiliensis to the lipidic fractions of each sex and a control (n-hexane), recording their responses. Lizards of both sexes were more active when exposed to the lipids from male than from female feces or from the control, suggesting that the lipidic fraction of male feces conveys some information for conspecific recognition. There was, however, no further evidence of recognition, and herein we offer possible explanations for this low responsiveness to the fecal lipidic fractions.

Some lizard species modulate the use of a retreat site based on the presence of scents from other individuals, behavior that requires scent recognition. Here, we investigated if two congeneric and syntopic lizards (adults of Liolaemus coeruleus and juveniles of L. ceii, which can be found sharing retreat sites in the wild) discriminate scents from each other during the pre-hibernation period. If the presence of heterospecific scents modulates sharing retreat sites, species would discriminate each other’s scents. Lizards were individually exposed to four treatments, which were enclosures with scents of (1) from the focal individual (own); (2) a conspecific of the same sex as the focal lizard; (3) a heterospecific of the same sex as the focal lizard; and (4) a control (i.e., enclosure with a clean substrate). Our results suggest that there is no heterospecific recognition. This finding was not due to an inability to chemo-assess scents, since both species exhibited self-recognition (recognition of their own scents) and juveniles of L. ceii also showed conspecific recognition. Although it might be advantageous for species to share retreat sites, chemical recognition of heterospecific scents does not modulate this behavior in these syntopic species. Algunas especies de lagartos modulan el uso de un sitio de retiro basados en la presencia de rastros de olores de otros individuos presentes en el sitio, comportamiento que requiere reconocimiento de estos rastros de olores. En este trabajo, investigamos dos lagartos cogenéricos y sintópicos (adultos de Liolaemus coeruleus y juveniles de L. ceii, los cuales pueden ser encontrados en la naturaleza compartiendo sitios de retiro), si discriminan los rastros de olores de cada uno de ellos durante el periodo pre-invernal. Si la presencia de rastros de olores heteroespecíficos modula el compartir sitios de retiro, ambas especies discriminarían los rastros de olores entre sí. Los lagartos fueron expuestos individualmente a cuatro tratamientos, los cuales fueron los recintos con diferentes olores de: (1) propio, del individuo focal; (2) conespecífico del mismo sexo que el lagarto focal; (3) heteroespecífico del mismo sexo que el focal y (4) control, i.e., un recinto con substrato limpio. Nuestros resultados sugieren que no habría presencia de reconocimiento químico heteroespecífico, lo cual, no es consecuencia de una incapacidad para evaluar rastros químicos, puesto que ambas especies exhibieron auto reconocimiento (reconocimiento de sus rastros de olores propios) y los juveniles de L. ceii además exhibieron reconocimiento de sus conespecíficos. A pesar de que estas especies puedan beneficiarse de compartir sitios de refugio, aparentemente, el reconocimiento químico de los rastros de heterospecíficos, no modularía el sitio de refugio compartido por estas especies sintópicas. Fil: Ruiz Monachesi, Mario Ricardo. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Valdecantos, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Lobo Gaviola, Fernando Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Cruz, Felix Benjamin. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Patagonia Norte. Instituto de Investigaciones En Biodiversidad y Medioambiente. Subsede San Martín de Los Andes-inibioma | Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Instituto de Investigaciones En Biodiversidad y Medioambiente. Subsede San Martín de Los Andes-inibioma.; Argentina Fil: Labra, Antonieta. University of Oslo; Noruega

Individuals of many species utter distress calls when are attacked or trapped by a predator. These vocalizations can help them to escape but may also help conspecifics to reduce their predation risk, by inducing antipredator behaviours. Calls can encode information that modulates these antipredator responses, and the ‘nonlinearity and fear hypothesis’ proposes that complex nonlinear calls may trigger more fearful responses, because they encode higher levels of stress. We tested this hypothesis with the weeping lizard, Liolaemus chiliensis, which utters distress calls with and without nonlinear phenomena (complex and simple calls, respectively), and conspecifics respond to simple calls with antipredator behaviours. Here, we evaluated whether this species discriminates between these two types of calls, predicting higher levels of fear with complex calls. We also tested whether lizards experience less fear if calls are perceived in a safe environment, such as one full of their own scents (‘home’). Our playback experiments showed that complex calls scared the lizards more than simple calls, triggering a reduction in activity, and prolonging attempts to escape. Lizards in their own-scented environments took longer to restore their activity after hearing complex than simple calls, suggesting that this combination of stimuli was more alarming. We postulate that the predation event was unexpected at ‘home’, which together with the nonlinearity of the call made a more frightening event for the lizards. Fil: Ruiz Monachesi, Mario Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Labra Lillo, Maria Antonieta. University of Oslo. Center for Ecological and Evolutionary Synthesis; Noruega

