Poblaciones urbanas de la lagartija ibérica: Uso como bioindicador de los efectos del ambiente ur... more Poblaciones urbanas de la lagartija ibérica: Uso como bioindicador de los efectos del ambiente urbano COLECCIÓN NATURALEZA Y MEDIO AMBIENTE 1-26 PUBLICACIONES DE LA 1ª A LA 11ª CONVOCATORIA DE BECAS DE MEDIO AMBIENTE 12º CONVOCATORIA 27 Impacto sobre la avifauna de la implantación del plan de gestión de los residuos sólidos urbanos en Segovia. 28 Programa educativo de recuperación de actividades tradicionales en la tierra de pinares segoviana. 29 Contaminación lumínica y derroche energético en la ciudad de Segovia. 30 Andar y ver el nordeste de Segovia. 31 Guía de plantas medicinales en la provincia de Segovia. 13º CONVOCATORIA 32 Itinerario geológico en Armuña. Recorrido didáctico a pie en la provincia de Segovia. 33 La biomasa y los biocarburantes en la provincia de Segovia.
The mechanisms that confer honesty to multiple sexual signals of vertebrates remain less known. W... more The mechanisms that confer honesty to multiple sexual signals of vertebrates remain less known. We suggest that vitamin E in the scent (femoral secretions) and carotenoids in coloration of Lacerta lepida lizards might advertise quality because they are relevant in metabolism as major antioxidants and have a dietary origin. Results showed that there may be similar trade-offs between immunity and both chemical and visual signaling, as males with more vitamin E in secretions and those with more greenish, darker, and saturated carotenoid-dependent colorations had a higher immune response. This suggests that only high-quality males can divert from metabolism and allocate enough vitamin E to secretions and enough carotenoids to coloration. Therefore, information provided by visual and chemical signals is congruent. The use of multiple sensory channels may allow signaling a male quality under different circumstances or reinforce the reliability of the signal when both signals are perceived simultaneously. However, we also found that characteristics of carotenoid-dependent coloration mirror the amounts of vitamin E in secretions. This might support that carotenoids, which are not true antioxidants in the organism, would just reflect and "inform" on the actual contents of metabolic antioxidant vitamin E, which is part of the true system that prevent oxidation. We suggest that the metabolic roles of vitamins might be the actual basis of honesty of many sexual displays, and that carotenoid-based signals might be just the visible part of the whole system.
Many animals use chemical signals in sexual selection, but it is not clear how these sexual trait... more Many animals use chemical signals in sexual selection, but it is not clear how these sexual traits might have evolved to signal honestly male condition. It is possible that there is a trade-off between maintaining the immune system and the elaboration of ornaments. We experimentally challenged the immune system of male Iberian wall lizards, Podarcis hispanica, with a bacterial antigen (lipopolysaccharide), without pathogenic effects, to explore whether the immune activation affected chemical ornaments. Immune activation resulted in decreased proportions of a major chemical in femoral secretions (cholesta-5,7-dien-3-ol = provitamin D 3) known to be selected in scent of males by females and which active form (vitamin D) has a variety of important effects on immune system function. This result suggests the existence of a potential trade-off between physiological regulation of the immune system and the allocation of essential nutrients (vitamins) to sexual chemical ornaments in male lizards.
Pheromones of vertebrates are often a mixture of several chemicals with different properties and ... more Pheromones of vertebrates are often a mixture of several chemicals with different properties and messages, and their production seems condition dependent. Thus, pheromones are a good, but little studied, example of multiple sexual signals. Femoral gland secretions of male rock lizards Iberolacerta cyreni contain steroids that may act as pheromones, but there are also many other lipids, such as oleic acid, whose allocation to secretions may be costly because it has to be diverted from body fat reserves. This suggests that oleic acid could also have some function in secretions. Chemical analyses showed that proportions of oleic acid in femoral secretions of males were positively related to body condition of males, suggesting that the oleic acid secreted may reflect the amount of body fat reserves of a male. Tongue-flick bioassays showed that females were able to detect by chemosensory cues alone differences in proportions of oleic acid in secretions of males. Scents of males with more oleic acid elicited stronger chemosensory responses by females. Further tests with chemical standards confirmed that females distinguished oleic acid, and changes in its concentration, from other chemicals that are naturally found in secretions of males. Moreover, choice trials of scent-marked substrates showed that females were more attracted to areas that were experimentally manipulated to increase the proportion of oleic acid in natural scent marks of males. We suggest that oleic acid in femoral secretions might be a reliable advertisement of a male's body condition, which females could use to select highquality mates in conjunction with information provided by other chemicals. Alternatively, scent marks with more oleic acid might be simply more attractive to females if chemosensory responses of females to scent of males were originated by a preexisting sensory bias for food chemicals such as the oleic acid. Nevertheless, this sensory trap might have evolved into an honest signal because the elaboration of the signal seems differentially costly for males with different body conditions.
