Rhabdomys
Encyclopedia
Rhabdomys is a small muroid rodent that is widespread and abundant in the southern Africa
n subregion (De Graaff, 1981; Willan & Meester, 1989; Pillay, 2000a, b, c; Skinner & Chimimba, 2005; Schradin & Pillay, 2005). Unlike most rodents, the Striped mouse exhibits a diurnal
, bimodal activity pattern, with activity concentrated around mornings and evenings, and reduced during the midday period (Perrin, 1981; Schumann et al., 2005). Its omnivorous diet, its ability to survive without water provided its food has a minimum water content of 15% (Willan, 1982), and its extreme plasticity in habitat preference are likely reasons for its wide (if discontinuous; Brooks, 1982) distribution throughout southern Africa (Rambau et al., 2003).
of 22–23 days, free-living females give birth to approximately five pups; captive females have slightly larger litters (e.g. 7.2 ±1.8; Pillay, 2000). Pups begin to consume solid food at ten days, leave the nest from twelve days, and weaning occurs at around 16 days. Sexual maturity
is reached at approximately five to six weeks (range 34 – 90 days; Brooks, 1982). Timing of sexual maturity, as well as dispersal age, depends on environmental factors (e.g. resource availability), social cues (e.g. the presence of older, reproductively active animals), as well as the animal’s developmental history (e.g. weight at weaning; sex-ratio of litter; Mason & Latham, 2004). Females have an inter-litter interval of approximately 23–30 days (Pillay, 2000).
. In arid
habitats (e.g. Namib; Krug, 2002; Kalahari; Nel, 1975; Nel & Rautenbach, 1975; Succulent karoo
; Schradin & Pillay, 2005a, b) Rhabdomys can be described as a territorial, group-living, solitary forager that displays biparental care (Schradin & Pillay, 2004). In mesic, grassland
habitats (e.g. Kwa-Zulu Natal Midlands; Wirminghaus & Perrin, 1993; Pretoria Highveld; Brooks, 1974; Zimbabwe
grassland; Choate, 1972) and semi-succulent thorny scrub (e.g. Eastern Cape
; Perrin, 1980a, b) animals are solitary, with females rearing their litters on their own, and both sexes maintain territories that overlap the territories of the opposite, but not the same, sex (Schradin & Pillay, 2005a). However, males from both mesic and xeric populations display parental care in captivity (Schradin & Pillay, 2005b), suggesting a plesiomorphic occurrence in the mesic populations, since the desert-living form represents the ancestral form (Rambau et al., 2003).
. Striped mice from the southwestern regions of southern Africa are slightly larger than animals from the more northern regions, and animals from the xeric western areas have a paler coat than do mice from the mesic, eastern regions (Pillay, 2000a, c). In addition, there appear to be population level differences in personality – an animal’s characteristic and consistent style of behaviour (Reif & Lesch, 2003) – and stress-sensitivity (suggested by Reuther, 2000), although these differences have yet to be investigated empirically.
forms of Rhabdomys (2n = 28 and 2n = 46) have been detected. Based on this finding and on the analysis of mitochondrial DNA
, as well as evidence of divergent behavioural repertoires among populations (e.g. courtship
behaviours; Pillay, 2000b; Pillay et al., 2006). Rambau et al. (2003) suggest that R. pumilio be reclassified as two species: R. pumilio (the social form that occurs in xeric habitats; 2n = 48) and R. dilectus (the solitary form, found in mesic areas, that comprises two subspecies R. d. dilectus, 2n = 46, and R. d. chakae, 2n = 48).
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n subregion (De Graaff, 1981; Willan & Meester, 1989; Pillay, 2000a, b, c; Skinner & Chimimba, 2005; Schradin & Pillay, 2005). Unlike most rodents, the Striped mouse exhibits a diurnal
Diurnal animal
Diurnality is a plant or animal behavior characterized by activity during the day and sleeping at night.-In animals:Animals that are not diurnal might be nocturnal or crepuscular . Many animal species are diurnal, including many mammals, insects, reptiles and birds...
, bimodal activity pattern, with activity concentrated around mornings and evenings, and reduced during the midday period (Perrin, 1981; Schumann et al., 2005). Its omnivorous diet, its ability to survive without water provided its food has a minimum water content of 15% (Willan, 1982), and its extreme plasticity in habitat preference are likely reasons for its wide (if discontinuous; Brooks, 1982) distribution throughout southern Africa (Rambau et al., 2003).
