DSpace Angular :: Browsing by Author "Bozinovic, Francisco"

Browsing by Author "Bozinovic, Francisco"

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A Mesocosm Experiment in Ecological Physiology: The Modulation of Energy Budget in a Hibernating Marsupial under Chronic Caloric Restriction
(2022) Nespolo, Roberto F.; Fonturbel, Francisco E.; Mejias, Carlos; Contreras, Rodrigo; Gutierrez, Paulina; Oda, Esteban; Sabat, Pablo; Hambly, Catherine; Speakman, John R.; Bozinovic, Francisco
During the past 60 years, mammalian hibernation (i.e., seasonal torpor) has been interpreted as a physiological adaptation for energy economy. However, direct field comparisons of energy expenditure and torpor use in hibernating and active free-ranging animals are scarce. Here, we followed the complete hibernation cycle of a fat-storing hibernator, the marsupial Dromiciops gliroides, in its natural habitat. Using replicated mesocosms, we experimentally manipulated energy availability and measured torpor use, hibernacula use, and social clustering throughout the entire hibernation season. Also, we measured energy flow using daily food intake, daily energy expenditure (DEE), and basal metabolic rate (BMR) in winter. We hypothesized that when facing chronic caloric restriction (CCR), a hibernator should maximize torpor frequency to compensate for the energetic deficit, compared with individuals fed ad lib. (controls). However, being torpid at low temperatures could increase other burdens (e.g., cost of rewarming, freezing risks). Our results revealed that CCR animals, compared with control animals, did not promote heat conservation strategies (i.e., clustering and hibernacula use). Instead, they gradually increased torpor frequency and reduced DEE and, as a consequence, recovered weight at the end of the season. Also, CCR animals consumed food at a rate of 50.8 kJ d(-1), whereas control animals consumed food at a rate of 98.4 kJ d(-1). Similarly, the DEE of CCR animals in winter was 47.3 & PLUSMN;5.64 kJ d(-1), which was significantly lower than control animals (DEE=88.0 & PLUSMN;5.84 kJ d(-1)). However, BMR and lean mass of CCR and control animals did not vary significantly, suggesting that animals maintained full metabolic capacities. This study shows that the use of torpor can be modulated depending on energy supply, thus optimizing energy budgeting. This plasticity in the use of heterothermy as an energy-saving strategy would explain the occurrence of this marsupial in a broad latitudinal and altitudinal range. Overall, this study suggests that hibernation is a powerful strategy to modulate energy expenditure in mammals from temperate regions.
A Multivariate Assessment of Age-Related Cognitive Impairment in Octodon degus
(2021) Rivera, Daniela S.; Lindsay, Carolina B.; Oliva, Carolina A.; Bozinovic, Francisco; Inestrosa, Nibaldo C.
Aging is a progressive functional decline characterized by a gradual deterioration in physiological function and behavior. The most important age-related change in cognitive function is decline in cognitive performance (i.e., the processing or transformation of information to make decisions that includes speed of processing, working memory, and learning). The purpose of this study is to outline the changes in age-related cognitive performance (i.e., short-term recognition memory and long-term learning and memory) in long-lived Octodon degus. The strong similarity between degus and humans in social, metabolic, biochemical, and cognitive aspects makes it a unique animal model for exploring the mechanisms underlying the behavioral and cognitive deficits related to natural aging. In this study, we examined young adult female degus (12- and 24-months-old) and aged female degus (38-, 56-, and 75-months-old) that were exposed to a battery of cognitive-behavioral tests. Multivariate analyses of data from the Social Interaction test or Novel Object/Local Recognition (to measure short-term recognition memory), and the Barnes maze test (to measure long-term learning and memory) revealed a consistent pattern. Young animals formed a separate group of aged degus for both short- and long-term memories. The association between the first component of the principal component analysis (PCA) from short-term memory with the first component of the PCA from long-term memory showed a significant negative correlation. This suggests age-dependent differences in both memories, with the aged degus having higher values of long-term memory ability but poor short-term recognition memory, whereas in the young degus an opposite pattern was found. Approximately 5% of the young and 80% of the aged degus showed an impaired short-term recognition memory; whereas for long-term memory about 32% of the young degus and 57% of the aged degus showed decreased performance on the Barnes maze test. Throughout this study, we outlined age-dependent cognitive performance decline during natural aging in degus. Moreover, we also demonstrated that the use of a multivariate approach let us explore and visualize complex behavioral variables, and identified specific behavioral patterns that allowed us to make powerful conclusions that will facilitate further the study on the biology of aging. In addition, this study could help predict the onset of the aging process based on behavioral performance.
