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Veronica Measroch - One of the best experts on this subject based on the ideXlab platform.
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growth and reproduction in the females of two species of gerbil Tatera brantsi a smith and Tatera afra gray
Journal of Zoology, 2010Co-Authors: Veronica MeasrochAbstract:Summary. 1 The Tatera brantsi material consisted of 360 females collected between January and December 1946 from the Reef area around Johannesburg. Transvaal, and also of seventeen females which were kept in captivity for eleven months. The oestrus cycle of the laboratory females was studied by means of daily vaginal smears. The cycle lasted from four to six days from one pro-oestrus to the next. The average length of gestation was twenty-two and a half days and of lactation twenty-two to twenty-four days. It was apparent that in captivity the gerbils tended to go into anoestrus and only aporadic pregnancies occurred. The clean body-weight of females from the field ranged from 12 to 106 gm. with a mean of 60.05. The estimated weight at birth was 5.5 grams the lightest adult female weighed 37 gm. and the lightest pregnant female 52 gm. Breeding occurred all the year round but was reduced to a minimum in October, November and December. The age at puberty is discussed. It is estimated that a single female produces five to six litters in one year. The mean number of corpora lutea was 2.94 and of embryos 2.64. The different stages of the reproductive cycle are described. 2 The T. afra material consisted of 422 females obtained between January and December 1946, in the region of the South-west Cape. The females ranged from 15 to 90 gm in weight with a mean of 52.2 gm. The estimated weight at birth was 4.5 gm., the lightest adult female weighed 36 gm. and the lightest pregnant female 43 gm. The breeding season lasted eight months from the beginning of August until the end of March. The age at puberty is discussed. It was estimated that one female could produce six to seven litters in one season. The mean number of corpora lutea was 4.06 and of embryos 3.98. The relationship of the number of ova ovulated to the season, the body-weight and to intra-uterine mortality is discussed. 3 The main features of reproduction and breeding in T. afra and T. brantsi are compared and contrasted with those of some other small African mammals and British rodents.
P P De Moor - One of the best experts on this subject based on the ideXlab platform.
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seasonal variation in local distribution age classes and population density of the gerbil Tatera brantsi on the south african highveld
Journal of Zoology, 2009Co-Authors: P P De MoorAbstract:A grid containing 280 equally spaced trapping stations was laid out to investigate the population dynamics of the rodent Tatera brantsi (A. Smith) and its possible relationship to arthropod-borne viruses on the South African highveld. Estimates of the density and age distribution of the population indicated that breeding was minimal during the dry season (July to November) and reached a peak at the end of the rains in April and May. The range of activity was found to be significantly greater for males than for females. The nature of the dispersion of the animals in the grid area changed from highly aggregated at low population densities to random at high densities. The aggregation appeared to be correlated with the distribution of the sedge Cyperus esculentus, but it seemed likely that this correlation was spurious, and was due to an underlying disturbance of soil ecology caused by ploughing, which favoured clumping of both the rodents and the sedge in the same areas. There was no evidence that Tatera brantsi was involved in arbovirus transmission cycles.
K P Bland - One of the best experts on this subject based on the ideXlab platform.
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reproduction in the female indian gerbil Tatera indica
Journal of Zoology, 2009Co-Authors: K P BlandAbstract:The Indian gerbil, Tatera indica (Hardwicke) has been successfully maintained under laboratory conditions for 18 months, during which time over 250 vaginal cycles were recorded and 30 litters were born. Under laboratory conditions this animal had four-to-five-day oestrous cycles and sterile mating induced a ten-day pseudopregnancy. Anoestrus was not infrequent and was characterized by the absence of corpora lutea and large follicles from the ovaries and the atrophy of the uterus. The mean length of pregnancy was 22.3 days (range 18–30 days) and the litter size varied from two to seven young (mean 4.76 young). Mating at the post-partum oestrus resulted in delayed implantation if a litter of three or more young was being suckled. Under these circumstances pregnancy lasted 36 days (range 34–40 days). Implantation was interstitial and mesometrial. The chorioallantoic placenta was discoidal, labyrinthine and haemochorial probably becoming haemoendothelial just before term. Daily injection of ovine prolactin inhibited the occurrence of oestrus and caused enlargement of the corpora lutea in three of five animals. It is suggested that prolactin might be the luteotrophic hormone in this species.
