The pattern of plague endemicity in Tanzania is characterized by continuous re-appearance of the disease in some locations,while in other neighbouring villages the disease has never or seldom been observed.To understa...The pattern of plague endemicity in Tanzania is characterized by continuous re-appearance of the disease in some locations,while in other neighbouring villages the disease has never or seldom been observed.To understand the reasons for this pattern,we studied small mammal and flea species composition,diversity and relative abundances in two plague-endemic and two plague-free locations.We asked(a)whether fleas more abundant in plague-endemic locations differ in their characteristic abundance and the degree of their host specificity from fleas more abundant in plague-free locations and(b)whether hosts most abundant in plague-endemic locations differ in the diversity of their flea assemblages from hosts most abundant in plague-free locations.We characterized(a)each host species by species richness and degree of taxonomic relatedness of its flea assemblages and(b)each flea species by its mean abundance and size,and degree of taxonomic relatedness of its host spectrum and compared their relative abundances between locations.No significant difference between plague-endemic and plague-free locations in either host density or any variable related to flea abundance or diversity was found.However,there was marginally significant effect of taxonomic distinctness of a flea assemblage harboured by a host on its probability to be more abundant in either plague-endemic or plague-free locations.Furthermore,hosts more abundant in plague-endemic locations tended to harbour closely-related fleas.Finally,while opportunistic and specialist fleas were equally distributed in both sets of locations,fleas exploiting distantly-related hosts were found mainly in plague-free locations during the rainy season.We suggest that the observed patterns might arise due to seasonal and spatial differences in local microclimatic conditions and landscape connectivity.展开更多
The lesser pouched rat,Beamys hindei,is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa.The ecology of this species and its current distribution in coastal f...The lesser pouched rat,Beamys hindei,is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa.The ecology of this species and its current distribution in coastal forests is not well known.Therefore,we conducted a study in selected coastal forests to assess the current distribution of the species and to investigate the population ecology in terms of abundance fluctuations and demographic patterns.Assessments of the species distribution were conducted in 5 forests through trapping with Sherman live traps.Data on ecology were obtained from monthly capture–mark–recapture studies conducted for 5 consecutive nights per month in two 1 ha grids set in Zaraninge Forest over a 2-year period.The results indicate the presence of B.hindei in 3 forests where it was not previously recorded.The population abundance estimates ranged from 1 to 40 animals per month,with high numbers recorded during rainy seasons.Reproduction patterns and sex ratios did not differ between months.Survival estimates were not influenced by season,and recruitment was low,with growth rate estimates of 1 animal per month.These estimates suggest a stable population of B.hindei in Zaraninge Forest.Further studies are recommended to establish the home range,diet and burrowing behavior of the species in coastal forests in East Africa.展开更多
Consistent among individual variation in behavior,or animal personality,is present in a wide variety of species.This behavioral variation is maintained by both genetic and environmental factors.Parental effects are a ...Consistent among individual variation in behavior,or animal personality,is present in a wide variety of species.This behavioral variation is maintained by both genetic and environmental factors.Parental effects are a special case of environmental variation and are expected to evolve in populations experiencing large fluctuations in their environment.They represent a non-genetic pathway by which parents can transmit information to their offspring,by modulating their personality.While it is expected that parental effects contribute to the observed personality variation,this has rarely been studied in wild populations.We used the multimammate mouse Mastomys natalensis as a model system to investigate the potential effects of maternal personality on offspring behavior.We did this by repeatedly recording the behavior of individually housed juveniles which were born and raised in the lab from wild caught females.A linear correlation,between mother and offspring in behavior,would be expected when the personality is only affected by additive genetic variation,while a more complex relationship would suggests the presence of maternal effects.We found that the personality of the mother predicted the behavior of their offspring in a non-linear pattern.Exploration behavior of mother and offspring was positively correlated,but only for slow and average exploring mothers,while this correlation became negative for fast exploring mothers.This may suggests that early maternal effects could affect personality in juvenile M.natalensis,potentially due to density-dependent and negative frequency-dependent mechanisms,and therefore contribute to the maintenance of personality variation.展开更多
