Social Environment and Agonistic Interactions: Strategies in a Small Social Mammal

Which precocial rodent species is more suitable as the experimental model of microgravity influence on prenatal musculosketal development on international space station?

The International Space Station (ISS) has the possibility to perform experiments regarding rodent reproduction in microgravity. The musculoskeletal system at birth in precocial rodent species more resembles the human than that of altricial rodent species. For precocial rodent species with body weight ≤ 500 g (limit of ISS) determined were: adult body mass, newborn body mass, head-body length, tail length, existing variants (wild, domesticated, laboratory), single/group housing, dry food consumption/24 h, water intake/24 h, basal metabolic rate mlO2/g/h, environmental temperature, sand baths, urine output ml/24 h, fecal output g/24 h, size of fecal droplet, hair length, life span, length of oestrus cycle, duration of pregnancy, building nest, litter size, stage of musculoskeletal maturity at birth, and the duration of weaning. Characteristics were obtained by searching SCOPUS as well as the World Wide Web with key words for each of the species in English, Latin and, local language name. These characteristics were compared in order to find most appropriate species. Twelve precocial rodent species were identified. There is not enough data for Common yellow-toothed cavy, and Eastern spiny mouse. Inappropriate species were: Gundis, Dassie rat are a more demanding species for appropriate tending, litter size is small; Octodon degus requires sand baths as well as a nest during the first two weeks after delivery; muscle maturity of Spiny mouse at birth (myotubular stage), does not correspond to the human (late histochemical stage); Chinchilla requires separately housing, daily sand baths, has upper limit of weight. Possibility of keeping Southern mountain cavy as pet animal, short estrus, large litter size, absence of the need for nest and sand baths, makes this species the most promising candidates for experiments on ISS. If an experiment is planned with exposing gravid animals before term of the birth, then they might be kept together in the existing Rodent Habitat (USA). If an experiment with birth in microgravity is planned on ISS, the existing habitats do not provide conditions for such an experiment. It is necessary to develop habitats for separate keeping of pregnant animals to enable the following: 1. undisturbed delivery 2. prevent the possibility of hurting the newborns 3. ensure adequate post-partum maternal care and nursing.

First paleoparasitological study of micromammal coprolites from the holocene of the Somuncurá Plateau Protected Natural Area (Patagonia Argentina)

The Somuncurá Plateau is a Protected Natural Area located in the middle of the northern extra-Andean arid Patagonia. Inhabited by at least 20 small mammal species, is the place with the uppermost species richness in Patagonia. The aim of this study was to examine the parasite remains from micromammal coprolites collected in association with a bone sequence recovered at the east of the Somuncurá Plateau (site "Alero Las Lechuzas"). Coprolites came from the four temporal units previously defined: unit I (4790 ± 100 yrs. ¹⁴C B.P.), unit II, unit III (7840 ± 120 yrs. ¹⁴C B.P.) and unit IV. Each coprolite was processed, rehydrated, homogenized, processed by spontaneous sedimentation and examined using a light microscope. Coprolites and eggs were described, measured and photographed. Samples were positive for two nematode species: Helminthoxys caudatus Freitas, Lent & Almeida, 1937 (Oxyurida, Oxyuridae) and Trichuris spp. (Trichinellida: Trichuridae). This is the first paleoparasitological study developed for the Somuncurá Plateau Protected Area. Moreover, this is the first time that the genus Helminthoxys is reported from ancient times worldwide. Coprolites were attributed to the mountain cavy Microcavia australis (Rodentia, Caviidae).The presence of H. caudatus for the Middle Holocene of northern Patagonia contributes to the study of the history of the histricomorphs and pinworms relationships.

Characterization and selection of microhabitat of Microcavia australis (Rodentia: Caviidae): first data in a rocky habitat in the hyperarid Monte Desert of Argentina

A rocky habitat, in its broadest sense, may be described as any locality that contains boulders, rocks, scree, pebbles, outcrops, cliffs, or caves. In these habitats, mammals find shelter sites that they use as nesting sites or dens to raise their young in a stable microclimate that is relatively secure from predators. The aim of this study was to characterize and evaluate the microhabitat selection by the southern mountain cavy (

Renal intraspecific variation along an aridity gradient detected by new renal indices in a desert herbivorous rodent

Mammals that live in arid and semi-arid environments in South America present physiological mechanisms that enable them to conserve water. Body water is lost through the kidneys, lungs, skin, and intestines. Regarding renal adaptation for water conservation, several indices have been used to estimate the capacity of the kidneys to produce a maximum urine concentration. Most studies were conducted at an inter-specific level, with only few performed at the intraspecific level. In this work, we compare renal function and morphology among five populations of Southern mountain cavy, Microcavia australis, present along an aridity gradient. We hypothesized that individuals from drier zones would present morphological and functional renal modifications that imply a greater capability to conserve body water. These features were studied considering the classical indices (RMT, PMT, PMA, and RMA) and three new indices that consider area measurements; the latter showed to be more adequate to reflect intraspecific differences. Our results suggest that the morphological modifications of kidneys, that is, the greater areas of renal inner medulla, would be related to the aridity gradient where populations of Southern mountain cavy occur.