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The ability of organisms to perform at different temperatures could be described by a continuous nonlinear reaction norm (i.e., thermal performance curve, TPC), in which the phenotypic trait value varies as a function of temperature. Almost any shift in the parameters of this performance curve could highlight the direct effect of temperature on organism fitness, providing a powerful framework for testing thermal adaptation hypotheses. Inter-and intraspecific differences in this performance curve are also reflected in thermal tolerances limits (e.g., critical and lethal limits), influencing the biogeographic patterns of species’ distribution. Within this context, here we investigated the intraspecific variation in thermal sensitivities and thermal tolerances in three populations of the invasive snail Cornu aspersum across a geographical gradient, characterized by different climatic conditions. Thus, we examined population differentiation in the TPCs, thermal-coma recovery times, expression of heat-shock proteins and standard metabolic rate (i.e., energetic costs of physiological differentiation). We tested two competing hypotheses regarding thermal adaptation (the “hotter is better” and the generalist-specialist trade-offs). Our results show that the differences in thermal sensitivity among populations of C. aspersum follow a latitudinal pattern, which is likely the result of a combination of thermodynamic constraints (“hotter is better”) and thermal adaptations to their local environments (generalist-specialist trade-offs). This finding is also consistent with some thermal tolerance indices such as the Heat-Shock Protein Response and the recovery time from chill-coma. However, mixed responses in the evaluated traits suggest that thermal adaptation in this species is not complete, as we were not able to detect any differences in neither energetic costs of physiological differentiation among populations, nor in the heat-coma recovery. 相似文献
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Leonardo D. Bacigalupe Diego M. Bustamante Francisco Bozinovic Roberto F. Nespolo 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(2):293-299
A major goal of evolutionary physiology is to understand the intrinsic and the extrinsic factors that impose limitations on
an animal’s energy budget. Although natural selection acts upon organismal traits such as performance (e.g., burst, sustained
metabolic rates), from a mechanistic perspective, organismal performance results from the integrated functioning of different
levels of biological organization. Hence, a better understanding of whole-animal performance must necessarily incorporate
an explicit analysis of the integration between those different levels. Although this topic has been under intense scrutiny,
overall there have been very few consistent patterns. Here, we explore the phenotypic integration between organ masses and
the overall energy budget under routine capacities by statistically decomposing the covariance matrix (using path analysis
and canonical correlation analysis) between organ masses and thermoregulatory burst and sustained metabolisms in cold acclimated
individuals of Phyllotis darwini. Our results suggest that (a) central organs associated with the processing of food (cecum and liver), residuals (kidneys)
and pumping of O2 (heart) are tightly integrated to sustained expenditure and between themselves; (b) with the exception of the heart, central
energy supplying organs are weakly related to burst expenditures; (c) sustained and burst metabolisms refer to complete different
strategies and (d) basal metabolic rate is not related to any of the physiological or morphological traits considered in this
study. Overall, our results support the hypothesis of an economic phenotype: animals maintain their excess capacities to face
those critical extreme events, but their physiology and internal morphology are tightly integrated to function under routine
needs. 相似文献
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Artacho P Soto-Gamboa M Verdugo C Nespolo RF 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2007,147(4):1060-1066
Living organisms are continuously faced with several forms of environmental perturbation, one of the most important being human activity. In this scenario, the role of physiological studies on wildlife has proved to be important given that in vivo physiological variables reflect a great deal how sensitive animals are to acute environmental changes. We studied the haematological parameters in black-necked swans (Cygnus melanocoryphus) at the Ramsar site at the Carlos Anwandter Sanctuary, which were experiencing a drastic population decrease. Through seven months, body mass (body mass corrected by total length) was reduced 30%, which was followed by significant reductions of haemoglobin concentration, haematocrit and red blood cell count. Mean cell volume and mean cell haemoglobin concentration did not change with time, whereas there was a significant increase of the white blood cells and heterophile / lymphocyte ratio. Our results, together with the published evidence, suggests that the proximal factors associated with the mass mortality and emigration of the black - necked swan population at the "Carlos Anwandter Sanctuary" was a drastic nutritional deficiency, and the potentially toxic effects of iron pollution in the waters of the Ramsar site. 相似文献