We investigated host and flea species composition across different habitats during dry and rainy seasons in the Western Usambara Mountains in Tanzania.During both seasons,similarity in flea species composition increas...We investigated host and flea species composition across different habitats during dry and rainy seasons in the Western Usambara Mountains in Tanzania.During both seasons,similarity in flea species composition increased with an increase in the similarity in host species composition.Nevertheless,between-season within-habitat as well as within-season between-habitat similarity in host species composition was higher than similarity in flea species composition.Ordination of habitats according to their host and flea species composition demonstrated that the pattern of between-habitat similarity in both host and flea species composition varied seasonally.Despite the relatively rich mammal and flea fauna of the study region,the major contribution to variation in species composition between seasons and among habitats was due to a few species only.Flea assemblages on Lophuromys kilonzoi Verheyen et al.,2007 and Praomys delectorum Thomas,1910 in different habitats were equally similar in either season.In contrast,flea assemblages on Mastomys natalensis(Smith,1834)occurring in different habitats were more similar in the dry than in the rainy season,whereas the opposite was the case for fleas on Grammomys sp.In different hosts,the main differences in species composition of flea assemblages between seasons as well as among habitats were due to different flea species.Although our results support the earlier idea that parasite species composition is determined by both host species composition and habitat properties,the former appears to explain variance in flea species composition between localities in the tropics better than between localities in temperate and arid zones.展开更多
Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The ger...Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The gerbilswere collected over a 2-year period using Sherman live and Victor hold-fast snap traps in permanent 4.5-ha grids. Atotal of 664 individuals were captured over 13 650 trap nights, giving an overall trap success rate of 4.9%. Trapsuccess varied between seasons with and without crops in the field but not between habitat types. At this site, thebreeding activity of this species is seasonal. All individuals whose stomachs were analyzed ate a wide range ofitems, indicating omnivory in this species at this site;however, seeds were the most preferred diet category, with amean contribution of 50.4%, followed by arthropods, with a mean contribution of 25.7%. Other plant materialsbecame important during the very dry periods.展开更多
In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodentdamage. We used the systematic row sampling technique to provide data to achieve precision and accurac...In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodentdamage. We used the systematic row sampling technique to provide data to achieve precision and accuracy inestimations of rodent damage in maize fields at the planting and seedling stages. The actual rodent damage to maizein 15 fields, each 0.5 ha in size, in Morogoro, Tanzania, was established at the seedling stage. These data were usedto simulate the sampling intensities that would provide precision and accuracy. The variations between estimateswere plotted against the sampling intervals. The results of this study show that the relationship between averagestandardized variances and sampling intervals is linear. The heterogeneous distribution of damage in some plotscaused variations in the accuracy of the estimates between plots, but a sampling interval of five rows consistentlyproduced estimates with a variance of less than 10%. We provide a standard curve that will allow a decision to bemade on the sampling intensity as a function of required precision using the systematic row sampling technique inmaize fields.展开更多
Survival and maturation rates of female Mastomys natalensis were analysed based on a ten-year monthlycapture-recapture data set. We investigated whether direct and delayed density dependent and independent (rainfall)v...Survival and maturation rates of female Mastomys natalensis were analysed based on a ten-year monthlycapture-recapture data set. We investigated whether direct and delayed density dependent and independent (rainfall)variables accounted for the considerable variation in demographic traits. It was estimated that seasonal and annualcovariates accounted for respectively 29 and 26% of the total variation in maturation rates and respectively 17 and11% of the variation in survival rates. Explaining the between-year differences in maturation rates with annual pastrainfall or density did not improve the model fit. On the other hand we showed that maturation rates were correlatednegatively with density the previous month and positively to cumulative rainfall over the past three months.Survival estimates of both adults and subadults varied seasonally, with higher estimates during the increase phase(dry season). The subadults were characterised by a very high survival rate (> 0.95) during this phase. In thedecrease phase only minor differences were found between survival rates of subadults and adults. We found that39% of the between-year variation in survival can be explained by accumulated rainfall over the past year.展开更多