Fires and volcanic eruptions produce ash that may negatively affect survivors of the disturbances themselves. Therefore, animals are expected to avoid areas covered by ash when possible. We tested this prediction by determining the substrate selection, ash vs. soil, in two insectivorous Liolaemus lizard species. We exposed each species to the type of ash it is most likely to encounter in its habitat: fire ash for Liolaemus lemniscatus and volcanic ash for Liolaemus pictus. We also determined the ability of these species to track insect scents in ash, as the effectiveness of scent tracking, and hence the ability to find food, may be reduced in ash. Contrary to our expectations, both species explored ash more than soil, and they were able to detect insect scents in ash. We concluded that at least shortly (e.g., days) after a disturbance involving ash production, surviving lizards may not avoid ash that may have negative impact on their health. Lizards would be able to find insects in substrates cov...

The weeping lizard, Liolaemus chiliensis, emits distress calls when trapped by a predator. Conspecific lizards respond to such calls with prolonged immobility, which may increase their probability of remaining undetected by a predator. This benefit, however, depends on the ability to react to the alert message of the call, which may be impaired by natural variation in the calls. The distress calls of L. chiliensis show geographic variation, and here we tested the response of two geographically distant populations (>700 km apart) to local (homotypic) and non-local (heterotypic) distress calls; if populations are finely tuned to their local calls, they may not be able to respond to heterotypic calls. We found that geographic variation in calls affects the lizards’ response, but this effect was population dependent; whereas southern lizards responded to calls of both populations, the northern lizards only reacted to homotypic distress calls. The factors that determine this asymmetric response to heterotypic calls are unclear and we discuss three hypotheses that have a common component in the difference in body size between the tested populations, which seems to play a key role in determining the response to distress calls in this species.

En este trabajo se describe por primera vez el despliegue de protrusion ocular en dos lagartos Liolaemidos, Liolaemus chiliensis y L. gravenhorstii. El despliegue ocurre en muy baja frecuencia y fue observado en cautiverio. Se discute la posibilidad de que las hipotesis de termorregulacion y/o de limpieza de ojos puedan explicar la ocurrencia de este despliegue en estas dos especies.

The microhabitat preferences of prey animals can modulate how they perceive predation risk, and therefore, their antipredator behaviour. We tested under standardized conditions how microhabitat preferences of two Liolaemus lizards affected their responses when confronted with two types of ambush predators (raptor vs. snake), under two levels of predation risk (low vs. high). These lizard species are sympatric, but not syntopic; L. chiliensis basks on bushes, a complex microhabitat that may provide protection against visual predators, while L. nitidus prefers open microhabitats, basking on the top of large bare rocks, highly exposed to visual predators. If microhabitat complexity modulates the antipredator response, L. chiliensis may perceive lower predation risk, exhibiting lower intensity of antipredator responses than L. nitidus. Both species reduced their activity after being exposed to both predators, but lizards differed in the assessment of predation risk; L. nitidus reduced its activity independently of the predation risk experienced, while L. chiliensis only reduced its activity in the high-risk condition. The microhabitat preferences shaped during the evolution of these species seem to modulate their perception of predation risk, which may cause interspecific differences in the associated costs of their antipredator responses.

The behavior of lizards can be highly influenced by chemical senses. The most studied pheromonal sources in lizards has been the femoral and precloacal gland secretions, although studies have been focused on male secretions, probably because these glands are usually only present in males or are poorly developed in females when they are present. Here, we aimed to study in Liolaemus chiliensis, one of the few Liolaemus species in which females have precloacal glands, if female precloacal secretions convey information. We recorded the response of both sexes to secretions from females and males, as well as to control (solvent). The lizards started to explore the secretions sooner than the control. Both sexes moved more when exposed to female secretions than to the control, and males, but not females, explored female secretions more than the other scents. These results suggest that volatile compounds of the secretions allow lizards to recognize the presence of conspecifics, and, at least for males, these trigger the exploration of non-volatile compounds of the secretions that may reveal the sex of the individual that deposited them. This is the first study that explores the response to female precloacal secretions in Liolaemus, and data indicate that the female secretions of L. chiliensis contain relevant information for social interactions. Fil: Valdecantos, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Labra, Antonieta. Universidad de Chile; Chile. University of Oslo; Noruega

