Interpopulational and seasonal variation in the chemical signals of the lizard Gallotia galloti.
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ABSTRACT:
SUBMITTER: Garcia-Roa R
PROVIDER: S-EPMC5721911 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Widespread species often show extensive phenotypic variation due to the contrasting abiotic and biotic factors that shape selective pressures in different environments. In this context, the gradual and predictable patterns of variation in climatic and environmental conditions found in mountain areas offer a great opportunity to explore intraspecific phenotypic variation. For instance, temperature is negatively correlated with altitude and virtually all aspects of the behavior and physiology of ectotherms are sensitive to body temperature. In this work, we tested the hypothesis that morphology, dorsal and ventral coloration and the chemical profile of femoral secretions show interpopulational and seasonal variation in the lacertid lizard (Podarcis liolepis). We compared lizards from three populations inhabiting lowland and highland habitats in the French Pyrenees that were closely related genetically. We found that highland lizards were larger, stockier, had longer heads and more femoral pores and had a darker dorsal coloration than lowland ones. In addition, we detected interpopulational differences in both the abundance and the richness of chemical compounds in the glandular secretions, and we also found seasonal variation in the overall chemical composition. Dorsal and ventral coloration differed seasonally and between populations. Ventral and dorsal brightness were higher in lowland than in highland lizards in the reproductive season whereas the reversed trend was found in the non-reproductive season but only for dorsal brightness. In addition, all lizards had browner dorsal coloration in the non-reproductive season, and lowland lizards were greener in the reproductive season. By integrating information from both visual and chemical systems, our works offers a comprehensive view of how these lizards communicate in a multimodal context.
| S-EPMC6419997 | biostudies-literature
Project description:[This corrects the article DOI: 10.1371/journal.pone.0211686.].
| S-EPMC6464205 | biostudies-literature
Project description:The evolution of chemical signals is subject to environmental constraints. A multicomponent signal may combine semiochemical molecules with supporting compounds able to enhance communication efficacy. Carbonic anhydrases (CAs) are ubiquitous enzymes catalysing the reversible hydration of carbon dioxide, a reaction involved in a variety of physiological processes as it controls the chemical environment of the different tissues or cellular compartments, thus contributing to the overall system homeostasis. CA-IV isoform has been recently identified by mass spectrometry in the femoral gland secretions (FG) of the marine iguana, where it has been hypothesized to contribute to the chemical stability of the signal, by regulating blend pH. Lizards, indeed, use FG to communicate by delivering the waxy secretion on bare substrate, where it is exposed to environmental stressors. Therefore, we expect that some molecules in the mixture may play supporting functions, enhancing the stability of the chemical environment, or even conferring homeostatic properties to the blend. CA-IV may well represent an important candidate to this hypothesized supporting/homeostatic function, and, therefore, we can expect it to be common in FG secretions of other lizard species. To evaluate this prediction and definitely validate CA identity, we analysed FG secretions of eight species of wall lizards (genus Podarcis), combining mass spectrometry, immunoblotting, immunocytochemistry, and transmission electron microscopy. We demonstrate CA-IV to actually occur in the FG of seven out of the eight considered species, providing an immunochemistry validation of mass-spectrometry identifications, and localizing the enzyme within the secretion mass. The predicted structure of the identified CA is compatible with the known enzymatic activity of CA-IV, supporting the hypothesis that CA play a signal homeostasis function and opening to new perspective about the role of proteins in vertebrate chemical communication.