Acclimation to daily thermal variability drives the metabolic performance curve
(2013) Bozinovic, Francisco; Catalan, Tamara P.; Estay, Sergio A.; Sabat, Pablo
Background: Among the predictions of the effect of future climate change, the impact of thermal conditions at local levels on the physiological performance of individuals and their acclimation capacities is key to understanding animals' responses to global warming.
Age-Dependent Behavioral and Synaptic Dysfunction Impairment Are Improved with Long-Term Andrographolide Administration in Long-Lived Female Degus (Octodon degus)
(2023) Oliva, Carolina A.; Rivera, Daniela S.; Torres, Angie K.; Lindsay, Carolina B.; Tapia-Rojas, Cheril; Bozinovic, Francisco; Inestrosa, Nibaldo C.
In Octodon degus, the aging process is not equivalent between sexes and worsens for females. To determine the beginning of detrimental features in females and the ways in which to improve them, we compared adult females (36 months old) and aged females (72 months old) treated with Andrographolide (ANDRO), the primary ingredient in Andrographis paniculata. Our behavioral data demonstrated that age does not affect recognition memory and preference for novel experiences, but ANDRO increases these at both ages. Sociability was also not affected by age; however, social recognition and long-term memory were lower in the aged females than adults but were restored with ANDRO. The synaptic physiology data from brain slices showed that adults have more basal synaptic efficiency than aged degus; however, ANDRO reduced basal activity in adults, while it increased long-term potentiation (LTP). Instead, ANDRO increased the basal synaptic activity and LTP in aged females. Age-dependent changes were also observed in synaptic proteins, where aged females have higher synaptotagmin (SYT) and lower postsynaptic density protein-95 (PSD95) levels than adults. ANDRO increased the N-methyl D-aspartate receptor subtype 2B (NR2B) at both ages and the PSD95 and Homer1 only in the aged. Thus, females exposed to long-term ANDRO administration show improved complex behaviors related to age-detrimental effects, modulating mechanisms of synaptic transmission, and proteins.
Andrographolide Reduces Neuroinflammation and Oxidative Stress in Aged Octodon degus
(SPRINGER, 2020) Lindsay, Carolina B.; Zolezzi, Juan M.; Rivera, Daniela S.; Cisternas, Pedro; Bozinovic, Francisco; Inestrosa, Nibaldo C.
Alzheimer's disease (AD) is a devastating neurodegenerative disorder in which superior brain functions, such as memory and cognition, are impaired. Currently, no effective treatment is available for AD. Although andrographolide (ANDRO), a compound extracted from the herb Andrographis paniculata, has shown interesting effects in models of several diseases, including AD, its effects on other molecular changes observed in AD, such as neuroinflammation and oxidative stress, have not yet been studied. To evaluate the impact of ANDRO-based intervention on the levels of amyloid-beta (A beta) and neuroinflammatory and oxidative stress markers in the brains of aged Octodon degus, a Chilean rodent, fifty-six-month-old O. degus were treated intraperitoneally with 2 or 4 mg/kg ANDRO. Vehicle-injected and 12-month-old O. degus were used as positive controls. Then, the protein levels of selected markers were assessed via immunohistochemistry and immunoblotting. ANDRO significantly reduced the total A beta burden as well as astrogliosis and interleukin-6 levels. Moreover, ANDRO significantly reduced the levels of 4-hydroxynonenal and N-tyrosine adducts, suggesting a relevant reduction in oxidative stress within aged O. degus brain. Considering that O. degus has been proposed as a potential "natural" model for sporadic AD due to the development of neuropathological markers that resemble this pathology, our results suggest that ANDRO should be further studied to establish its potential as a therapeutic drug for AD.
Basal metabolism is correlated with habitat productivity among populations of degus (Octodon degus)
(2009) Bozinovic, Francisco; Rojas, Jose M.; Broitman, Bernardo R.; Vasquez, Rodrigo A.