We studied the relationships between thermoregulatory basking postures and heating rates in the I... more We studied the relationships between thermoregulatory basking postures and heating rates in the Iberian rock lizard (Lacerta monticola). Heating rates were high when body size was small, the substrate temperature was high, and the angle of incidence of the sun's rays was high (i.e., the rays were perpendicular to the lizard's body). However, heating rates were not related to the compass orientation of lizard's body axis to the sun (perpendicular versus in line with the sun). In the field, the slopes of the body axis of basking individuals were higher during the early morning. However, neither the cardinal orientation of a lizard's body axis to the sun nor the frequency of flattening varied during the morning. Postural adjustments to select an adequate angle of incidence of the sun's rays on the dorsal part of the body suggest that this behaviour might enhance absorption of solar radiation.
In spite of the importance of chemoreception in sexual selection of lizards, only a few studies h... more 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.
In species with reduced locomotory abilities, camouflage seems to be f a r more important than ot... more In species with reduced locomotory abilities, camouflage seems to be f a r more important than other behavioural tactics (e.g. running) to elude predatory attacks. In this study, we examined the effects of camouflage on escape decisions in the common chameleon Chamaeleo chamaeleon. The effectiveness of camouflage was assessed by the ability of humans to detect different sized chameleons placed on different backgrounds (vegetation of high and low density, defined here as open and dense bushes), both in the field and in photographs. Escape behaviour was analysed by simulating a predator attack (in our case, approach by a human). As expected, the probability of detection by a potential predator was size-and background dependent. In the field, detection time (but not distance) was significantly higher for chameleons of a given size perched on dense (Myoporum) than open (Retama) bushes. When using photographs, the probability of detection was higher for large (adult) chameleons perched on open (Retama or Nerium) bushes and lower for hatchlings perched on dense (Myoporum or Cupressus) bushes. Conspicuousness greatly influenced the escape tactics of individuals. Chameleons perched on more protected Myoporum allowed closest approach distances than those perched on less protected Retama. In general, antipredatory responses (defined here as 'first movement', 'fleeing', 'mouth opening' or 'free falling') occurred significantly earlier in the trial sequence in chameleons perched on clear Retama than those perched in Myoporum. Two antipredatory responses were size-dependent: juveniles and adults exhibited 'mouth opening' more frequently than hatchlings whereas 'free falling' was more frequently recorded for hatchlings, Our results suggest that size and vegetation greatly influence the risk of detection by predators and this variation influences an individual's decision about when and how to escape.
... Thus, we also compared the surface-to-volume ratios of the two species, basing on biometric m... more ... Thus, we also compared the surface-to-volume ratios of the two species, basing on biometric measures, and their effects on thermal exchange rates. Materials and methods Study animals ... 1973; Slip and Shine 1988; Spotila et al. 1991). ...
