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1

Unvarying diet of a Neotropical desert marsupial inhabiting a variable environment: the case of Thylamys pallidior

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Albanese S., Dacar M. A., Ojeda R. A.
Acta Theriologica
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2012
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tom 57
|
nr 2
Studies on the diet and other aspects of the natural history of Neotropical marsupials have focused mainly on a few species from tropical and forest habitats. Research on desert marsupials, on the other hand, is almost absent outside Australia. The desert mouse opossum, Thylamys pallidior, is a small marsupial which inhabits the arid lands of Argentina, Chile, Bolivia, and Peru. In Argentina, it occurs in the Monte desert, a highly seasonal system with a heterogeneous landscape which affords a good opportunity to perform comparisons among different environmental situations. We analyzed fecal samples from 123 individuals and compared their diet among different seasons, habitat types, sexes, and ages. The diet of T. pallidior was composed of 68.7% of arthropods and 31.3% of plant material, mainly leaves (24.6%). We found no significant differences in the proportions of any main food category consumed for any of the factors analyzed. Consumption of both plant and animal material seems to be important in the diet of T. pallidior which manages to keep their proportions constant despite the strong variability and seasonality of the habitat. Contrary to most didelphid species, but similarly to most mammals of this area, leaves seem to represent an important source of food possibly because of their abundance and stability in the Monte desert. This represents the first study to focus on the diet of a Thylamys species inhabiting an arid environment.
2

Diet of wild boar (Sus scrofa) in a protected area of Argentina: the importance of baiting

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Ballari S. A., Cuevas M. F., Ojeda R. A., Navarro J. L.
Acta Theriologica
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2015
|
tom 60
|
nr 1
The wild boar is an invasive mammal in Argentina that generates habitat alteration, predation, and competition that threaten several native species due to its flexible and broad diet and its rooting behavior. We evaluated the diet of wild boar in El Palmar National Park (EPNP), assessing its composition, seasonality, and importance of baiting. Vegetable matter represented the major component of the diet, where corn was the most abundant food item, which is used as bait to hunt wild boars. Animal remains were also abundant and mostly consisted of birds. Wild boar diet exhibited marked seasonality that seems related to food availability, such as the occurrence of fruits in summer. Currently, the importance of bait in the diet could support and complement the diet of wild boar and improve their reproduction triggering the population growth. Also, the impacts on native biodiversity may be hidden due to the constant food subsidy of corn. We recommend the implementation of other control methods such as hunting with dogs or traps and the use of alternative baits, as odor baits, to avoid the supplemental feeding, or finally, if corn baiting is continuous, we suggest regulating their quantity and frequency. Further studies on wild boar diet and baiting methods should be conducted due to its multiple implications on wild boar populations and native ecosystems.
3

Seasonal variation in feeding habits and diet selection by wild boars in a semi-arid environment of Argentina

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Cuevas M. F., Ojeda R. A., Dacar M. A., Jaksic F. M.
Acta Theriologica
|
2013
|
tom 58
|
nr 1
The wild boar, Sus scrofa, was first introduced for hunting purposes in Argentina in 1906 and presently occupies a wide range of habitats. Understanding the food habits of invasive species is important for predicting the effects of animal food consumption on the environment and on human activities, such as farming. The wild boar is an omnivorous, opportunistic species whose diet is determined by the relative abundance of different types of foods. In general, the wild boar’s diet has been widely studied in the world, both as a native and invasive species, but little is known regarding food resource selection in the Monte Desert biome. Our study assessed the seasonal variation in the diet of wild boars, as well as the nutritional quality of consumed items. Further, we determined the diet selection of this species. Diet analyses were based on faecal samples collected over two seasons (wet and dry) in 1 year. Herbs were the most frequently consumed food item, with wild boars showing a selection for them in both seasons. The wild boar uses food resources according to seasonal availability (larger trophic niche breadth under higher plant diversity, as in the wet season). In turn, within each season, it selects items of high forage quality and high carbohydrate contents. In conclusion, this foraging strategy enables wild boar to maximize energy budget through food selection in order to survive in a semi-arid environment such as the Monte Desert.
4

A cytogenetic, molecular genetic and morphological study of Patagonian chinchilla mice Euneomys (Rodentia, Cricetidae) in the Southern Central Andes

64%
Ojeda A. A., Novillo A., Ovejero R. J. A., Cuello P. A., Lanzone C., Borisenko A. V., Braun J. K., Mares M. A., Ojeda R. A.
Acta Theriologica
|
2015
|
tom 60
|
nr 1
Euneomys is a genus of sigmodontine rodent endemic to South America, distributed along the Andes of Argentina and Chile and in adjoining Patagonian steppe. Here, we studied specimens of Euneomys from different localities in the Central Andes, Mendoza Province, Argentina. Karyotypic analyses confirm the presence of a new karyomorph of Euneomys chinchilloides, the form 2n = 34, FN = 62–64. This new karyomorph differs from the form E. chinchilloides with 2n = 36, FN = 64–66. The chromosome complement with 2n = 36 has an extra pair of small acro-telocentric chromosomes that is not present in individuals with 2n = 34. We also found small differences in molecular analyses with the mitochondrial COI gene. We recovered two monophyletic clades, one with specimens with 2n = 34 and the other one with specimens with 2n = 36, which are separated by a range of 0.7 to 1.2 % sequence divergence. Individuals from the two clades also show some morphological differences. Significant difference in the length of ear was found between the specimens with 2n = 34 and 36, and qualitative differences in the shape of the incisive foramen, the palate, and the palatine fossa were observed. The modification on fundamental and diploid number that we found between the two karyomorphs of E. chinchilloides can be the result of tandem chromosome fusion; such rearrangements are strongly negatively heterotic and lead to reproductive isolation between differentiated populations. Thus, the integrated cytogenetic, molecular, and morphologic analyses show concordant differentiation between the two karyomorph types of the uncommon E. chinchilloides from the Southern Central Andes of Argentina. The evidence presented here might reflect a recent and/or incipient allopatric speciation event. Further investigations are needed to elucidate the taxonomic and distributional status of species of Euneomys.
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