Several competing hypotheses attempt to explain how environmental conditions affect mass-independent basal metabolic rate (BMR) in mammals. One of the most inclusive is the hypothesis that associates BMR with food habits, including habitat productivity. The effects of food habits have been widely investigated at the interspecific level, and variation between individuals and populations has been largely ignored. Intraspecific analysis of physiological traits has the potential to compensate for many pitfalls associated with interspecific analyses and serve as a useful approach for evaluating hypotheses regarding metabolic adaptation. Here we tested the effects of climatic variables (mean annual rainfall=PP, mean annual temperature=TA), net primary productivity (NPP) and the de Martonne index (DMi) of aridity on mass-independent BMR among four populations of the caviomorph rodent Octodon degus along a geographic gradient in Chile. BMR was measured on animals maintained in a common garden acclimation set-up, thus kept under the same environment and diet quality for at least 6 months. Mass-independent BMR was significantly different among degu populations showing a large intraspecific spread in metabolic rates. A very large fraction of interpopulational variability in mass-independent BMR was explained by NPR PP and DMi. Our results were conclusive about the effects of habitat productivity on setting the level of mass-independent BMR at the intraspecific-interpopulational level. (C) 2009 Elsevier Inc. All rights reserved.
Body Composition and Energy Savings by Hibernation: Lessons from the South American Marsupial Dromiciops gliroides
(2022) Mejias, Carlos; Navedo, Juan G.; Sabat, Pablo; Franco, Lida M.; Bozinovic, Francisco; Nespolo, Roberto F.
Hibernation (i.e., seasonal or multiday torpor) has been described in mammals from five continents and represents an important adaptation for energy economy. However, direct quantifications of energy savings by hibernation are challenging because of the complexities of estimating energy expenditure in the field. Here, we applied quantitative magnetic resonance to determine body fat and body composition in hibernating Dromiciops gliroides (monito del monte). During an experimental period of 31 d in winter, fat was significantly reduced by 5.72 +/- 0.45 g, and lean mass was significantly reduced by 2.05 +/- 0.14 g. This fat and lean mass consumption is equivalent to a daily energy expenditure of hibernation (DEEH) of 8.89 +/- 0.6 kJ d(-1) , representing 13.4% of basal metabolic rate, with a proportional contribution of fat and lean mass consumption to DEEH of 81% and 18%, respectively. During the deep heterothermic bouts of monitos, body temperature remained 0.41 degrees C +/- 0.2 degrees C above ambient temperature, typical of hibernators. Animals shut down metabolism and passively cool down to a critical defended temperature of 5.0 degrees C +/- 0.1 degrees C, where they begin thermoregulation in torpor. Using temperature data loggers, we obtained an empirical estimation of minimum thermal conductance of 3.37 +/- 0.19 J g(-1) h(-1) degrees C-1, which is 107% of the expectation by allometric equations. With this, we parameterized body temperature/ambient temperature time series to calculate torpor parameters and metabolic rates in euthermia and torpor. Whereas the acute metabolic fall in each torpor episode is about 96%, the energy saved by hibernation is 88% (compared with the DEE of active animals), which coincides with values from the literature at similar body mass. Thus, estimating body composition provides a simple method to measure the energy saved by hibernation in mammals.
Climate change and population persistence in a hibernating marsupial
(2024) Nespolo, Roberto F.; Quintero-Galvis, Julian F.; Fonturbel, Francisco E.; Cubillos, Francisco A.; Vianna, Juliana; Moreno-Meynard, Paulo; Rezende, Enrico L.; Bozinovic, Francisco
Climate change has physiological consequences on organisms, ecosystems and human societies, surpassing the pace of organismal adaptation. Hibernating mammals are particularly vulnerable as winter survival is determined by short-term physiological changes triggered by temperature. In these animals, winter temperatures cannot surpass a certain threshold, above which hibernators arouse from torpor, increasing several fold their energy needs when food is unavailable. Here, we parameterized a numerical model predicting energy consumption in heterothermic species and modelled winter survival at different climate change scenarios. As a model species, we used the arboreal marsupial monito del monte (genus Dromiciops), which is recognized as one of the few South American hibernators. We modelled four climate change scenarios (from optimistic to pessimistic) based on IPCC projections, predicting that northern and coastal populations (Dromiciops bozinovici) will decline because the minimum number of cold days needed to survive the winter will not be attained. These populations are also the most affected by habitat fragmentation and changes in land use. Conversely, Andean and other highland populations, in cooler environments, are predicted to persist and thrive. Given the widespread presence of hibernating mammals around the world, models based on simple physiological parameters, such as this one, are becoming essential for predicting species responses to warming in the short term.