The red-eared slider (Trachemys scripta elegans) is a worldwide highly invasive species, currentl... more The red-eared slider (Trachemys scripta elegans) is a worldwide highly invasive species, currently introduced in most freshwater habitats as a consequence of massive pet trade. In the Iberian Peninsula, this species is competing with and displacing the endangered native Spanish terrapin (Mauremys leprosa). Sliders are considered environmentally-aggressive turtles, capable of threatening or biting other individuals during competitive activities such as
In spite of the importance of feces in scent marking and intraspecific chemical communication of ... more In spite of the importance of feces in scent marking and intraspecific chemical communication of many mammals, only a few studies have examined the chemical constituents of feces that could have a signaling function. We described here the chemicals found in feces recently deposited in the wild by adult and pup Iberian wolves (Canis lupus signatus). By means of analyses using gas chromatography-mass spectrometry (GC-MS), we identified 77 compounds in feces of adult wolves, mainly heterocyclic aromatic organic compounds, such as indole or phenol, but also steroids, such as cholesterol, carboxylic acids and their esters between n-C 3 and n-C 18 , aldehydes, alcohols and significant quantities of squalene and atocopherol, which would increase the chemical stability of feces on humid substrates. Some of the odoriferous compounds are very likely originated in the anal-sac secretions, and later incorporated onto feces during defecation. However, the abundance of the main odoriferous compounds in feces could be explained by the result of the bacterial action on food components. Feces of pups only had 26 compounds, most of these were also found in adults' feces, but four compounds were only found in pups' feces, and there were also age-related differences respect to the proportions of shared chemicals. These differences could be partly due to the absence of anal-sac glands in pups, which would not need to scent mark substrates.
Prey should balance cost and benefits when deciding optimal refuge use. In ectotherms, such as li... more Prey should balance cost and benefits when deciding optimal refuge use. In ectotherms, such as lizards, body temperature can decrease in cold refuges, which has negative effects on physiological and locomotor performance. Thus, refuge use of ectotherms should be influenced by the thermal environment as well as by the body size-dependent thermal inertia of each individual. We simulated predator attacks to Schreiber's Green lizards (Lacerta schreiberi) and analyzed their refuge use. Results indicated that temperatures outside and inside a refuge had opposite effects on refuge use decisions. Thus, when initial external temperatures were higher and lizards had higher thermal inertia, lizards could spend longer times inside refuges before reaching a 'critical' low body temperature. However, when refuge temperature was low lizards did not decrease refuge use. If low refuge temperatures increased risk upon emerging because lizards had lower escape performance, lizards would need to compensate by remaining in a refuge for longer to scan the surroundings before emerging to ensure that the risk of a new attack decreased. Therefore, when deciding refuge use, L. schreiberi lizards seem to consider physiological costs of being at low temperatures and also the risk of emerging with low escape performance.
Animals should adopt strategies to minimize the costs of intraspecific aggressive interactions. F... more Animals should adopt strategies to minimize the costs of intraspecific aggressive interactions. For example, individuals should be able to identify resource holders in advance and avoid fighting with them because residents are generally more likely than intruders escalate aggression. It has been suggested that scent marks function mainly to allow competitor assessment by conveying the costs of entering a scent-marked area. Individuals may identify territory owners by comparing the scent of substrate marks with the scent of any conspecific they encounter nearby, assessing whether these two scents match or not, a mechanism known as scent matching. Here, we examined the response of male Iberolacerta cyreni lizards to areas scent-marked by other males and the potential role of scent matching in agonistic interactions. We designed a laboratory experiment where we allowed a male to explore the scent-marked substrate of another male, and then we immediately staged agonistic encounters in a nearby clean neutral area with either the male that had produced the scent marks (matching treatment) or with a different nonmatching individual male. The higher chemosensory exploratory rates of substrate scent marks in comparison to clean substrates suggested that males detected and spent more time exploring scent marks to obtain information on the donor male. Moreover, this information was later used to decide the fighting strategy. Intruding males delayed time until the first agonistic interaction, reduced the intensity of fights and the number of aggressive interactions, and won less interactions with males which scent matched that of scent marks (because they would be considered as the territory owners) than with other non-matching individuals. Our results show that male I. cyreni lizards use scent matching as a mechanism to assess the ownership status of other males, which could contribute to modulate intrasexual aggression, reducing costs of agonistic interactions.
