Browsing by Author "Vidal, Marcela A."

Now showing 1 - 6 of 6
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    Amphibian phylogenetic diversity in the face of future climate change: not so good news for the chilean biodiversity hotspot
    (2022) Rodriguez, Leonardo J.; Barbosa, Olga A.; Soto-Azat, Claudio; Alvarado-Rybak, Mario; Correa, Claudio; Mendez, Marco A.; Moreno-Gomez, Felipe N.; Rabanal, Felipe E.; Vidal, Marcela A.; Velasquez, Nelson A.; Bacigalupe, Leonardo D.
    Climate change is projected to be the most extensive human-induced disturbance to occur on natural ecosystems, inducing changes in different biodiversity features including the evolutionary history of a region through the decline and loss of its phylogenetic diversity. Amphibians, given their ectothermic life cycle and critical conservation status, would potentially be exposed to extinction processes under conditions of climate change, with the corresponding loss of evolutionary history in regions of high biodiversity. This research addresses the effects of climate change on the evolutionary history of amphibians in the Chilean Biodiversity Hotspot, by estimating the PD (Phylogenetic diversity) and PE (Phylogenetic endemism) of 27 species. Using different RCP (RCP 4.5 and 8.5) and time frames (years 2050 and 2070), we create species distribution models (SDM) to evaluate the species range dynamics and the phylodiversity in the Hotspot. Also, given that Protected Areas (PA) are the main global strategy to ensure the conservation of species and their features, we evaluate the capacity of PA to conserve the evolutionary history in the Hotspot. Our results show a set of modeled species that will become extinct, or will experiment changes in their distributional ranges, inducing a clear decline of amphibian evolutionary history for the next 30 to 50 years, and a worrying low capacity of the PA to contain current and future PD and PE. Given the critical amphibian scenario, our results highlight the need for further research to improve the decision-making process in the hotspot area addressing the potential amphibian extinction risk, the lack of protection by the PA system, and the loss of evolutionary history as a key aspect of biodiversity.
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    Distribution, conservation assessment and management perspectives of Chilean micro-snails of the family Charopidae
    (2023) Collado, Gonzalo A.; Flores, Nataly; Vidal, Marcela A.; Torres-Diaz, Cristian; Valladares, Moises A.
    The biodiversity of molluscs is highly threatened in marine, terrestrial and freshwater ecosystems worldwide. This research aimed at studying the distribution and conservation status of eight poorly-known micro-snails of the genera Stephacharopa and Stephadiscus in Chile. We performed a comprehensive review of literature and databases to determine the occurrences of the species, which were mapped on vector layers containing protected areas and human development infrastructure to find potential threats. Conservation status assessment was performed following the criteria and tools implemented by the International Union for the Conservation of Nature (IUCN) Red List and NatureServe. We also conducted species distribution models, based on maximum entropy, to identify areas that should be prioritised for conservation. Two species meet the criteria for IUCN listing as Critically Endangered (CR), four Endangered (EN), one Vulnerable (Vu) and one Least Concern (LC). This classification is rather coincident with equivalent categories obtained under the NatureServe standard, in which two species were ranked as Critically Imperiled (N1), five Imperiled (N2) and one Vulnerable (N3). We found that Stephacharopa paposensis is the most at-risk species, with only one occurrence not included in a protected area, followed by Stephadiscus stuardoi, with two occurrences, one of them within a protected area. Stephadiscus lyratus was the species with the greatest geographic range, accounting for 17 occurrences, seven matching a protected area. We found wider potential ranges in modelled species that may be useful for prioritising conservation measures. Considering distributional data, protected areas and more than 20 plausible threats identified, we propose potential in situ and ex situ conservation actions to protect these neglected micro-snails.
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    Intra and interspecific variation in thermal performance and critical limits in anurans from southern Chile
    (2024) Vidal, Marcela A.; Rezende, Enrico L.; Bacigalupe, Leonardo D.