In songbirds, the development of the species‐specific adult song involves a learning process that varies in extension. In species that incorporate new song elements throughout life (open‐ended learners), variation in male song composition could be the result of either age or breeding experience. Using data from 16 yr of fieldwork on pied flycatchers (Ficedula hypoleuca), we aimed to disclose the individual contribution of these two factors on the species song characteristics, as well as their relation with morphology and plumage color changes. Finally, we explored whether any of the song or physical features could predict the probability of males returning to the breeding site. We found that the song characteristics of the first‐time breeders did not differ between age classes, except for the total number of syllables per song, which was higher in the 1‐year‐old than in the 2‐year‐old males. However, we found that song variables associated with complexity (song and sample versatilities and repertoire size), increased significantly from the first to the second breeding season. Males showed delayed plumage maturation, with 1‐year‐old males being browner than the 2‐year‐old males independently of their breeding experience. Morphology, however, was not affected by age or breeding experience. The probability that males returned to the breeding site was not associated with song or physical features. Considering that some song learning occurs during the breeding period and that some males may skip the first breeding season, selective pressures may have been established for song complexity to be an honest indicator of breeding experience rather than age. This article has been accepted and published in Ethology. © 2017 Wiley

In a predator–prey interaction, the fitnesses of the predator and the prey depend on their abilities to recognize each other, a process that may involve different sensory modalities. Squamate reptiles are highly dependent on chemical senses for such recognition, and here we explored the ability of a generalist saurophagous snake, Philodryas chamissonis, to discriminate scents of two congeneric and sympatric lizard prey species, Liolaemus nitidus and L. chiliensis. A generalist saurophagous snake might just be sensitive to lizard scents in general, and if so, no discrimination between prey species is expected. However, these lizards use different substrates; L. nitidus basks on rocks, whereas L. chiliensis mainly basks on bushes and rarely on ground. The snake P. chamissonis basks on ground and rocks, and rarely on bushes. Therefore, if the rate of encounter affects the ability to recognize prey, we predict that P. chamissonis would show prey discrimination because scents of L. chiliensis may be encountered less frequently in its habitat. Results showed that the snake had a refined discrimination of lizard prey, reducing tongue flick rate and movements in response to scents from the common prey scents, L. nitidus. We also studied the ability of L. chiliensis to detect the snake and found that snake scents triggered a reduction in activity. The potential infrequent encounter between predator and prey may explain the asymmetric predator–prey recognition, as can be predicted from the “life-dinner” principle.

Mitochondrial light strand DNA replication is initiated at light strand replication origins (OLs), short stem-loop hairpins formed by the heavy strand DNA. OL-like secondary structures are also formed by heavy strand DNA templating for the five tRNAs adjacent to OLs, the WANCY tRNA cluster. We tested whether natural OL absence associates with greater capacities for formation of OL-like structures by WANCY tRNA genes. Using lepidosaurian taxa (Sphenodon, lizards and amphisbaenids), we compared WANCY tRNA capacities to form OL-like structures between 248 taxa possessing an OL with 131 taxa without OL (from different families). On average, WANCY tRNA genes form more OL-like structures in the absence of a regular OL than in its presence. Formation of OL-like structures by WANCY tRNAs follows hierarchical patterns that may reduce competition between the tRNA's translational function and its secondary OL function: the rarer the tRNA's cognate amino acid, the greater the capacity to form OL-like structures. High OL-forming capacities for neighboring tRNAs are avoided. Because OL absence usually occurs in taxa with reduced genomes, increased formation of OL-like structures by WANCY tRNAs might result from selection for greater metabolic efficiency. Further analyses suggest that OL loss is one of the latest steps in genome reduction, and promotes the increase in formation of OL-like structures by WANCY tRNA genes in Lepidosauria.

Codons expanded by a silent position (quadruplet or tetracodons) may solve the conundrum that at life's origins, the weak tricodon–anticodon interactions could not promote translation in the absence of complex ribosomes. Modern genomes have isolated tetracodons resulting from insertion mutations. Some bioinformatic analyses suggest that tetracoding stretches overlap with regular mitochondrial protein coding genes. These tetragenes are probably decoded by (antisense) tRNAs with expanded anticodons. They are GC-rich, which produce stronger basepairs than A:T interactions, suggesting expression at high temperatures. The hypothesis that tetracoding is an adaptation to high temperatures is tested here by comparing predicted mitochondrial tetracoding in Lepidosauria (lizards, amphisbaenia, and Sphenodon ), in relation to body temperature, expecting more tetracoding in species with high body temperature. The association between tRNAs with expanded anticodons and tetracoding previously described for mammals and Drosophila is confirmed for Lepidosauria. Independent evidence indicates that tetracoding increases with body temperature, supporting the hypothesis that tetracoding is an adaptation for efficient translation when conditions (temperature) make triplet codon-anticodons too unstable to allow efficient protein elongation.