Ernesto Capanna - One of the best experts on this subject based on the ideXlab platform.
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morphology and chromosomes of Tatera lataste 1882 rodentia muridae gerbillinae in west africa
Tropical Zoology, 2001Co-Authors: Paolo Colangelo, M V Civitelli, Ernesto CapannaAbstract:In a sample of the genus Tatera Lataste 1882 from West Africa (Benin and Burkina Faso), we analyzed the cranial and dental morphology and the karyotype (G, R, C and NOR banding). The cranial morphology confirms the attribution of this sample to Tatera kempi Wroughton 1906. An analysis of the dental morphology was also performed but it seems not to offer diagnostic traits. The karyotype described in the present work for T. kempi is comparable with that described for T. hopkinsoni Thomas 1911, supporting the synonymy of these two taxa. In contrast, the karyological results clearly discriminate kempi from both guineae and nigrita, the latter currently considered a synonym. In the karyotype of T. kempi, we found a polymorphism of a small chromosome, which occurs in the three situations: metacentric/metacentric, metacentric/acrocentric and acrocentric/ acrocentric. A similar polymorphism was described for hopkinsoni. The banding shows that the variation of the morphology of the X chromosome in Tatera is related to a pericentric inversion. KEY WORDS: Tatera, rodents, chromosomes, taxonomy, West Africa, evolution.
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I cromosomi dei Roditori del Benin (Africa Occidentale): 1. Cricetidi
Rendiconti Lincei, 1994Co-Authors: Jean T. Claude Codjia, Christophe Chrysostome, Maria Vittoria Civitelli, Ernesto CapannaAbstract:The chromosomes of the rodents of the Republic of Benin (West Africa): 1. Cricetidae. The karyotype has been studied in 2 species of Cricetomyinae, i.e. Cricetomys gambianus and Cricetomys emini, and one specie of Cricetinae, i.e. Tatern kempi , from forest and cultivated areas of the Republic of Benin. Chromosomes were obtained both by the standard bone marrow method and from cell cultures. Both Cricetomys species show a similar diploid number, that is C. gambianus 2n 82, and C emini 2n 80, minor structural diversities were evidenced by the comparison between karyotypes involving nucleolar chromosomes and the morphology of heterochromosomes. Tatera kempi shows a 48 chromosome karyotype: the problems of taxonomy and chromosome variability within the genus Tatera have been also discussed. È stato studiato il cariotipo di due Cricetomini, Cricetomys gambianus e Crycetomys emini , e di un Cricetino, Tatera kempi , provenienti da biotopi forestali e da coltivi del Benin meridionale (Africa occidentale). I cromosomi sono stati ottenuti attraverso la comune tecnica da midollo rosso delle ossa da cellule cultivate in vitro. Le due specie di Cricetomys mostrano un simile numero diploide: 2n 82 in C gambianus e 2n 80 in C. emini ; tuttavia peculiarità strutturali emergono dal confronto tra i cariotipi delle due specie, riguardanti la morfologia degli eterocromosomi e il numéro e la localizzazione delle aree nucleolo organizzatrici. Il cariotipo di Tatera kempi è composto da 48 cromosomi. È stato anche discusso il problema délia tassonomia e délia variabilité cariotipica del génère Tatera .
Surendra P. Goyal - One of the best experts on this subject based on the ideXlab platform.
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A simple mechanical device for recording the diel activity pattern of small burrowing mammals in their natural habitats
Journal of Zoology, 2009Co-Authors: Surendra P. GoyalAbstract:A mechanical device for monitoring the diel activity pattern of small burrowing mammals under natural conditions is described. The device has been used to estimate the time spent by the Indian gerbil, Tatera indica indica Hardwicke in foraging above ground and in an underground nest which is a part of the device. Activity patterns recorded with this device have confirmed observations that Tatera i, indica is nocturnal. The average time spent by this rodent outside the nest during an eight day study period was 318 min/24h. These rodents are generally active between 1900–0300 hrs, apparently with two peaks of activity, one between 2100–2200 hrs and the other between 0100–0200 hrs.
