Margarita Chiaraviglio - Academia.edu (original) (raw)

Papers by Margarita Chiaraviglio

Herpetological Monographs, 2006

ABSTRACT Various hypotheses suggest that the benefit of viviparity lays in the acquisition of an ... more ABSTRACT Various hypotheses suggest that the benefit of viviparity lays in the acquisition of an appropriate range of temperatures during incubation, as this phenomenon has evolved from egg laying in many lineages of lizards and snakes, apparently in response to extreme climates. I examined the effects of reproductive condition on thermoregulation in the Argentina boa constrictor (Boa constrictor occidentalis) to offer an insight into the selective forces acting on the critical phase of its life history. Thermal ecology and activity during the mating season were investigated using radiotelemetry. A differential thermoregulatory behavior was manifested. Body temperatures of reproductive females were significantly higher than those of both reproductive males and non reproductive females. Regression analysis showed that reproductive females had a lower slope and a higher Y-intercept than reproductive males and non reproductive females, suggesting that the reproductive females are better thermoregulators.

Cuadernos de Herpetología, 2012

Through the participation of nine specialists from different institutions from all over Argentina... more Through the participation of nine specialists from different institutions from all over Argentina and after more than a decade from the first Red List of threatened herpetofauna proposed by Asociacion Herpetologica Argentina in 2000, we assessed the conservation status of the argentine Testudines taxa, adding the new taxonomic, biological and ecological knowledge progresses made since then as well as applying methodological changes in the former assessment. As a result from the 14 turtles taxa recognized as present in Argentina, nine were included in the actual Red List under some degree of risk (three Critically Endangered, three Endangered, three Vulnerable). From the remaining ones, three were classified as Insufficiently Known and two as Not Threatened. In the classification of the three marine turtles that are frequently found in argentine coasts we adopted the IUCN (2011) Red List criteria. In relation with the former categorization, we included a new species registered in Arg...

Biological Journal of the Linnean Society

Bite force in lizards is involved in key behaviours such as intrasexual agonistic and intersexual... more Bite force in lizards is involved in key behaviours such as intrasexual agonistic and intersexual interactions. The relationship between morphology and function is dynamic and sexual pressures can affect bite performance differently between sexes, especially considering the biting position and temporal changes related to the reproductive cycle. The Achala copper lizard (Pristidactylus achalensis) is a highly dimorphic lizard with a short reproductive season. Both sexes present bite scars; however, scar position varies between sexes implying different bite functions. We studied factors influencing bite force such as sex, body size, head morphology and seasonality. We also compared the maximum bite force at two biting positions (frontal and lateral) related to different behaviours (copulation and fighting), and quantified the incidence and scar pattern between sexes. Overall, males bite harder than females and lateral bites were harder than frontal ones. Although bite force did not va...

En el Aula Virtual de Biologia del Comportamiento, de la Universidad Nacional de Cordoba, se prop... more En el Aula Virtual de Biologia del Comportamiento, de la Universidad Nacional de Cordoba, se propone a los estudiantes el abordaje de los metodos de muestreo del comportamiento inmerso en la problematica de la agresion en la sociedad humana. El Aula Virtual pretende motivar un proceso de aprendizaje a nivel conceptual, procedimental y actitudinal. En este trabajo queremos presentar y reflexionar sobre la experiencia educativa de nivel universitario desarrollada en el Aula Virtual. Se detallan consideraciones metodologicas referidas a las consignas propuestas a los estudiantes y se resumen los principales resultados. Como conclusion podemos decir que, el Aula Virtual es una poderosa herramienta que contempla a los estudiantes universitarios como sujetos activos, constructivos, y reflexivos. Ademas, creemos que este trabajo practico tiene un gran valor social, ya que una fortaleza como sociedad seria comprender nuestros comportamientos y transformar nuestras actitudes agresivas en ac...

Considerando la importancia del cambio conceptual, nuestro proposito es acercarnos al analisis de... more Considerando la importancia del cambio conceptual, nuestro proposito es acercarnos al analisis de los procesos de aprendizaje experimentados por los estudiantes universitarios, y ahondar en como generar ese proceso de cambio. En el presente trabajo nos planteamos como objetivo analizar la herramienta pedagogica del Aula Virtual de nivel universitario como motivadora del cambio conceptual en el dominio de la Biologia del Comportamiento. Nuestro modelo pedagogico se sostiene en el convencimiento que los conocimientos no son acabados, por lo tanto el proposito de nuestra Aula Virtual es que los estudiantes interpreten y discutan diferentes teorias vigentes y establecidas en la comunidad cientifica y contrasten nuevas teorias que plantean controversias a lo establecido. Se detallan consideraciones metodologicas referidas a las consignas propuestas a los estudiantes y se resumen los principales resultados. Como conclusion, consideramos que la actividad del Aula Virtual satisface ampliam...