Sexual signals can be evolutionarily stable if they are honest and condition-dependent or costly ... more Sexual signals can be evolutionarily stable if they are honest and condition-dependent or costly to the signaler. One possible cost is the existence of a trade-off between maintaining physiological health and elaboration of ornaments, such that only healthier individuals may afford to produce more elaborate sexual displays. We analyzed the relationship between head coloration and health state of Trachemys scripta elegans turtles. Results showed that turtles with a higher immune response and with a higher body condition had postorbital red patches with brighter coloration with higher values of long-wavelength reflectance (i.e., more reddish). Similarly, turtles with a higher immune response and with a lower heterophil/lymphocyte (H/L) ratio had chin yellow stripes with darker coloration with higher values of medium wavelengths (i.e., more yellowish). These relationships suggest that the health state of T. scripta elegans turtles is reflected by the colorful skin patches and stripes of the head. Characteristics of coloration did not differ between sexes, suggesting that this visual signal may be used by both sexes in intrasexual and intersexual communication. Because many other turtle species have similar colorful patches, it is likely that coloration may have a still unexplored significant role in sexual selection in many turtles.
Morphological adaptations for burrowing, such as an elongated body, and a small head may constrai... more Morphological adaptations for burrowing, such as an elongated body, and a small head may constrain feeding behaviour in fossorial reptiles. We experimentally examined the effect of prey type on prey capture and handling behaviour of the amphisbaenian Blanus cinereus. This amphisbaenian showed four different handling modes according to the characteristics of each prey type. When prey diameter was narrower than gape-size, prey were consumed without prey processing; when prey diameter was wider than gape-size, B. cinereus shifted handling mode to prey processing. Amphisbaenians scraped or tore off bite-sized pieces of large prey and showed longer handling times for some prey types than most epigean saurians. Flexibility in feeding behaviour may allow amphisbaenians to exploit variable underground trophic resources, overcoming constraints of morphological adaptation to fossoriality.
The ecology and behaviour of Amphisbaenians is poorly known due to their fossorial habits. Howeve... more The ecology and behaviour of Amphisbaenians is poorly known due to their fossorial habits. However, amphisbaenians are often found under rocks where they thermoregulate, and probably engage in social interactions. We describe aggregations under rocks in a North African population of the little studied amphisbaenian Trogonophis wiegmanni. These observations could be used to make initial inferences about the social behaviour of this amphisbaenian. Results showed that amphisbaenians were sometimes found in pairs under the same rock. However, these aggregations were not random. Adult males were only found together with adult females, but we did not find pairs of adult males or adult females. This might suggest that there is intra-sexual intolerance, and that adult individuals of the same sex do not occupy the same rock space. Pairs of adults were more frequently found in spring than in autumn, coinciding with the mating season. Also, juvenile individuals were often found together with an adult, but juveniles tended to be more often with an adult female than with an adult male. This might indicate that juveniles are allowed to remain with their parents until they are older, which might enhance offspring fitness by providing access to high-quality habitats.
Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards... more Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards. Here, we hypothesised that juvenile Iberian rock lizards (Lacerta (=Iberolacerta) monticola) use substrate-borne conspecific faecal chemicals to assess the social environment and base their spatial decisions. To test this hypothesis, we prepared chemical stimuli by dissolving faeces in an organic solvent (dichloromethane, DCM) and conducted chemosensory trials where we quantified latency to the first tongue flick (TF) and TF rates when young captive-borne juveniles were placed in an arena compartment whose substrate was labelled by (1) a control (DCM), (2) their own faecal chemicals, (3) faecal chemicals of another juvenile, (4) faecal chemicals of an adult female or (5) faecal chemicals of an adult male. Following TF observations, we removed a partition that separated the labelled compartment from a chemically unlabelled one, and recorded for 5 min when juveniles first crossed to the unlabelled compartment and total time spent in the labelled compartment. Each juvenile was tested with all stimuli in a randomised order. In addition, juveniles belonged to different families and were unrelated to and unfamiliar with faeces donors. Taken together, TF and spatial responses toward stimuli indicate that juveniles discriminated between faecal chemicals of conspecific juveniles, adult females and males, and that they avoided remaining in substrates labelled by adult male faecal chemicals. We suggest that juveniles assess the social environment based on conspecific faecal chemicals thus avoiding aggression and cannibalistic risks undertaken from encounters with adult males.