| S-EPMC10465503 | biostudies-literature
Project description:The persistence of colour polymorphism (CP) within a given population is generally associated with the coexistence of alternative reproductive strategies, each one involving specific trade-offs among behavioural, morphological, physiological, and other life histories. Common wall lizard (Podarcis muralis), is a medium-sized diurnal lizard, showing CP in three main colours (yellow, white, and red) on throat and belly, and a morph-specific pattern for both immunocompetence and seasonal variation of T levels. Yellow males show low stamina with high plasma T levels at the beginning of the season, while white males show high stamina with a higher plasma T levels at the end of the season. We hypothesised the presence of two strategies: a risky one, characterised by high aggressiveness played by yellow-morph, and a conservative one by white morph with low aggressiveness. Thus, we tested the aggressive response to conspecifics of yellow and white morphs using a mirror inserted into their cage, mimicking an intrusion of a stranger in their territories, throughout the breeding season (from April to July, 117 trials). We considered three types of aggressive response, with different levels of aggressiveness: (i) bite against the image reflected in the mirror, (ii) seconds spent by the individuals into the half mirrored cage, and (iii) number of times the lizard entered the half mirrored cage. We also considered the number of tongue flicking as explorative behaviour variable. All lizards were tested after a period of acclimatisation to the captivity conditions. Results demonstrate that yellow males showed a higher aggressive response in the early season and a decrease aggressive response towards the end, whereas white males showed an opposite pattern.
| S-EPMC7682419 | biostudies-literature
Project description:Sexual signals used in intraspecific communication are expected to evolve to maximize efficacy under a given climatic condition. Thus, chemical secretions of lizards might evolve in the evolutionary time to ensure that signals are perfectly tuned to local humidity and temperature conditions affecting their volatility and therefore their persistence and transmission through the environment. We tested experimentally whether interpopulational altitudinal differences in chemical composition of femoral gland secretions of male Iberian wall lizards (Podarcis hispanicus) have evolved to maximize efficacy of chemical signals in different environmental conditions. Chemical analyses first showed that the characteristics of chemical signals of male lizards differed between two populations inhabiting environments with different climatic conditions in spite of the fact that these two populations are closely related genetically. We also examined experimentally whether the temporal attenuation of the chemical stimuli depended on simulated climatic conditions. Thus, we used tongue-flick essays to test whether female lizards were able to detect male scent marks maintained under different conditions of temperature and humidity by chemosensory cues alone. Chemosensory tests showed that chemical signals of males had a lower efficacy (i.e. detectability and persistence) when temperature and dryness increase, but that these effects were more detrimental for signals of the highest elevation population, which occupies naturally colder and more humid environments. We suggest that the abiotic environment may cause a selective pressure on the form and expression of sexual chemical signals. Therefore, interpopulational differences in chemical profiles of femoral secretions of male P. hispanicus lizards may reflect adaptation to maximize the efficacy of the chemical signal in different climates.
| S-EPMC4488078 | biostudies-literature
Project description:Understanding what constrains signalling and maintains signal honesty is a central theme in animal communication. Clear cases of dishonest signalling, and the conditions under which they are used, represent an important avenue for improved understanding of animal communication systems. Female mimicry, when certain males take on the appearance of females, is most commonly a male alternative reproductive tactic that is condition-dependent. A number of adaptive explanations for female mimicry have been proposed including avoiding the costs of aggression, gaining an advantage in combat, sneaking copulations with females on the territories of other males, gaining physiological benefits and minimizing the risk of predation. Previous studies of female mimicry have focused on a single mode of communication, although most animals communicate using multiple signals. Male Augrabies flat lizards adopt alternative reproductive tactics in which some males (she-males) mimic the visual appearance of females. We experimentally tested in a wild population whether she-males are able to mimic females using both visual and chemical signals. We tested chemical recognition in the field by removing scent and relabelling females and she-males with either male or female scent. At a distance, typical males (he-males) could not distinguish she-males from females using visual signals, but during close encounters, he-males correctly determined the gender of she-males using chemical signals. She-males are therefore able to deceive he-males using visual but not chemical signals. To effectively deceive he-males, she-males avoid close contact with he-males during which chemical cues would reveal their deceit. This strategy is probably adaptive, because he-males are aggressive and territorial; by mimicking females, she-males are able to move about freely and gain access to females on the territories of resident males.