Differential Role of Sex and Age in the Synaptic Transmission of Degus (Octodon degus)
(2022) Oliva, Carolina A.; Rivera, Daniela S.; Mariqueo, Trinidad A.; Bozinovic, Francisco; Inestrosa, Nibaldo C.
Octodon degus are a diurnal long-lived social animal widely used to perform longitudinal studies and complex cognitive tasks to test for physiological conditions with similitude in human behavior. They show a complex social organization feasible to be studied under different conditions and ages. Several aspects in degus physiology demonstrated that these animals are susceptible to environmental conditions, such as stress, fear, feeding quality, and isolation. However, the relevance of these factors in life of this animal depends on sex and age. Despite its significance, there are few studies with the intent to characterize neurological parameters that include these two parameters. To determine the basal neurophysiological status, we analyzed basic electrophysiological parameters generated during basal activity or synaptic plasticity in the brain slices of young and aged female and male degus. We studied the hippocampal circuit of animals kept in social ambient in captivity under controlled conditions. The study of basal synaptic activity in young animals (12-24 months old) was similar between sexes, but female degus showed more efficient synaptic transmission than male degus. We found the opposite in aged animals (60-84 months old), where male degus had a more efficient basal transmission and facilitation index than female degus. Furthermore, female and male degus develop significant but not different long-term synaptic plasticity (LTP). However, aged female degus need to recruit twice as many axons to evoke the same postsynaptic activity as male degus and four times more when compared to young female degus. These data suggest that, unlike male degus, the neural status of aged female degus change, showing less number or functional axons available at advanced ages. Our data represent the first approach to incorporate the effect of sex along with age progression in basal neural status.
Distribution of aquaporins in the nasal passage of Octodon degus, a South-American desert rodent and its implications for water conservation
(2008) Gallardo, Pedro; Herrera, Sofia; Saffer, Karin; Bozinovic, Francisco
Rodents from arid and semiarid environments live under conditions where the spatial and temporal availability of water is limited. Octodon degus is a South-American desert-dwelling rodent inhabiting arid and semiarid habitats of central and northern Chile. Its survival depends on morphological, physiological and behavioral adaptations that allow water conservation. This rodent has a high urine concentrating ability, high capacity of fecal dehydration and low evaporative water loss, related to the ability of the nasal passages to condense water from the exhaled air; this water must be absorbed in order to avoid its accumulation in the nasal passages and potential loss through the nostrils. We hypothesize that aquaporins (AQPs) might be present in the nasal mucosa; therefore, we studied the distribution of AQP-1, AQP-2, AQP-3 and AQP-4 through immunocytochemistry. Intense AQP-1 labeling was observed throughout the subepithelial vascular network; no AQP-1 immunoreactivity was detected in olfactory and non-olfactory epithelial cells. No signal was detected for AQP-2 and 4. AQP-3 distribution was restricted to the surface non-olfactory epithelial cells lining the turbinates in narrow passages and blind spaces. Therefore, AQP-1 and AQP-3 coincided at the level of the turbinates, although in different cell types which suggest a pathway for water removal from the nasal surface first through AQP-3 in non-olfactory epithelial cells and then into the capillary lumen through AQP-1.
Do changes in dietary chemistry during ontogeny affect digestive performance in adults of the herbivorous rodent Octodon degus?
(2008) Sabat, Pablo; Bozinovic, Francisco
We characterize the flexibility in digestive performance in degus (Octodon degus) an herbivorous rodent. We tested the hypothesis that dietary and physiological-digestive flexibility are correlated. Degus were fed with artificial diets of different chemical composition from weaning to adulthood and their digestive performance was measured through records of apparent digestibility. The starch content of the acclimation diet was not correlated with protein digestibility nor was it correlated with starch digestibility. In addition, digestive tract morphology was not affected by dietary treatments. Hence, an absence of morphological and physiological flexibility related to digestive traits was observed in degus. The lower flexibility in digestive performance given by our dietary experimental treatments of degus, may be an evolutionary constraint related to their specialized herbivorous food habits. (C) 2007 Elsevier Inc. All rights reserved.