In migratory birds, mistimed arrival might have negative consequences for individual fitness, causing population declines. This may happen if arrival time is not synchronized with breeding time, especially when earlier springs favour earlier reproduction. We studied spring arrival time to the breeding areas in a pied flycatcher Ficedula hypoleuca population in southern Norway during a 30-year period (1985–2014). We investigated trends in arrival both for the entire population and for different population fractions (e.g. early vs. late arrivals). We also studied sex and age class differences, along with repeatability of arrival. Finally, we explored how arrival is influenced by environmental conditions at the areas birds use throughout the year, using mixed-effects models and quantile regressions with individual-based data. Spring arrival advanced over five days, at a similar rate through the entire population. Males and adult birds arrived earlier than females and yearlings. Arrival was significantly repeatable for males and females. Birds arrived earlier in years with high temperature and rainfall at the breeding grounds, and low NDVI both on the Iberian Peninsula and in central Europe. Later fractions of the population showed a steeper response to these environmental variables. This intra-population heterogeneity in the responses to the environment probably stems from a combination between the different selection pressures individuals are subject to and their age-related experience. Our results highlight the importance of studying how migration phenology is affected by the environment not only on the breeding grounds but also on the other areas birds use throughout the year.

Species-specific recognition systems are fundamental to maintaining the cohesion of species, particularly when heterospecific matings are possible. Here, I examined whether species recognition may facilitate species isolation of Liolaemus lizards, for which up to seven closely related species with similar morphology and ecology may live in sympatry. I also tested whether coexistence with closely related species modulates species recognition. In three Liolaemus species that differ in their current need for species recognition, I investigated their abilities to discriminate chemical stimuli from conspecifics and closely related congeners. For two of these focal species, tests included sympatric and allopatric congeners. The third species, which lives without congeners, was only tested with an allopatric congener. All three species chemo-discriminated between conspecifics and congeners, responding more vigorously to scents produced by their own species. Thus, chemical stimuli may help to maintain reproductive isolation. The existence of species recognition in the allopatric species may be an ancestral trait or may have evolved as a side effect of a within-species recognition system.

The parietal, or third, eye is a photosensory organ situated in the middle of the skull of many lizards. Despite many hypotheses, its exact ecological functions are still unclear. Studies have compared the presence and absence of a functioning parietal eye, although there are no quantitative studies of parietal-eye traits in relation to ecology, physiology or behaviour. In the present study, we report the first comparative study of relative parietal-eye size in relation to climatic and thermophysiological variables. We studied thirty species of Liolaemus, a genus of South-American lizards inhabiting a range of climatic conditions, but found little evidence for adaptation to thermal environment, in that parietal-eye size did not vary meaningfully with latitude, altitude or any measures of environmental temperature. Neither did it relate to thermophysiology; there was a weak relation to thermal tolerance, although this was partially confounded with body size, which explained 23% of the among-species variance after controlling for within-species variation. The negative results obtained could not be explained by phylogenetic constraints because we found no evidence of phylogenetic inertia. We also observed high intraspecific variation indicating that parietal-eye size may not be under strong selection for accuracy. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 870–883.

Microevolutionary studies often find that complex quantitative characters are highly evolvable and adapted to the local environment, while macroevolutionary studies often show evidence of strong phylogenetic effects and stasis. In this contribution, we show how phylogenetic comparative methods can be used to test hypotheses that may help resolve this paradox. As a test case, we studied the interplay between adaptation and phylogenetic inertia on the thermobiology of 32 species of Liolaemus (Squamata: Liolaemidae), a genus of South American lizards living under diverse climatic conditions. Despite a strong phylogenetic effect in the preferred (selected) body temperature, we found clear evidence that this variable is adapted to local temperature and climate. After controlling for adaptation to the thermal environment, little influence of phylogeny was left. This indicates that the phylogenetic effect was not caused by a lag or slowness in adaptation but primarily by the distribution of the thermal environments on the phylogeny. This can be due to thermal niche tracking. In contrast, we found little or no evidence for adaptation to the thermal environment in either cooling or heating rates, critical thermal minimum, or body size.