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Luis E. Castañeda Christian C. Figueroa Leonardo D. Bacigalupe Roberto F. Nespolo 《Journal of insect physiology》2010,56(12):1920-1924
Wing dimorphism has been proposed as a strategy to face trade-offs between flight capability and fecundity. In aphids, individuals with functional wings have slower development and lower fecundity compared with wingless individuals. However, differential maintenance costs between winged and wingless aphids have not been deeply investigated. In the current study, we studied the combined effect of wing dimorphism with the effects of aphid genotypes and of wheat hosts having different levels of chemical defences (hydroxamic acids, Hx) on adult body mass and standard metabolic rates (SMR) of winged and wingless morphs of the grain aphid, Sitobion avenae. We found that wingless aphids had higher body mass than winged aphids and that body mass also increased towards host with high Hx levels. Furthermore, winged aphids showed a plastic SMR in terms of Hx levels, whereas wingless aphids displayed a rigid reaction norm (significant interaction between morph condition and wheat host). These findings suggest that winged aphids have reduced adult size compared to wingless aphids, likely due to costs associated to the development of flight structure in early-life stages. These costs contrast with the absence of detectable metabolic costs related to fuelling and maintenance of the flight apparatus in adults. 相似文献
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Rodrigo Scheihing Leyla Cardenas Roberto F. Nespolo Paola Krall Katherina Walz Shiro Kohshima Pedro Labarca 《Hydrobiologia》2010,637(1):45-52
In small metazoan invertebrates classical taxonomic analyses can be ambiguous due to the limited number of morphological characters
available. This difficulty can yield incorrect estimates of species richness or taxa distribution. The Boeckella genus has been described as the dominant taxon of zooplankton assemblages in the Andean biogeographical region. In this genus,
taxonomic classification and delimitation of boundaries between species has long been problematic and controversial. Among
South American centropagids Boeckella gracilipes has been regarded as one of the most broadly distributed species, its presence having been reported from Ecuador to Tierra
del Fuego. However, in the high Andean plateau some centropagid populations identified as Boeckella gracilipes have also been considered as B. gracilipes titicacae or even identified as a different species, namely Boeckella titicacae. In an attempt to resolve the taxonomic status of the Centropagidae family from the high Andean plateau, we combined traditional
and multivariate morphological analyses (integral approach) with the molecular phylogenetic approach. The results obtained
allow us to conclude that centropagids collected from the high Andean plateau actually represent a different species, B. titicacae, not B. gracilipes. The phylogenetic reconstruction of the South American Centropagidae family indicated that B. gracilipes represents a sister taxon to B. titicacae. The present study stresses the usefulness of integrating alfa-taxonomy with morphometric and molecular approaches in order
to resolve species boundaries, to determine geographical distributions and to investigate evolutionary processes. 相似文献
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Castaneda LE Sabat P Gonzalez SP Nespolo RF 《Physiological and biochemical zoology : PBZ》2006,79(5):919-926
Anuran metamorphosis is one of the most spectacular processes in nature. Metamorphosis entails morphological transformations and extensive changes in feeding habits, such as transforming from an herbivore to a carnivore. This phenomenon is especially sensitive to environmental cues. We studied the phenotypic plasticity of intestinal morphology and enzyme activity in tadpoles of the Chilean giant frog Caudiverbera caudiverbera. We tested the effects of diet and temperature using a factorial design, which included a control of nontreated individuals. There was no significant effect of diet treatment (i.e., low- vs. high-quality diet) on any of the measured variables, including external morphology. We found significant effects of temperature on morphological traits. Temperature treatment also had significant effects on aminopeptidase-N and maltase activity. Both enzymes exhibited complex interactions with temperature along the intestine. Gut size varied significantly among temperatures, with intestines from warm-treated individuals smaller than the intestines from control and cold-treated tadpoles. Our findings suggest that phenotypic plasticity of intestinal morphology and physiology exists in larvae of this species, at least in response to temperature. However, we did not detect clear effects of diet or temperature on the timing of metamorphosis. 相似文献
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