Poblaciones urbanas de la lagartija ibérica: Uso como bioindicador de los efectos del ambiente ur... more Poblaciones urbanas de la lagartija ibérica: Uso como bioindicador de los efectos del ambiente urbano COLECCIÓN NATURALEZA Y MEDIO AMBIENTE 1-26 PUBLICACIONES DE LA 1ª A LA 11ª CONVOCATORIA DE BECAS DE MEDIO AMBIENTE 12º CONVOCATORIA 27 Impacto sobre la avifauna de la implantación del plan de gestión de los residuos sólidos urbanos en Segovia. 28 Programa educativo de recuperación de actividades tradicionales en la tierra de pinares segoviana. 29 Contaminación lumínica y derroche energético en la ciudad de Segovia. 30 Andar y ver el nordeste de Segovia. 31 Guía de plantas medicinales en la provincia de Segovia. 13º CONVOCATORIA 32 Itinerario geológico en Armuña. Recorrido didáctico a pie en la provincia de Segovia. 33 La biomasa y los biocarburantes en la provincia de Segovia.
The mechanisms that confer honesty to multiple sexual signals of vertebrates remain less known. W... more The mechanisms that confer honesty to multiple sexual signals of vertebrates remain less known. We suggest that vitamin E in the scent (femoral secretions) and carotenoids in coloration of Lacerta lepida lizards might advertise quality because they are relevant in metabolism as major antioxidants and have a dietary origin. Results showed that there may be similar trade-offs between immunity and both chemical and visual signaling, as males with more vitamin E in secretions and those with more greenish, darker, and saturated carotenoid-dependent colorations had a higher immune response. This suggests that only high-quality males can divert from metabolism and allocate enough vitamin E to secretions and enough carotenoids to coloration. Therefore, information provided by visual and chemical signals is congruent. The use of multiple sensory channels may allow signaling a male quality under different circumstances or reinforce the reliability of the signal when both signals are perceived simultaneously. However, we also found that characteristics of carotenoid-dependent coloration mirror the amounts of vitamin E in secretions. This might support that carotenoids, which are not true antioxidants in the organism, would just reflect and "inform" on the actual contents of metabolic antioxidant vitamin E, which is part of the true system that prevent oxidation. We suggest that the metabolic roles of vitamins might be the actual basis of honesty of many sexual displays, and that carotenoid-based signals might be just the visible part of the whole system.
Many animals use chemical signals in sexual selection, but it is not clear how these sexual trait... more Many animals use chemical signals in sexual selection, but it is not clear how these sexual traits might have evolved to signal honestly male condition. It is possible that there is a trade-off between maintaining the immune system and the elaboration of ornaments. We experimentally challenged the immune system of male Iberian wall lizards, Podarcis hispanica, with a bacterial antigen (lipopolysaccharide), without pathogenic effects, to explore whether the immune activation affected chemical ornaments. Immune activation resulted in decreased proportions of a major chemical in femoral secretions (cholesta-5,7-dien-3-ol = provitamin D 3) known to be selected in scent of males by females and which active form (vitamin D) has a variety of important effects on immune system function. This result suggests the existence of a potential trade-off between physiological regulation of the immune system and the allocation of essential nutrients (vitamins) to sexual chemical ornaments in male lizards.
Pheromones of vertebrates are often a mixture of several chemicals with different properties and ... more Pheromones of vertebrates are often a mixture of several chemicals with different properties and messages, and their production seems condition dependent. Thus, pheromones are a good, but little studied, example of multiple sexual signals. Femoral gland secretions of male rock lizards Iberolacerta cyreni contain steroids that may act as pheromones, but there are also many other lipids, such as oleic acid, whose allocation to secretions may be costly because it has to be diverted from body fat reserves. This suggests that oleic acid could also have some function in secretions. Chemical analyses showed that proportions of oleic acid in femoral secretions of males were positively related to body condition of males, suggesting that the oleic acid secreted may reflect the amount of body fat reserves of a male. Tongue-flick bioassays showed that females were able to detect by chemosensory cues alone differences in proportions of oleic acid in secretions of males. Scents of males with more oleic acid elicited stronger chemosensory responses by females. Further tests with chemical standards confirmed that females distinguished oleic acid, and changes in its concentration, from other chemicals that are naturally found in secretions of males. Moreover, choice trials of scent-marked substrates showed that females were more attracted to areas that were experimentally manipulated to increase the proportion of oleic acid in natural scent marks of males. We suggest that oleic acid in femoral secretions might be a reliable advertisement of a male's body condition, which females could use to select highquality mates in conjunction with information provided by other chemicals. Alternatively, scent marks with more oleic acid might be simply more attractive to females if chemosensory responses of females to scent of males were originated by a preexisting sensory bias for food chemicals such as the oleic acid. Nevertheless, this sensory trap might have evolved into an honest signal because the elaboration of the signal seems differentially costly for males with different body conditions.