Several studies have evaluated the relative contribution of various host-plant attributes to the species richness of the associated insect herbivores, with and without the inclusion of the phylogeny of the host species for Northern hemisphere trees. In general these studies reached the same conclusion: tree availability (range and abundance) was a good predictor of insect species richness, although chemical attributes of the trees were not tested. The present study evaluates the relative contribution of ecological attributes of host-plant species within the Southern hemisphere genus Nothofagus, to the species richness of their associated insect fauna in South America and New Zealand. The variables included were: area of distribution (a), including longitudinal (rln) and latitudinal ranges (rlt), architectural complexity (c) and phytochemical attributes of the species, including chemical diversity (d) and chemical uniqueness (u). The analysis by independent contrasts revealed that the latitudinal range is an important factor, which explained the insect richness associated with Nothofagus for all guilds and taxonomic orders, except for the sap feeders. Compared to the non-phylogenetic analyses, including host-plant phylogeny led to the inclusion of additional variables in the regression equations. Phytochemical uniqueness of the host plants was an important factor to explain insect species richness. For example, Nothofagus alessandrii, the species with the most unique chemistry, had very few and mostly specialised herbivores, whereas Nothofagus dombeyi, with the least unique chemistry, had the highest number of related insect species. We conclude that, in addition to geographic range and phylogenetic relatedness, studies of insect herbivore diversity must also examine plant chemical composition.

Social–chemical recognition is exhibited by all the Liolaemus lizards tested to date, except Liolaemus fitzgeraldi, which during post-hibernation did not discriminate chemosignals of same-sex individuals from a control. To clarify if L. fitzgeraldi is unique among the studied Liolaemus in lacking social–chemical recognition or if this was previously undetected, we recorded behavior during pre- and post-hibernation when confronted with chemosignals of conspecifics and from themselves. L fitzgeraldi showed self-recognition and seasonal changes in two exploratory behaviors. Potentially, conspecific recognition in L fitzgeraldi was undetected due to seasonality, but this species may rely comparatively less on chemical communication than congeners.

Ecological and phylogenetic factors determine which sensory modalities organisms use in their day-to-day activities. Among lizards, empirical studies indicate a tight association between foraging strategies and the ability to detect chemical cues from prey. Consequently, ambush insectivores do not detect food chemicals and these differences have a phylogenetic basis, as ambush lizards mainly belong to the Iguania clade. These data contrast, however, with the widespread uses of chemoreception in the Iguania genus Liolaemus, which are mostly insectivorous ambush predators. Moreover, observations from different Liolaemus species suggest a capability to find prey through chemoreception. In order to clarify the abilities of Liolaemus to detect chemical cues from prey, the chemoreceptive behavior of the insectivorous ambush predator, L. lemniscatus, was studied. Lizards were given the choice between areas with and without chemical cues from a food item (mealworms). Results show that test animals stayed for longer, moved more, and did more chemical exploration (tongue flicks) in the area where chemical cues from mealworms were present. Furthermore, in this area, more individuals displayed behaviors that suggest maintenance and defense of the prey patch. Thus, L. lemniscatus is the first insectivorous Iguania reported to be able to detect chemical cues from prey. Although I propose a mechanism for acquiring chemical detection of prey cues in Liolaemus, I also remark that it is necessary to reanalyze both the abilities to detect and use chemical foraging cues in Iguania at large, and the methodologies traditionally used to study these issues.

Males from different iguanian lizard species engage in frequent visual signaling during agonistic interactions, mainly by displaying head bobs. We conducted a detailed study of the structure of head bob displays mediating male agonistic interactions in Liolaemus lemniscatus lizards. We staged pair-wise encounters where one male, the intruder, was placed in the terrarium of a conspecific male, the resident. During these interactions, males exhibited only one type of head bob display made up of three distinct units: a low amplitude bob (unit 1), a brief pause (unit 2), and two consecutive high-amplitude bobs (unit 3). Head bob displays occurred singly or as a part of a bout, with a mean number of head bob displays per bout of two. Total head bob display duration was stereotyped. The highest inter-individual variation (duration and amplitude) was recorded for unit 3, suggesting that this unit may provide information about the individual identity of the sender. Winners of interactions performed more head bob displays than losers, and these were composed of units of longer duration and higher amplitude than head bob displays exhibited by losers. Although preliminary, our results suggest that, in L. lemniscatus, head bob displays may facilitate opponent assessment by conveying information about individual fighting ability, motivation, or dominance status.