| S-EPMC2660994 | biostudies-literature
Project description:Important part of the multivariate selection shaping social and interspecific interactions among and within animal species emerges from communication. Therefore, understanding the diversification of signals for animal communication is a central endeavor in evolutionary biology. Over the last decade, the rapid development of phylogenetic approaches has promoted a stream of studies investigating evolution of communication signals. However, comparative research has primarily focused on visual and acoustic signals, while the evolution of chemical signals remains largely unstudied. An increasing interest in understanding the evolution of chemical communication has been inspired by the realization that chemical signals underlie some of the major interaction channels in a wide range of organisms. In lizards, in particular, chemosignals play paramount roles in female choice and male-male competition, and during community assembly and speciation. Here, using phylogenetic macro-evolutionary modeling, we show for the very first time that multiple compounds of scents for communication in lizards have diversified following highly different evolutionary speeds and trajectories. Our results suggest that cholesterol, α-tocopherol, and cholesta-5,7-dien-3-ol have been subject to stabilizing selection (Ornstein-Uhlenbeck model), whereas the remaining compounds are better described by Brownian motion modes of evolution. Additionally, the diversification of the individual compounds has accumulated substantial relative disparity over time. Thus, our study reveals that the chemical components of lizard chemosignals have proliferated across different species following compound-specific directions.
| S-EPMC5306189 | biostudies-literature
Project description:PoolSeq analysis of seasonal variation in a natural population of the non-biting midge Chironomus riparius
| PRJEB35534 | ENA
Project description:BackgroundThe giant lizard of La Gomera (Gallotia bravoana), is an endemic lacertid of this Canary Island that lives confined to a very restricted area of occupancy in a steep cliff, and is catalogued as Critically Endangered by IUCN. We present the first population genetic analysis of the wild population as well as of captive-born individuals (for which paternity data are available) from a recovery center. Current genetic variability, and inferred past demographic changes were determined in order to discern the relative contribution of natural versus human-mediated effects on the observed decline in population size.ResultsGenetic analyses indicate that the only known natural population of the species shows low genetic diversity and acts as a single evolutionary unit. Demographic analyses inferred a prolonged decline of the species for at least 230 generations. Depending on the assumed generation time, the onset of the decline was dated between 1200-13000 years ago. Pedigree analyses of captive individuals suggest that reproductive behavior of the giant lizard of La Gomera may include polyandry, multiple paternity and female long-term sperm retention.ConclusionsThe current low genetic diversity of G. bravoana is the result of a long-term gradual decline. Because generation time is unknown in this lizard and estimates had large credibility intervals, it is not possible to determine the relative contribution of humans in the collapse of the population. Shorter generation times would favor a stronger influence of human pressure whereas longer generation times would favor a climate-induced origin of the decline. In any case, our analyses show that the wild population has survived for a long period of time with low levels of genetic diversity and a small effective population size. Reproductive behavior may have acted as an important inbreeding avoidance mechanism allowing the species to elude extinction. Overall, our results suggest that the species retains its adaptive potential and could restore its ancient genetic diversity under favorable conditions. Therefore, management of the giant lizard of La Gomera should concentrate efforts on enhancing population growth rates through captive breeding of the species as well as on restoring the carrying capacity of its natural habitat.
| S-EPMC4254221 | biostudies-literature
Project description:Environmental heterogeneity on a spatial and temporal scale fosters an organism's capacity to plastically alter coloration. Predation risk might favour the evolution of phenotypic plasticity in colour patterns, as individuals who change colour throughout the year may be able to improve their fitness. Here we explored the change in dorsal pigmentation of the Italian wall lizard (Podarcis siculus campestris) at three time points (March, July, October) during a period of activity in a Mediterranean natural area in southern Italy. Following a preliminary investigation conducted in 2018, during 2019 we captured 135 lizards and took a picture of their ventral scales to check for possible recapture over the sessions. Lizard dorsal pictures were collected in the field with the support of a reference chart to quantitatively estimate chromatic variables (hue, saturation and value). At the same time, pictures of the environmental background were collected. Our findings suggest that lizards are capable of altering dorsal coloration during seasonal change. They vary from green at the onset of spring, to brownish in the middle of summer and to a greyish colour in October. This modification closely followed environmental background colour variation and enhanced lizard crypsis during each season.
| S-EPMC7286296 | biostudies-literature