Browsing by Author "Sassi, Paola L."

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    Plasticity in food assimilation, retention time and coprophagy allow herbivorous cavies (Microcavia australis) to cope with low food quality in the Monte desert
    (2010) Sassi, Paola L.; Caviedes-Vidal, Enrique; Anton, Rosa; Bozinovic, Francisco
    Energy balance depends on the efficiency with which organisms make use of their trophic resources and has, direct impact on their fitness. There are environmental variations that affect the availability as well as the quality of such resources; energy extraction also depends on the design of the digestive tract. It is expected that features associated with food utilization will be subjected to selective pressures and show some adjustment to the variability of the environment. Since energetic constraints challenge animals to display digestive compensatory mechanisms, the objective of this study is to determine the physiological and behavioral responses to spatial and seasonal heterogeneity in food quality. We investigated digestive strategies (digestive efficiency and coprophagy) in cavies inhabiting two different populations, and hence naturally experiencing different levels of diet quality. Cavies under experimentally different quality diets showed changes in dry matter digestibility and intake, digesta retention time and coprophagy. Our results partially support the expectations from theory and also reveal interpopulation differences in the ability to cope with changes in food quality, and may explain the capability of Microcavia australis to colonize extreme habitats. (C) 2009 Elsevier Inc. All rights reserved.
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    Spatial and seasonal plasticity in digestive morphology of cavies (Microcavia australis) inhabiting habitats with different plant qualities
    (2007) Sassi, Paola L.; Borghi, Carlos E.; Bozinovic, Francisco
    Ecological physiology examines how animals cope with changing environmental demands. In low-productivity desert habitats, small mammals should consume low-quality, high-fiber food as a consequence of necessity rather than by choice. Diet quality of populations can differ at both spatial and temporal scales. Nevertheless, spatial and temporal variation in the digestive system has not been extensively studied in the field. We captured individuals from 4 populations of Microcavia australis and measured their digestive morphological traits. Fieldwork was carried out in 4 localities belonging to and and semiarid regions, in dry and wet seasons. We also estimated diet quality for each population and season. We found significant effects of sex, season, and site on the size of digestive organs. The concentration of fiber and nitrogen in the plants consumed differed between populations and varied seasonally: dietary fiber was higher in the dry season and nitrogen concentration was higher in the wet season. As predicted by theory, the cecum, the organ most closely related to cellulose fermentation, was significantly larger in animals facing the lowest quality diet. The other organs also were affected by reproductive state and water requirements. Intraspecific variation in the digestive morphology of M. australis probably helps this species cope with remarkable seasonal and geographical variability.