Browsing by Author "Clavijo-Baquet, Sabrina"

Now showing 1 - 4 of 4
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    Daily and Seasonal Basking Behavior in Two South American Freshwater Turtles, Trachemys dorbigni and Phrynops hilarii
    (2017) Clavijo-Baquet, Sabrina; Magnone, Larisa
    Many species of reptiles maintain their body temperature behaviorally in a narrow range, even in the presence of considerable environmental temperature variation, by choosing microhabitats with different temperatures. In freshwater turtles, thermoregulation is generally achieved by aerial basking, even though they perform all other vital activities such as food consumption and reproduction in the water. Therefore, time budgets related to basking should be constrained and individuals should maximize the energy per unit time during basking, potentially by increasing basking frequency at noon during colder months and increasing use of basking when water temperature decreases. We analyzed basking behavior during the austral summer to study the effects of season, water temperature, and time of day in 2 South American freshwater turtles: Trachemys dorbigni (black-bellied slider) and Phrynops hilarii (Hilaire's side-necked turtle). We found that water temperature negatively affected basking frequency in both species differently; basking by T. dorbigni occurred on a diel cycle while basking by P. hilarii occurred on a seasonal level. Both species showed a bell-shaped basking frequency during the day, with more individuals basking at noon than in the morning and afternoon. However, only P. hilarii showed a significant seasonal effect on basking, with basking frequency decreasing in summer. These results suggest the thermoregulatory role of basking behavior in 2 austral turtle species and its trade-off with other vital activities.
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    How do ectotherms perform in cold environments? Physiological and life-history traits in an Andean viviparous lizard
    (2022) Clavijo-Baquet, Sabrina; Orellana, Maria J.; Sabat, Pablo; Bozinovic, Francisco
    Both the mean and the variation in environmental temperature are increasing globally. Indeed, the predicted increases in temperature range from 2 to 4 degrees C in the next 50 years. Ectotherms control body temperature by means of behavior selecting microsites with different temperatures, which makes them more susceptible to changes in climate. Nevertheless, lizards living in high mountain environments have developed several mechanisms to inhabit and colonize variable environments with extreme temperatures. These mechanisms include a high metabolism to be active at lower temperatures and viviparity to improve embryonic development. Despite behavioral thermoregulation acting as a buffer to changes in environmental temperature, other traits such as life-history traits may be less flexible. Consequently, in an attempt to understand how lizards cope with harsh habitats, we evaluated some physiological traits and responses of females of Liolaemus bellii from two contrasting slope sites with differences in environmental temperature and humidity, but at the same altitude in the southern Andes range. We collected pregnant females from opposite slopes and maintained them until parturition in a common-garden experiment. Females from the south-facing slope (S-slope) had higher preferred body temperature (T-pref) values before and after parturition and exhibited higher daily energy expenditure before parturition. Nevertheless, no difference in T-pref was shown by their offspring, suggesting a developmental plastic response or adaptation to lower environmental temperature. For instance, the higher metabolism during pregnancy could be associated with a shorter activity period on the snowy S-slope. Additionally, females from the S-slope had larger kidneys and gave birth later than N-slope females, likely due to developmental plasticity or genetic differentiation. How fixed these traits are, in individuals from the contrasting slopes, will determine the response capacity of the L. bellii population to climate change.
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    Influence of temperature variability on the feeding behavior and blood consumption of Triatoma infestans (Hemiptera: Reduviidae)
    (2024) Alvarez-Duhart, Barbara; Cavieres, Grisel; Gonzalez, Avia; Cattan, Pedro E.; Bozinovic, Francisco; Clavijo-Baquet, Sabrina
    The transmission and incidence of vector-borne diseases rely on vector distribution and life history traits such as survival, fecundity, and feeding. Since arthropod disease vectors are ectotherms, these vital rates are strongly influenced by temperature. Chagas disease is a neglected tropical disease caused by the protozoan parasite, Trypanosoma cruzi. This parasite is transmitted when the feces of the infected triatomine enter the bloodstream of the host. One of the most important vector-species of this disease in the Southern Cone region of South America is Triatoma infestans. In this study, we evaluated the role of constant and variable environmental temperature on the feeding behavior of T. infestans. Fifth-instar nymphs were acclimatized to 4 thermal treatments comprising 2 temperatures (27 degrees C and 18 degrees C) with and without diurnal thermal variability (27 +/- 5 degrees C and 18 +/- 5 degrees C). Individuals were fed weekly for 7 wk to quantify their feeding. Our results showed lower feeding frequency in nymphs acclimatized to cold temperature compared to those from warmer temperature treatments. However, treatments with thermal variability presented a nonlinear effect on feeding, with an increased feeding rate in the cold, variable treatment and a decreased feeding rate in the warm, variable treatment. Individuals maintained under cold treatments, the variable temperature exhibited a higher feeding rate and the lowest amount of ingested blood among all treatments. Thus, natural diurnal temperature variation cannot be ignored if we are to make more accurate T. cruzi transmission risk predictions now and in the future.
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    Thermal performance of the Chagas disease vector, Triatoma infestans, under thermal variability
    (2021) Clavijo-Baquet, Sabrina; Cavieres, Grisel; Gonzalez, Avia; Cattan, Pedro E.; Bozinovic, Francisco
    Vector-borne diseases (VBD) are particularly susceptible to climate change because most of the diseases' vectors are ectotherms, which themselves are susceptible to thermal changes. The Chagas disease is one neglected tropical disease caused by the protozoan parasite, Trypanosoma cruzi. One of the main vectors of the Chagas disease in South America is Triatoma infestans, a species traditionally considered to be restricted to domestic or peridomestic habitats, but sylvatic foci have also been described along its distribution. The infestation of wild individuals, together with the projections of environmental changes due to global warming, urge the need to understand the relationship between temperature and the vector's performance. Here, we evaluated the impact of temperature variability on the thermal response of T. infestans. We acclimated individuals to six thermal treatments for five weeks to then estimate their thermal performance curves (TPCs) by measuring the walking speed of the individuals. We found that the TPCs varied with thermal acclimation and body mass. Individuals acclimated to a low and variable ambient temperature (18 degrees C +/- 5 degrees C) exhibited lower performances than those individuals acclimated to an optimal temperature (27 degrees C +/- 0 degrees C); while those individuals acclimated to a low but constant temperature (18 degrees C +/- 0 degrees C) did not differ in their maximal performance from those at an optimal temperature. Additionally, thermal variability (i.e., +/- 5 degrees C) at a high temperature (30 degrees C) increased performance. These results evidenced the plastic response of T. infestans to thermal acclimation. This plastic response and the non-linear effect of thermal variability on the performance of T. infestans posit challenges when predicting changes in the vector's distribution range under climate change.