    The relationship between temperature and performance can be illustrated through a thermal performance curve (TPC), which has proven useful in describing various aspects of ectotherms' thermal ecology and evolution. The parameters of the TPC can vary geographically due to large-scale variations in environmental conditions. However, only some studies have attempted to quantify how thermal performance varies over relatively small spatial scales, even in the same location or consistently among individuals within a species. Here, we quantified individual and species variation in thermal sensitivity of locomotor performance in five amphibia Eupsophus species found in the temperate rainforests of southern Chile and compared their estimates against co-occurring species that exhibit a substantially more extensive distributional range. We measured critical thermal limits and jumping performance under five different temperatures. Our results suggest that thermal responses are relatively conserved along the phylogeny, as the locomotor performance and thermal windows for activity remained narrow in Eupsophus species when compared against results observed for Batrachyla taeniata and Rhinella spinulosa. Additionally, we found significant individual differences in locomotor performance within most species, with individual consistency in performance observed across varied temperatures. Further analyses explored the influence of body size on locomotor performance and critical thermal limits within and between species. Our results suggest a trade-off scenario between thermal tolerance breadth and locomotor performance, where species exhibiting broader thermal ranges might have compromised performance. Interestingly, these traits seem partly mediated by body size variations, raising questions about potential ecological implications.
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    Seasonal and geographic variation in thermal biology of the lizard Microlophus atacamensis (Squamata: Tropiduridae)
    (2008) Sepulveda, Maritza; Vidal, Marcela A.; Farina, Jose M.; Sabat, Pablo
    1. We studied physiological thermal adaptation in the lizard Microlophus atacamensis along a latitudinal range.
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    Stable isotopes document mainland-island divergence in resource use without concomitant physiological changes in the lizard Liolaemus pictus
    (2010) Vidal, Marcela A.; Sabat, Pablo
    Shifts in feeding ecology are believed to promote island-mainland divergence. The lizard Liolaemus pictus has several different subspecies on Chilean islands and mainland. These subspecies inhabit contrastingly different habitats both in different islands and mainland, which suggests the potential for habitat related dietary variation. We investigated the dietary habits of L. pictus by both stomach content analyses and by nitrogen stable isotope analyses (delta N-15), which we used as a proxy variable for trophic level. We also compared the morphology of the digestive tract and the activity of intestinal digestive enzymes of mainland and island lizards. We hypothesized differences in diet and trophic level among populations and that these differences would predict the expression of the morphological and biochemical features of the digestive tract. More specifically, we predicted shorter intestines and higher levels of peptidases in more insectivorous than in more frugivorous/herbivorous lizards. The diet of L. pictus was characterized by the consumption of a wide diversity of food types, including fruit and insects, in all populations. Stable isotopes revealed higher trophic level, and hence probably higher protein intake, in mainland than in island populations, but contrary to our prediction, they had shorter intestines and higher relative activity of intestinal peptidases than mainland lizards. Furthermore, the proportion of fruit items in the stomach content was higher in the population that exhibited the lowest tropic level. These results suggest that morphological and physiological differences among populations of L. pictus are not correlated with feeding ecology, suggesting that the lizard's first responses to the selective pressure represented by a diet shift are behavioral. (C) 2010 Elsevier Inc. All rights reserved.
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    Thermoregulation and activity pattern of the high-mountain lizard Phymaturus palluma (Tropiduridae) in Chile
    (2010) Vidal, Marcela A.; Habit, Evelyn; Victorian, Pedro; Gonzalez-Gajardo, Angelica; Ortiz, Juan C.
    Behavioral and physiological mechanisms of thermoregulation in ectotherms are conditioned by thermal constraints. These mechanisms may be even more restrictive when environmental conditions are unfavorable for individuals, especially when sexual dimorphism segregates the sexes spatially. In order to understand behavioral and physiological regulation mechanisms, we investigated the thermal biology of Phymaturus palluma (Molina, 1782), a sexually size dimorphic, high-mountain lizard that inhabits extreme climatic conditions. P. palluma showed a bimodal activity pattern, a major peak in the morning (11:00-13:30h) and in the afternoon (15:30-18:00 h). The lizards were more active when substrate temperatures were between 25 and 28 degrees C. The highest abundance was found around 27 degrees C (between 11:00-12:30). Females showed greater activity than males in the early morning. Sub-adults and juveniles did not show differences in their activity pattern. There was a positive relationship between body temperature and air and substrate temperatures, suggesting typically thigmothermal regulation.