Does the presence of livestock alter the trophic behaviour of sympatric populations of wild camelids Vicugna vicugna Molina 1782 and Lama guanicoe Muller 1976 (Artiodactyla: Camelidae)? Evidence from Central Andes
(2016) Tirado, Carlos; Cortes, A.; Carretero, M. A.; Bozinovic, Francisco
We described and compared the diets of two sympatric Andean camelids, during the humid season (austral summer) in a site of Northern Chile, in presence of domestic livestock. Results indicate that: 1) grasses and shrubs are the main component in the diet of both camelids, 2) shrubs were more consumed by V. vicugna; 3) V. vicugna and L. guanicoe used the same trophic resources but in different proportions; 4) in mountain environments, wetlands exploitation by wild camelids seems restricted by domestic cattle, which would cause the displacement of Vicunas and Guanacos to suboptimal habitat for feeding.
Does thermal physiology explain the ecological and evolutionary success of invasive species? Lessons from ladybird beetles
(2018) Boher, Francisca; Jaksic, Fabian M.; Martel, Sebastian I.; Orellana, Maria J.; Bozinovic, Francisco
Background: Several hypotheses have been proposed to explain invasive species success. Much of the research in this field has been conducted at the ecosystem or community level. Physiological traits are usually ignored, although they may play a role. As invasiveness has been correlated with species range expansion, it has been assumed - but scarcely tested - that species with greater physiological thermotolerances could be more invasive and colonize more habitats.
Effects of long-lasting social isolation and re-socialization on cognitive performance and brain activity: a longitudinal study in Octodon degus
(2020) Rivera, Daniela S.; Lindsay, Carolina B.; Oliva, Carolina A.; Francisco Codocedo, Juan; Bozinovic, Francisco; Inestrosa, Nibaldo C.
Social isolation is considered a stressful situation that results in increased physiological reactivity to novel stimuli, altered behaviour, and impaired brain function. Here, we investigated the effects of long-term social isolation on working memory, spatial learning/memory, hippocampal synaptic transmission, and synaptic proteins in the brain of adult female and male Octodon degus. The strong similarity between degus and humans in social, metabolic, biochemical, and cognitive aspects, makes it a unique animal model that can be highly applicable for further social, emotional, cognitive, and aging studies. These animals were socially isolated from post-natal and post-weaning until adulthood. We also evaluated if re-socialization would be able to compensate for reactive stress responses in chronically stressed animals. We showed that long-term social isolation impaired the HPA axis negative feedback loop, which can be related to cognitive deficits observed in chronically stressed animals. Notably, re-socialization restored it. In addition, we measured physiological aspects of synaptic transmission, where chronically stressed males showed more efficient transmission but deficient plasticity, as the reverse was true on females. Finally, we analysed synaptic and canonical Wnt signalling proteins in the hypothalamus, hippocampus, and prefrontal cortex, finding both sex-and brain structure-dependent modulation, including transient and permanent changes dependent on stress treatment.
Extreme elevational migration spurred cryptic speciation in giant hummingbirds
(2024) Williamson, Jessie L.; Gyllenhaal, Ethan F.; Bauernfeind, Selina M.; Bautista, Emil; Baumann, Matthew J.; Gadek, Chauncey R.; Marra, Peter P.; Ricote, Natalia; Valqui, Thomas; Bozinovic, Francisco; Singh, Nadia D.; Witt, Christopher C.
The ecoevolutionary drivers of species niche expansion or contraction are critical for biodiversity but challenging to infer. Niche expansion may be promoted by local adaptation or constrained by physiological performance trade-offs. For birds, evolutionary shifts in migratory behavior permit the broadening of the climatic niche by expansion into varied, seasonal environments. Broader niches can be short-lived if diversifying selection and geography promote speciation and niche subdivision across climatic gradients. To illuminate niche breadth dynamics, we can ask how "outlier" species defy constraints. Of the 363 hummingbird species, the giant hummingbird (Patagona gigas) has the broadest climatic niche by a large margin. To test the roles of migratory behavior, performance trade-offs, and genetic structure in maintaining its exceptional niche breadth, we studied its movements, respiratory traits, and population genomics. Satellite and light-level geolocator tracks revealed an >8,300-km loop migration over the Central Andean Plateau. This migration included a 3-wk, similar to 4,100-m ascent punctuated by upward bursts and pauses, resembling the acclimatization routines of human mountain climbers, and accompanied by surging blood-hemoglobin concentrations. Extreme migration was accompanied by deep genomic divergence from high-elevation resident populations, with decisive postzygotic barriers to gene flow. The two forms occur side-by-side but differ almost imperceptibly in size, plumage, and respiratory traits. The high-elevation resident taxon is the world's largest hummingbird, a previously undiscovered species that we describe and name here. The giant hummingbirds demonstrate evolutionary limits on niche breadth: when the ancestral niche expanded due to evolution (or loss) of an extreme migratory behavior, speciation followed.
