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Revista chilena de historia natural

Print version ISSN 0716-078X

Abstract

PARDINAS, ULYSES F. J.; MOREIRA, GERMAN J.; GARCIA-ESPONDA, CESAR M.  and  DE SANTIS, LUCIANO M.. Environmental deterioration and micromammals during the Holocene in northeastern Patagonian steppe (Argentina). Rev. chil. hist. nat. [online]. 2000, vol.73, n.1, pp.9-21. ISSN 0716-078X.  http://dx.doi.org/10.4067/S0716-078X2000000100002.

The qualitative and quantitative taxonomic composition of a micromammal sample from Lle cul (43º 20' S, 65º 35' W), in the lower valley of the Chubut River (Argentina), was analyzed. The age of the sample was 1,830 ± 70 yr BP. The association includes 6 species of sigmodontine rodents, two species of caviomorphs, two species of chiropterans, and two species of marmosine marsupials, including Calomys cf. C. laucha-C. musculinus (35.2%) and Eligmodontia sp. (33.4%) as the most abundant taxa. The analysis of frequency and corrosive marks on the skeletal remains indicates that the material was probably deposited during winter time by a strigiform bird, possibly Tyto alba, which explains the low level of bone corrosion. Comparison with a recent sample of pellets from Tyto alba from the same locality, in which Calomys cf. C. laucha-C. musculinus accounted for 95% of the total micromammals, shows a marked loss in today's species diversity. Comparison with modern samples of owl pellets from different Patagonian phytogeographic districts, together with paleoenvironmental evidence from the Late Holocene, indicate that human activities are probably the most important agent of the modification of the environment. Activities like overgrazing by sheep and expansion of agriculture may have aided both the dispersal as well as the increased present-day abundance of Calomys on account of another micromammals.

Keywords : rodents; Patagonia; Holocene; diversity; anthropic impact.

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