Breeding
Rhabdomys is a seasonal breeder and reproductively active from spring to autumn (Willan & Meester, 1989; Schradin & Pillay, 2003). After a gestation periodGestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
of 22–23 days, free-living females give birth to approximately five pups; captive females have slightly larger litters (e.g. 7.2 ±1.8; Pillay, 2000). Pups begin to consume solid food at ten days, leave the nest from twelve days, and weaning occurs at around 16 days. Sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
is reached at approximately five to six weeks (range 34 – 90 days; Brooks, 1982). Timing of sexual maturity, as well as dispersal age, depends on environmental factors (e.g. resource availability), social cues (e.g. the presence of older, reproductively active animals), as well as the animal’s developmental history (e.g. weight at weaning; sex-ratio of litter; Mason & Latham, 2004). Females have an inter-litter interval of approximately 23–30 days (Pillay, 2000).
Social structure
Rhabdomys has a flexible social organisation and mating system that appears to be shaped primarily by resource (particularly food and cover) availability and, secondarily, by population densityPopulation density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...
. In arid
Arid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
habitats (e.g. Namib; Krug, 2002; Kalahari; Nel, 1975; Nel & Rautenbach, 1975; Succulent karoo
Karoo
The Karoo is a semi-desert region of South Africa. It has two main sub-regions - the Great Karoo in the north and the Little Karoo in the south. The 'High' Karoo is one of the distinct physiographic provinces of the larger South African Platform division.-Great Karoo:The Great Karoo has an area of...
; Schradin & Pillay, 2005a, b) Rhabdomys can be described as a territorial, group-living, solitary forager that displays biparental care (Schradin & Pillay, 2004). In mesic, grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
habitats (e.g. Kwa-Zulu Natal Midlands; Wirminghaus & Perrin, 1993; Pretoria Highveld; Brooks, 1974; Zimbabwe
Zimbabwe
Zimbabwe is a landlocked country located in the southern part of the African continent, between the Zambezi and Limpopo rivers. It is bordered by South Africa to the south, Botswana to the southwest, Zambia and a tip of Namibia to the northwest and Mozambique to the east. Zimbabwe has three...
grassland; Choate, 1972) and semi-succulent thorny scrub (e.g. Eastern Cape
Eastern Cape
The Eastern Cape is a province of South Africa. Its capital is Bhisho, but its two largest cities are Port Elizabeth and East London. It was formed in 1994 out of the "independent" Xhosa homelands of Transkei and Ciskei, together with the eastern portion of the Cape Province...
; Perrin, 1980a, b) animals are solitary, with females rearing their litters on their own, and both sexes maintain territories that overlap the territories of the opposite, but not the same, sex (Schradin & Pillay, 2005a). However, males from both mesic and xeric populations display parental care in captivity (Schradin & Pillay, 2005b), suggesting a plesiomorphic occurrence in the mesic populations, since the desert-living form represents the ancestral form (Rambau et al., 2003).
Morphology
There is some regional variation in morphologyMorphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
. Striped mice from the southwestern regions of southern Africa are slightly larger than animals from the more northern regions, and animals from the xeric western areas have a paler coat than do mice from the mesic, eastern regions (Pillay, 2000a, c). In addition, there appear to be population level differences in personality – an animal’s characteristic and consistent style of behaviour (Reif & Lesch, 2003) – and stress-sensitivity (suggested by Reuther, 2000), although these differences have yet to be investigated empirically.
Karyotypic forms
Two karyotypicKaryotype
A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...
forms of Rhabdomys (2n = 28 and 2n = 46) have been detected. Based on this finding and on the analysis of mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
, as well as evidence of divergent behavioural repertoires among populations (e.g. courtship
Courtship
Courtship is the period in a couple's relationship which precedes their engagement and marriage, or establishment of an agreed relationship of a more enduring kind. In courtship, a couple get to know each other and decide if there will be an engagement or other such agreement...
behaviours; Pillay, 2000b; Pillay et al., 2006). Rambau et al. (2003) suggest that R. pumilio be reclassified as two species: R. pumilio (the social form that occurs in xeric habitats; 2n = 48) and R. dilectus (the solitary form, found in mesic areas, that comprises two subspecies R. d. dilectus, 2n = 46, and R. d. chakae, 2n = 48).