Flight initiation distance is differentially sensitive to the costs of staying and leaving food patches in a small-mammal prey
(CANADIAN SCIENCE PUBLISHING, 2009) Lagos, Patricio A.; Meier, Andrea; Ortiz Tolhuysen, Liliana; Castro, Rodrigo A.; Bozinovic, Francisco; Ebensperger, Luis A.
Escape theory predicts that a prey should flee from an approaching predator at a point in which the cost of staying equals the cost of escape. We manipulated the cost of fleeing upon approaching human predators by providing the small mammal Octodon degus (Molina, 1782) with varying amounts of supplementary food likely to disappear while the animals are not in the food patch (e.g., hidden in their burrows). Simultaneously, we manipulated the risk of remaining in the patch by providing supplementary food at varying distances from the nearest burrow. Degus fled at a shorter distance to approaching predators when foraging in patches closer to the nearest burrow and supplied with relatively high abundance of food, but only when these rodents were foraging socially. Also, degus fled at a greater distance to approaching predators when foraging in patches far from the nearest burrow. Thus, functions linked to the loss of feeding opportunities and the risk of predation interact to influence flight initiation distance after a simulated attack. This study represented one of the few demonstrations of an interactive effect between cost and risks on antipredator behavior in a small, social prey mammal.
Genetic variation for plasticity in physiological and life-history traits among populations of an invasive species, the terrestrial isopod Porcellio laevis
(2008) Lardies, Marco A.; Bozinovic, Francisco
Background: Evolutionary interpretations of life-history as well as physiological patterns require distinction between genotypic variations and environmentally induced phenotypic variation.
Gut size variation among Bufo spinulosus populations along an altitudinal (and dietary) gradient
(2009) Naya, Daniel E.; Veloso, Claudio; Bozinovic, Francisco
To date, digestive flexibility has been studied in dozens of vertebrate species. However, practically all of these works has ignored the importance of intraspecific physiological variability across populations inhabiting different habitats. Here, we compare the digestive tract gross morphology of three populations of the Andean toad (Bufo spinulosus), inhabiting along an altitudinal gradient and feeding on different food items. Results support a core prediction of digestive theory, i.e., intestinal length increases in parallel with the content of indigestible material in the natural diet. The present study suggest how variation in the abiotic environment associated with altitude (e.g., temperature, water availability, soil quality) can change biotic conditions (e.g., vegetation cover, prey availability), affect feeding behavior of individuals (e.g., width and composition of trophic niche), and, ultimately, individuals' digestive features (e.g., gut morphology).
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.
Immunological vulnerability and adjustments to environmental thermal variability
(2013) Bozinovic, Francisco; Catalan, Tamara P.; Kalergis, Alexis M.
Ecological physiologists recognize the potential impacts of temperature on physiological traits, however less attention has been paid to changes in thermal variation on a scale that pertains directly to living organisms. Also, few studies have examined the effects of temperature variation or other climatic drivers on host-pathogen interactions. We evaluated the effect of acclimation to ambient temperature variability (0, 4 and 8 degrees C daily variability) on the immune performance in the insect Tenebrio molitor (Coleoptera). We observed that antibacterial activity differed significantly between treatments. In addition, variances of antibacterial activity were larger under the more variable thermal conditions. Similarly to antibacterial responses, tyrosinase phenoloxidase activity was higher in animals living in the most variable thermal condition. We hypothesized that a stress-associated mechanism may affect negatively the constitutive immune activity in T molitor It is well known that acute stress can cause in insects a transient impairment in the resistance to bacterial infection. This increase in susceptibility to diseases is mediated, at least in part, by the release of neuro-hormones in response to stress.

Browsing by Author "Bozinovic, Francisco"

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