We studied the relationships between thermoregulatory basking postures and heating rates in the I... more We studied the relationships between thermoregulatory basking postures and heating rates in the Iberian rock lizard (Lacerta monticola). Heating rates were high when body size was small, the substrate temperature was high, and the angle of incidence of the sun's rays was high (i.e., the rays were perpendicular to the lizard's body). However, heating rates were not related to the compass orientation of lizard's body axis to the sun (perpendicular versus in line with the sun). In the field, the slopes of the body axis of basking individuals were higher during the early morning. However, neither the cardinal orientation of a lizard's body axis to the sun nor the frequency of flattening varied during the morning. Postural adjustments to select an adequate angle of incidence of the sun's rays on the dorsal part of the body suggest that this behaviour might enhance absorption of solar radiation.
In spite of the importance of chemoreception in sexual selection of lizards, only a few studies h... more 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.
In species with reduced locomotory abilities, camouflage seems to be f a r more important than ot... more In species with reduced locomotory abilities, camouflage seems to be f a r more important than other behavioural tactics (e.g. running) to elude predatory attacks. In this study, we examined the effects of camouflage on escape decisions in the common chameleon Chamaeleo chamaeleon. The effectiveness of camouflage was assessed by the ability of humans to detect different sized chameleons placed on different backgrounds (vegetation of high and low density, defined here as open and dense bushes), both in the field and in photographs. Escape behaviour was analysed by simulating a predator attack (in our case, approach by a human). As expected, the probability of detection by a potential predator was size-and background dependent. In the field, detection time (but not distance) was significantly higher for chameleons of a given size perched on dense (Myoporum) than open (Retama) bushes. When using photographs, the probability of detection was higher for large (adult) chameleons perched on open (Retama or Nerium) bushes and lower for hatchlings perched on dense (Myoporum or Cupressus) bushes. Conspicuousness greatly influenced the escape tactics of individuals. Chameleons perched on more protected Myoporum allowed closest approach distances than those perched on less protected Retama. In general, antipredatory responses (defined here as 'first movement', 'fleeing', 'mouth opening' or 'free falling') occurred significantly earlier in the trial sequence in chameleons perched on clear Retama than those perched in Myoporum. Two antipredatory responses were size-dependent: juveniles and adults exhibited 'mouth opening' more frequently than hatchlings whereas 'free falling' was more frequently recorded for hatchlings, Our results suggest that size and vegetation greatly influence the risk of detection by predators and this variation influences an individual's decision about when and how to escape.
... Thus, we also compared the surface-to-volume ratios of the two species, basing on biometric m... more ... Thus, we also compared the surface-to-volume ratios of the two species, basing on biometric measures, and their effects on thermal exchange rates. Materials and methods Study animals ... 1973; Slip and Shine 1988; Spotila et al. 1991). ...