Biological Journal of the Linnean Society, 2020

Phenotype in lizards is related to reproductive function, and hence to reproductive output. Besid... more Phenotype in lizards is related to reproductive function, and hence to reproductive output. Besides the intraspecific diversity in phenotypes, their temporal variation throughout the reproductive season in relation to the variation of social contexts builds extra complexity into sexual selection scenarios. One useful model for understanding phenotypic diversity dynamics is Tropidurus spinulosus because it presents sexual dimorphism in different phenotypic traits, dichromatism in regions related to reproductive behaviour, and it has intense social reproductive interactions. We aimed to evaluate how the reproductive and phenotypic traits of individuals vary with changing social contexts, and how intrasexual phenotypic diversity and reproductive potential are explained by the phenotypic traits. In this study, we used data obtained during four consecutive breeding seasons (2015–2018) in a wild population. The social context, characterized according to the operational sex ratio, varied b...

Canadian Journal of Zoology, 2020

The intensity of mating competition varies according to the temporal and spatial distribution of ... more The intensity of mating competition varies according to the temporal and spatial distribution of individuals. Measuring sexual dimorphism over time and interpreting the association between individuals is therefore important if we aim to understand how sexual traits are influenced. We examined sex differences in the Achala Copper Lizard (Pristidactylus achalensis (Gallardo, 1964)), an endemic species from the highest part of mountains of central Argentina. Over 4 years, we explored sex-specific variation in body size, head size, interlimb length, and body colouration. Furthermore, we evaluated how these traits varied temporally, and we also explored whether the spatial distribution of individuals is explained by variation in these traits. We found that P. achalensis is a species with sexual dimorphism in multiple characters, including body size, head size, and colouration. Interestingly, some traits related to mating, such as head width, show a temporal variability in both sexes, whe...

Scientific Reports, 2019

Colors are important vehicles for social signals in many taxa. In Squamata, previous studies have... more Colors are important vehicles for social signals in many taxa. In Squamata, previous studies have linked color characteristics and chromatic diversity to sexual selection and, particularly, species showing male-biased body size dimorphism also showed male-biased dichromatism and color diversity. Sexual dichromatism may occur in body regions used for conspecific communication and it may be expressed at wavelengths, such as ultraviolet, easily perceivable by conspecifics. We tested this prediction in a social lizard model, Tropidurus spinulosus, using spectrophotometry and visual modelling which enable colors to be interpreted as the individuals of the same taxon see them. Our results indicate that sexual dichromatism occurs in the ventral regions and the flanks, which are the body regions involved in sexual displays. Males show greater color diversity, having larger color volumes and more contrasting colors. These findings reinforce the idea that sexual selection towards males is cou...

BMC Evolutionary Biology, 2018

Background: Comparing sexual size dimorphism (SSD) in the light of the phylogenetic hypothesis ma... more Background: Comparing sexual size dimorphism (SSD) in the light of the phylogenetic hypothesis may help to understand the phenotypic evolution associated with sexual selection (size of whole body and of reproductionrelated body parts). Within a macroevolutionary framework, we evaluated the association between the evolution of SSD and the evolution of reproduction-related phenotypic traits, and whether this association has favored female fecundity, considering also variations according to reproductive modes. We focused on the lizard species that inhabit the Chaco Domain since this is a natural unit with a high diversity of species. Results: The residual SSD was related positively with the residuals of the reproduction-related phenotypic traits that estimate intrasexual selection and with the residuals of inter-limb length and, according to fecundity selection, those residuals were related positively with the residuals of clutch size in oviparous species. Lizards of the Chaco Domain present a high diversity of SSD patterns, probably related to the evolution of reproductive strategies. Conclusions: Our findings highlight that the sexual selection may have acted on the whole-body size as well as on the size of body parts related to reproduction. Male and female phenotypes evolutionarily respond to variations in SSD, and an understanding of these patterns is essential for elucidating the processes shaping sexual phenotype diversity from a macroevolutionary perspective.

Journal of thermal biology, 2018

Reproduction is an energetically costly activity that can alter thermal requirements in Squamata.... more Reproduction is an energetically costly activity that can alter thermal requirements in Squamata. This phenomenon has been largely studied in many viviparous species; however, little is known about the role of oviparous females in controlling temperature during vitellogenesis and embryo development before oviposition. Diversity of female phenotypes could be associated with diversity of thermoregulatory performance, since thermal requirements are frequently influenced by body shape. Furthermore, studying the thermoregulatory behaviour is fundamental to understand how females regulate their body temperature. Here, we aimed to determine whether reproduction alters thermal requirements in an oviparous model, Tropidurus spinulosus, and if the preferred body temperature and thermoregulatory behaviour vary among reproductive stages and in relation to the female phenotype. We characterized the female phenotypes according to multiple morphological traits (snout-vent length, inter-axillar len...

