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Accueil du site → Doctorat → Allemagne → 2003 → Adaptations of the four-striped field mouse (Rhabdomys pumilio, Sparman 1784) to the Namib Desert

Universität Bonn (2003)

Adaptations of the four-striped field mouse (Rhabdomys pumilio, Sparman 1784) to the Namib Desert

Krug, Cornelia Bettina

Titre : Adaptations of the four-striped field mouse (Rhabdomys pumilio, Sparman 1784) to the Namib Desert

Auteur : Krug, Cornelia Bettina

Université de soutenance : Bonn, Univ., Diss., 2003

Résumé
Animals living in arid conditions need to adapt to a number of environmental factors, namely intense solar radiation, extreme temperatures, low humidity, (dry) winds, and temporal and spatial unpredictability of both water and nutrient availability, which shape life in deserts. Adaptations to survival under these arid conditions can be of morphological, physiological and behavioural nature (Costa 1995). In a 2-year study of Rhabdomys pumilio (Sparmann 1784), the fourstriped fieldmouse, it was examined how this species, which is widespread throughout Southern Africa and lives in wide variety of habitats, adapts to the arid conditions in the Namib Desert. Three different methodological approaches were used to collect information for this study : 1) Capture-Mark-Recapture, 2) direct observation of focal individuals and 3) dissection of the reproductive tract of female casualties. Data on diet, population structure, social structure, spatial structure and activity pattern of the species were obtained. Vegetation cover, which is important for the diurnal species, is mainly available under nara (Acanthosicyos horridus) plants, which form large hummocks. Rhabdomys are therefore forced to aggregate in these plants, which in turn influences population structure, social structure and spatial structure. Population densities are high, and fluctuate over the seasons. Animals live in extended family groups ; pairbonding and paternal care are observed. The homeranges of males and females overlap, no mutually exclusive homerange are found. The nara plant provided most of the food available to the species, Rhabdomys is found to be mainly herbivorous. Breeding was opportunistic, and tied to food availability ; females exhibit a postpartum oestrus under good conditions. Litter sizes are reduced compared to more mesic areas, and litters raised with a male present were larger. The species retains its diurnal activity pattern, with the main activity period in the morning and evening hours. The true opportunistic nature of R. pumilio and the choice of habitat enables the species to survive in a mesic micro-environment in the arid macro-environment of the Namib Desert.

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