The red-eared slider (Trachemys scripta elegans) is a worldwide highly invasive species, currentl... more The red-eared slider (Trachemys scripta elegans) is a worldwide highly invasive species, currently introduced in most freshwater habitats as a consequence of massive pet trade. In the Iberian Peninsula, this species is competing with and displacing the endangered native Spanish terrapin (Mauremys leprosa). Sliders are considered environmentally-aggressive turtles, capable of threatening or biting other individuals during competitive activities such as
In spite of the importance of feces in scent marking and intraspecific chemical communication of ... more In spite of the importance of feces in scent marking and intraspecific chemical communication of many mammals, only a few studies have examined the chemical constituents of feces that could have a signaling function. We described here the chemicals found in feces recently deposited in the wild by adult and pup Iberian wolves (Canis lupus signatus). By means of analyses using gas chromatography-mass spectrometry (GC-MS), we identified 77 compounds in feces of adult wolves, mainly heterocyclic aromatic organic compounds, such as indole or phenol, but also steroids, such as cholesterol, carboxylic acids and their esters between n-C 3 and n-C 18 , aldehydes, alcohols and significant quantities of squalene and atocopherol, which would increase the chemical stability of feces on humid substrates. Some of the odoriferous compounds are very likely originated in the anal-sac secretions, and later incorporated onto feces during defecation. However, the abundance of the main odoriferous compounds in feces could be explained by the result of the bacterial action on food components. Feces of pups only had 26 compounds, most of these were also found in adults' feces, but four compounds were only found in pups' feces, and there were also age-related differences respect to the proportions of shared chemicals. These differences could be partly due to the absence of anal-sac glands in pups, which would not need to scent mark substrates.
Prey should balance cost and benefits when deciding optimal refuge use. In ectotherms, such as li... more Prey should balance cost and benefits when deciding optimal refuge use. In ectotherms, such as lizards, body temperature can decrease in cold refuges, which has negative effects on physiological and locomotor performance. Thus, refuge use of ectotherms should be influenced by the thermal environment as well as by the body size-dependent thermal inertia of each individual. We simulated predator attacks to Schreiber's Green lizards (Lacerta schreiberi) and analyzed their refuge use. Results indicated that temperatures outside and inside a refuge had opposite effects on refuge use decisions. Thus, when initial external temperatures were higher and lizards had higher thermal inertia, lizards could spend longer times inside refuges before reaching a 'critical' low body temperature. However, when refuge temperature was low lizards did not decrease refuge use. If low refuge temperatures increased risk upon emerging because lizards had lower escape performance, lizards would need to compensate by remaining in a refuge for longer to scan the surroundings before emerging to ensure that the risk of a new attack decreased. Therefore, when deciding refuge use, L. schreiberi lizards seem to consider physiological costs of being at low temperatures and also the risk of emerging with low escape performance.
Animals should adopt strategies to minimize the costs of intraspecific aggressive interactions. F... more Animals should adopt strategies to minimize the costs of intraspecific aggressive interactions. For example, individuals should be able to identify resource holders in advance and avoid fighting with them because residents are generally more likely than intruders escalate aggression. It has been suggested that scent marks function mainly to allow competitor assessment by conveying the costs of entering a scent-marked area. Individuals may identify territory owners by comparing the scent of substrate marks with the scent of any conspecific they encounter nearby, assessing whether these two scents match or not, a mechanism known as scent matching. Here, we examined the response of male Iberolacerta cyreni lizards to areas scent-marked by other males and the potential role of scent matching in agonistic interactions. We designed a laboratory experiment where we allowed a male to explore the scent-marked substrate of another male, and then we immediately staged agonistic encounters in a nearby clean neutral area with either the male that had produced the scent marks (matching treatment) or with a different nonmatching individual male. The higher chemosensory exploratory rates of substrate scent marks in comparison to clean substrates suggested that males detected and spent more time exploring scent marks to obtain information on the donor male. Moreover, this information was later used to decide the fighting strategy. Intruding males delayed time until the first agonistic interaction, reduced the intensity of fights and the number of aggressive interactions, and won less interactions with males which scent matched that of scent marks (because they would be considered as the territory owners) than with other non-matching individuals. Our results show that male I. cyreni lizards use scent matching as a mechanism to assess the ownership status of other males, which could contribute to modulate intrasexual aggression, reducing costs of agonistic interactions.