Theriogenology, Jan 15, 2018

The development of safe and consistent semen collection protocols should be ensured to understand... more The development of safe and consistent semen collection protocols should be ensured to understand basic sperm parameters of a species. Electroejaculation has been hypothesized and tested to be a safe method to evaluate male reproductive potential in wild animals. However, little is known about semen collection protocols in lizards. Adjusting stimulation to species and body mass is important for efficient semen collection as well as for animal welfare. Tropidurus spinulosus is a good model to adapt electrostimulation; it is a medium-sized lizard species, males have semen during a long period and operative sex ratio is male-biased. We aimed to provide a thorough and safe method for collecting semen samples from this animal model by means of electrostimulation and characterize basic sperm parameters. Mature males of T. spinulosus were captured and their testicular volume was evaluated via portable ultrasound scanning. The lizards were electrostimulated by performing standardized series...

Biological Journal of the Linnean Society, 2016

Understanding pre-and post-copulatory mechanisms of sexual selection can provide insights into th... more Understanding pre-and post-copulatory mechanisms of sexual selection can provide insights into the evolution of male reproductive strategies. The phenotype-linked fertility hypothesis postulates that male sperm quality and secondary sexual characteristics will positively co-vary, whereas the sperm competition hypothesis predicts a negative association between those traits. Male reproductive traits often show variation throughout the reproductive period, suggesting that the relationship between pre-and post-copulatory sexual selection may vary temporally. Here, we evaluated the relationship between secondary sexual character and sperm traits and its temporal variation in Salvator rufescens, a south American lizard. We observed a negative relationship between jaw muscle and principal piece length of sperm and a variation in the relationship between pre-and post-copulatory traits throughout the reproductive period. Collectively, our results evidenced a trade-off between pre-and post-copulatory traits and a strong seasonal flexibility of male reproductive strategies in this lizard species.

Cuadernos De Herpetologia, 1999

Scientifica, 2016

The reproductive traits of males are under influence of sexual pressures before and after copulat... more The reproductive traits of males are under influence of sexual pressures before and after copulation. The strength of sexual selection varies across populations because they undergo varying competition for mating opportunities. Besides intraspecific pressures, individuals seem to be subjected to pressures driven by interspecific interactions in sympatry. Lizards may vary their reproductive strategies through varying sexual characters, body size, gonadal investment, and sperm traits. We evaluated the reproductive traits, involved in pre- and postcopulatory competition, in allopatric and sympatric populations ofSalvatorlizards. We observed a spatial gradient of male competition among populations, with the following order: allopatric zone ofS. rufescens; sympatric zone; and allopatric zone ofS. merianae. Accordingly, variation in secondary sexual character, the relative testis mass, and the length of sperm component was observed between allopatry and sympatry in each species, suggestin...

Wildlife Research, 2015

Context Management of the exploitation of resources requires biological information on exploited ... more Context Management of the exploitation of resources requires biological information on exploited species. The skins of large reptiles have a commercial value as luxury leather items and Tupinambis lizards from southern South America have historically been exploited for this purpose. Argentina implemented management plans for Tupinambis lizards since 1988 that established a minimum capture size based on the width of dried skins, but this prescription has not been linked to local reproductive attributes of species. Aim In this study, we aim to determine the reproductive parameters of Tupinambis merianae and evaluate which class sizes of individuals are susceptible to commercial trade in central Argentina to generate local and species-specific information to improve available management tools. Methods We determined the relationship between the width of dried skins and live body sizes. We identified size at sexual maturity in males and females. Moreover, we determined status of reproduc...

Annales Zoologici Fennici, 2015

ABSTRACT A major goal in evolutionary biology is to determine the mechanisms responsible for main... more ABSTRACT A major goal in evolutionary biology is to determine the mechanisms responsible for maintaining phenotypic variation. Species that have evolved intersexual differences provide an opportunity to increase our understanding of trait evolution. We hypothesize that phenotypic diversity is related to reproductive strategies of female lizards and therefore, to their reproductive potential. Consequently, we evaluated sexual dimorphism in several morphological traits and assessed phenotypic variability and selection on body traits of female lizards in a model species (Tupinambis merianae). The results support our hypothesis that certain phenotypic traits of body shape are sexually dimorphic and that females present large continuous variation in these traits. Moreover, some morphological traits in females favor the increment of energetic reserves and reproductive output. These results contribute to the identification of characters upon which selection may have acted and suggest that phenotypic variation in female lizards are related to a diversity of reproductive strategies. Therefore, we fill part of the knowledge gap on the proximate mechanisms that link maternal morphology and reproductive potential in female lizards.

Annales Zoologici Fennici, 2014