Browsing by Author "Sabuni, C. A."

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Arenavirus infection correlates with lower survival of its natural rodent host in a long-term capture-mark-recapture study
(2018) Mariën, J.; Sluydts, V.; Borremans, B.; Gryseels, S.; Broecke, B. V.; Sabuni, C. A.; Katakweba, A. A. S.; Mulungu, L. S.; Günther, S.; de Bellocq, J. G.; Massawe, A. W.; Leirs, H
Background: Parasite evolution is hypothesized to select for levels of parasite virulence that maximise transmission success. When host population densities fluctuate, low levels of virulence with limited impact on the host are expected, as this should increase the likelihood of surviving periods of low host density. We examined the effects of Morogoro arenavirus on the survival and recapture probability of multimammate mice (Mastomys natalensis) using a seven-year capture-mark-recapture time series. Mastomys natalensis is the natural host of Morogoro virus and is known for its strong seasonal density fluctuations. Results: Antibody presence was negatively correlated with survival probability (effect size: 5–8% per month depending on season) but positively with recapture probability (effect size: 8%). Conclusions: The small negative correlation between host survival probability and antibody presence suggests that either the virus has a negative effect on host condition, or that hosts with lower survival probability are more likely to obtain Morogoro virus infection, for example due to particular behavioural or immunological traits. The latter hypothesis is supported by the positive correlation between antibody status and recapture probability which suggests that risky behaviour might increase the probability of becoming infected.
Genetic structure and diversity of the black and rufous sengi in Tanzanian coastal forests
(Journal of Zoology, 2016) Sabuni, C. A.; Van Houtte, N.; Gryseels, S.; Maganga, S. L. S.; Makundi, Rhodes H.; Leirs, H.; Goüy de Bellocq, J.
The black and rufous sengi Rhynchocyon petersi is restricted to the Eastern ArcMountains and coastal forests of East Africa and considered vulnerable because ofhabitat fragmentation and degradation. Coastal forests are believed to have beenisolated from each other for thousands of years due to climatic changes. SinceR. petersi is described as strongly dependent on its forest habitat, we hypothesizedthat R. petersi from different forests would show genetic divergence. We investi-gated the genetic structure and diversity of this species in four coastal forests inTanzania using eight microsatellites and cytochrome b sequences. In total, 45 indi-viduals were captured after strenuous sampling efforts. For comparative purposeswe also sequenced the cytochrome b of 57 individuals from a sympatric rodent for-est species, Beamys hindei. The results indicate extant R. petersi have descendedfrom a single population of high effective size (Ne) with no forest-distinctive sig-nal. In contrast, B. hindei is more genetically structured: Although the most com-mon haplotype is found in the three closest forests, each forest harbours privatehaplotypes. Moreover, B. hindei Ne appeared 10 times smaller than R. petersi inZaraninge forest. While B. hindei results are consistent with the scenario of long-term isolation of coastal forests, the R. petersi are not. We suggest R. petersi mayless depend on forest habitat than previously suspected, consistent with anecdotalreports of sengis nesting in intervening agricultural habitat. From a conservationviewpoint, this sengi species therefore appears robust to the current spatial andtemporal scale of habitat fragmentation.
Happily together forever: temporal variation in spatial patterns and complete lack of territoriality in a promiscuous rodent
(The Society of Population Ecology and Springer Japan, 2014-01) Borremans, B.; Hughes, N. K.; Reijniers, J.; Sluydts, V.; Katakweba, A. A. S.; Mulungu, Loth S.; Sabuni, C. A.; Makundi, Rhodes H.; Leirs, H.
The availability of resources, their effect on population density and territoriality, and the ways in which these factors are interwoven with mating systems are important determinants of small mammal space use. It is often difﬁcult to study these patterns in an integrated way, however, especially because long-term data are needed but not readily available. In this paper, we investigate effects of population density, season and breeding status on home range patterns of the promiscuous rodent Mastomys natalensis using monthly capture-mark-recapture data collected over 17 years in a 3-ha grid. Home ranges were estimated using minimum convex polygons bounded by trap locations, and home range overlap and visitation rates were calculated as a measure of territoriality. As higher population densities coincide with increased resource availability, we predicted that home range sizes would correlate negatively with density. Furthermore, as M. natalensis is promiscuous and population densities are generally high, we predicted that territoriality would be low, and home range overlap would therefore be high. Contrary to expectations the home ranges of female adults increased with population density, although those of male adults and subadults followed the expected decrease. Home range overlap and visitation rates were generally high, and increased signiﬁcantly with population density. More importantly, they were never lower than those of simulated datasets consisting of randomly moved home ranges. These results therefore suggest that M. natalensis displays a complete lack of territoriality that is rarely seen in small mammals but still meets predictions based on knowledge of density and mating system.
Short communication - effects of azadirachta indica (neem) extract on livestock fleas in Morogoro district, Tanzania
(International Centre of Insect Physiology and Ecology, 2001) Kilonzo, B. S.; Ngomuo, A. J.; Sabuni, C. A.; Mgode, G. F.
Aqueous neem seed kernels extracts (NSKE) were used to treat flea-infested goats in Morogoro, Tanzania to determine their efficacy for flea control. Mean population densities of the insects were significantly lower in the treated goats compared to their untreated counterparts (P < 0.05). It was concluded that NSKE has potential in controlling livestock fleas, but further studies are needed to determine the active principals against fleas and their mode of action.
Spiny mice of the Zambezian bioregion – phylogeny, biogeography and ecological differentiation within the Acomys spinosissimus complex
(ELSEVIER, 2018-03-23) Katakweba, A. S.; Petruzela, J.; Sumbera, R.; Aghova, T.; Bryjova, A.; Sabuni, C. A.; Chitaukali, W. N.; Bryja, J.
Despite the high degree of biological diversity in the Zambezian region, little information is available regarding the evolutionary history of its biota, and this is especially true for the fauna and flora of non-forested habitats. Here we use the most comprehensive multi-locus genetic dataset available to (1) reconstruct the phylogeny of spiny mice of the Acomys spinosissimus complex and to describe the spatial distribution of its genetic diversity; (2) to assess the level of reproductive isolation between genetic clades; (3) to analyse differences in climatic niche between potential species; and (4) to model their current and past distribution. The complex comprises four main genetic clades that correspond to four nominal species living in the east of the Zambezian region. Their distribution is delimited by important geographical divides including the Eastern Arc Mountains, Lake Malawi and the Zambezi River. Two species considered Tanzanian endemics, A. ngurui and A. muzei, are now known to be more widespread than previously thought and they have their centres of genetic diversity just north of the Zambezi. The first split between the extant members of the A. spinosissimus complex is estimated at 3 Mya. Most intraspecific diversification events are thought to have occurred in the Pleistocene, suggesting that climatic oscillations played an important role in their diversification. The climatic niches of parapatric taxa differ significantly; hence, local adaptations have likely played an important role in reproductive isolation. Species distribution modelling predicts a dramatic reduction of occurrence probability across the area during the last interglacial period, facilitating allopatric diversification of fragmented populations. Our results strongly suggest the combined role of Pleistocene climatic change, biogeographical barriers and local adaptation in forming current taxa diversity in east African savannah-like habitats. While such processes have frequently been observed in forest-living organisms (theory of allopatric diversification in forest refugia), similar mechanisms were likely also working in open ecosystems ("savannah refugia").