Sexual signals can be evolutionarily stable if they are honest and condition-dependent or costly ... more Sexual signals can be evolutionarily stable if they are honest and condition-dependent or costly to the signaler. One possible cost is the existence of a trade-off between maintaining physiological health and elaboration of ornaments, such that only healthier individuals may afford to produce more elaborate sexual displays. We analyzed the relationship between head coloration and health state of Trachemys scripta elegans turtles. Results showed that turtles with a higher immune response and with a higher body condition had postorbital red patches with brighter coloration with higher values of long-wavelength reflectance (i.e., more reddish). Similarly, turtles with a higher immune response and with a lower heterophil/lymphocyte (H/L) ratio had chin yellow stripes with darker coloration with higher values of medium wavelengths (i.e., more yellowish). These relationships suggest that the health state of T. scripta elegans turtles is reflected by the colorful skin patches and stripes of the head. Characteristics of coloration did not differ between sexes, suggesting that this visual signal may be used by both sexes in intrasexual and intersexual communication. Because many other turtle species have similar colorful patches, it is likely that coloration may have a still unexplored significant role in sexual selection in many turtles.
Morphological adaptations for burrowing, such as an elongated body, and a small head may constrai... more Morphological adaptations for burrowing, such as an elongated body, and a small head may constrain feeding behaviour in fossorial reptiles. We experimentally examined the effect of prey type on prey capture and handling behaviour of the amphisbaenian Blanus cinereus. This amphisbaenian showed four different handling modes according to the characteristics of each prey type. When prey diameter was narrower than gape-size, prey were consumed without prey processing; when prey diameter was wider than gape-size, B. cinereus shifted handling mode to prey processing. Amphisbaenians scraped or tore off bite-sized pieces of large prey and showed longer handling times for some prey types than most epigean saurians. Flexibility in feeding behaviour may allow amphisbaenians to exploit variable underground trophic resources, overcoming constraints of morphological adaptation to fossoriality.
The ecology and behaviour of Amphisbaenians is poorly known due to their fossorial habits. Howeve... more The ecology and behaviour of Amphisbaenians is poorly known due to their fossorial habits. However, amphisbaenians are often found under rocks where they thermoregulate, and probably engage in social interactions. We describe aggregations under rocks in a North African population of the little studied amphisbaenian Trogonophis wiegmanni. These observations could be used to make initial inferences about the social behaviour of this amphisbaenian. Results showed that amphisbaenians were sometimes found in pairs under the same rock. However, these aggregations were not random. Adult males were only found together with adult females, but we did not find pairs of adult males or adult females. This might suggest that there is intra-sexual intolerance, and that adult individuals of the same sex do not occupy the same rock space. Pairs of adults were more frequently found in spring than in autumn, coinciding with the mating season. Also, juvenile individuals were often found together with an adult, but juveniles tended to be more often with an adult female than with an adult male. This might indicate that juveniles are allowed to remain with their parents until they are older, which might enhance offspring fitness by providing access to high-quality habitats.
Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards... more Faeces play a role in intraspecific chemical communication in many vertebrates, including lizards. Here, we hypothesised that juvenile Iberian rock lizards (Lacerta (=Iberolacerta) monticola) use substrate-borne conspecific faecal chemicals to assess the social environment and base their spatial decisions. To test this hypothesis, we prepared chemical stimuli by dissolving faeces in an organic solvent (dichloromethane, DCM) and conducted chemosensory trials where we quantified latency to the first tongue flick (TF) and TF rates when young captive-borne juveniles were placed in an arena compartment whose substrate was labelled by (1) a control (DCM), (2) their own faecal chemicals, (3) faecal chemicals of another juvenile, (4) faecal chemicals of an adult female or (5) faecal chemicals of an adult male. Following TF observations, we removed a partition that separated the labelled compartment from a chemically unlabelled one, and recorded for 5 min when juveniles first crossed to the unlabelled compartment and total time spent in the labelled compartment. Each juvenile was tested with all stimuli in a randomised order. In addition, juveniles belonged to different families and were unrelated to and unfamiliar with faeces donors. Taken together, TF and spatial responses toward stimuli indicate that juveniles discriminated between faecal chemicals of conspecific juveniles, adult females and males, and that they avoided remaining in substrates labelled by adult male faecal chemicals. We suggest that juveniles assess the social environment based on conspecific faecal chemicals thus avoiding aggression and cannibalistic risks undertaken from encounters with adult males.
Uploads
Papers by jose martin