Philodryas chamissonis is a rear-fanged snake endemic to Chile. Its bite produces mild to moderate symptoms with proteolytic and anti-coagulant effects. Presently, the composition of the venom, as well as, the biochemical and structural characteristics of its toxins, remains unknown. In this study, we cloned and reported the first full-length sequences of five toxin-encoding genes from the venom gland of this species: Type III snake venom metalloprotease (SVMP), snake venom serine protease (SVSP), Cysteine-rich secretory protein (CRISP), α and β subunits of C-type lectin-like protein (CLP) and C-type natriuretic peptide (NP). These genes are highly expressed in the venom gland and their sequences exhibited a putative signal peptide, suggesting that these are components of the venom. These putative toxins had different evolutionary relationships with those reported for some front-fanged snakes, being SVMP, SVSP and CRISP of P. chamissonis closely related to the toxins present in Elapidae species, while NP was more related to those of Viperidae species. In addition, analyses suggest that the α and β subunits of CLP of P. chamissonis might have a α-subunit scaffold in common with Viperidae species, whose highly variable C-terminal region might have allowed the diversification in α and β subunits. Our results provide the first molecular description of the toxins possibly implicated in the envenomation of prey and humans by the bite of P. chamissonis.

When an individual faces the risk of a conflict, its ability to make ‘correct’ decisions is crucial to its fitness. Research on decision making has focused mainly on visual and acoustic signals, while chemical signals have received much less attention, despite their relevance for many species. Chemosignals can be detected in the absence of the signaller and, in the context of fighting risk, this property confers the advantage that the receiver can avoid agonistic interactions or, if they are unavoidable, that it can prepare itself for the conflict. I studied the behaviour of males of the lizard Liolaemus monticola in the laboratory when they were confronted with chemosignals of a potential opponent. During this ‘pre-confrontation’ stage, I tested the following predictions: (1) lizards can derive precise information from chemosignals of conspecifics, and use this to respond with precision to the perceived risk and (2) the best predictor of the receiver behaviour, and therefore the best predictor of the risk involved in the fight, is the relative fighting ability of opponents. As a measure of fighting ability, I used body size. ‘Intruders’ were placed in the terrarium of unfamiliar ‘residents’ during the absence of the latter, and their behaviours were recorded. Simple regressions were performed between the different behavioural variables and with the body sizes of intruder and resident, and with the relative difference in body sizes of opponents. The latter was the best predictor of intruder behaviour: it was negatively correlated with behaviours associated with activity (i.e. motion time), chemoexploration (i.e. number of tongue flicks) and behaviours associated with social interactions (i.e. head bobs). These results suggest that males can process information from chemosignals and decisions made during the ‘pre-confrontation’ stage are based on the assessment of the relative fighting abilities (i.e. relative body size) of opponents.

Liolaemus lizards were explored to ascertain whether they would make an amenable model to study single-cell electrophysiology of neurons in the vomeronasal organ (VNO). Despite a rich array of chemosensory-related behaviors chronicled for this genus, no anatomical or functional data exist for the VNO, the organ mediating these types of behaviors. Two Liolaemus species ( L. bellii and L. nigroviridis) were collected in Central Chile in the Farellones Mountains and transported to the United States. Lizards were subjected to hypothermia and then a lethal injection of sodium pentabarbitol prior to all experiments described in the following text. Retrograde dye perfusion combined with histological techniques demonstrated a compartmentalization of the proportionally large VNO from the main olfactory epithelium (MOE) in cryosections of L. bellii. SDS-PAGE analysis of the VNO of both species demonstrated the expression of three G protein subunits, namely, Gαo, Gαi2, and Gβ, and the absence of Gαolf, Gα11, and Gq, the latter of which are traditionally found in the MOE. Vomeronasal (VN) neurons were enzymatically isolated for whole cell voltage-clamp electrophysiology of single neurons. Both species demonstrated a tetrodotoxin (TTX)-sensitive, rapidly inactivating sodium current and a tetraethylammonium (TEA)-sensitive potassium current that had a transient and sustained component. VN neurons were classified into two types dependent on the ratio of sodium over sustained potassium current. VN neurons exhibited outward and inward chemosignal-evoked currents when stimulated with pheromone-containing secretions taken from the feces, skin, and precloacal pores. Fifty-nine percent of the neurons were responsive to at least one compound when presented with a battery of five different secretions. The breadth of responsiveness (H metric) demonstrated a heterogeneous population of tuning with a mean of 0.29.