We studied associations between rodents and their arthropod ectoparasites in crop fields and household compounds in the highlands of Tigray,Northern Ethiopia.Ectoparasite infestation indices,such as percent infestatio...We studied associations between rodents and their arthropod ectoparasites in crop fields and household compounds in the highlands of Tigray,Northern Ethiopia.Ectoparasite infestation indices,such as percent infestation,mean abundance,prevalence and host preferences,were calculated for each taxon.In total,172 rodents from crop fields and 97 from household compounds were trapped.Rodent species and numbers trapped from the crop fields and household compounds were Mastomys awashensis(Lavrenchenko,Likhnova&Baskevich,1998)(88 and 44),Arvicanthis dembeensis(Ruppel,1842)(63 and 37)and Acomys sp.(21 and 16),respectively.A total of 558 insects and acarids(belonging to 11 taxa)were recovered from the rodents trapped in the crop fields,and 296 insects and acarid(belonging to 6 taxa)from the rodents trapped in the household compounds.Approximately 66%of the rodents trapped from the crop fields and 47%of those trapped from the household compounds were infested with ectoparasites.Laelaps sp.(64.9%)and Xenopsylla sp.(20.6%)comprised the highest proportion of the ectoparasites recovered in the crop fields,and the same ectoparasites,but in reverse order,comprised the highest proportions in the household compounds(Xenopsylla[50.3%]and Laelaps sp.[29%]).Our study revealed that crop fields and household compounds in the highlands share similar rodents and several ectoparasites.Furthermore,at least 1 of the rodent species and some of the ectoparasites identified in this study were reported to have posed medical and veterinary threats in other parts of Ethiopia and neighboring countries.展开更多
Studies of populations of the multimammate rat Mastomys natalensis in Morogoro, Tanzania, show that soil textureappears to influence the population abundance and distribution of these rats in agricultural fields. The ...Studies of populations of the multimammate rat Mastomys natalensis in Morogoro, Tanzania, show that soil textureappears to influence the population abundance and distribution of these rats in agricultural fields. The lowest rodentpopulation abundance was found on sandy clay soils (F(2, 5) = 8.42;P = 0.025). The population abundances of M.natalensis on sandy clay loam and sandy loam soils did not differ significantly (P ≤ 0.05), possibly because thesesoils have a very similar texture. The results of this study suggest that M. natalensis prefers loam-textured soilswith a high percentage of sand, which are probably better than clay soils for burrowing and nesting, particularly inthe rainy season. The lower preference for clay soils is probably related to the poor aeration in these soils and thewaterlogging that occurs during the wet season.展开更多
文摘The pattern of plague endemicity in Tanzania is characterized by continuous re-appearance of the disease in some locations,while in other neighbouring villages the disease has never or seldom been observed.To understand the reasons for this pattern,we studied small mammal and flea species composition,diversity and relative abundances in two plague-endemic and two plague-free locations.We asked(a)whether fleas more abundant in plague-endemic locations differ in their characteristic abundance and the degree of their host specificity from fleas more abundant in plague-free locations and(b)whether hosts most abundant in plague-endemic locations differ in the diversity of their flea assemblages from hosts most abundant in plague-free locations.We characterized(a)each host species by species richness and degree of taxonomic relatedness of its flea assemblages and(b)each flea species by its mean abundance and size,and degree of taxonomic relatedness of its host spectrum and compared their relative abundances between locations.No significant difference between plague-endemic and plague-free locations in either host density or any variable related to flea abundance or diversity was found.However,there was marginally significant effect of taxonomic distinctness of a flea assemblage harboured by a host on its probability to be more abundant in either plague-endemic or plague-free locations.Furthermore,hosts more abundant in plague-endemic locations tended to harbour closely-related fleas.Finally,while opportunistic and specialist fleas were equally distributed in both sets of locations,fleas exploiting distantly-related hosts were found mainly in plague-free locations during the rainy season.We suggest that the observed patterns might arise due to seasonal and spatial differences in local microclimatic conditions and landscape connectivity.
基金This work was part of the Wildlife Population Ecology(WiPE)project under the Department of Wildlife Management at Sokoine University of Agriculture,supported by the Flemish VLIR-UOS Own Initiatives program.The authors acknowledge the cooperation from the Tanzania Wildlife Research Institute(TAWIRI)for providing permits to conduct the research in Saadani National Park,The Tanzania National Parks(TANAPA).We are especially grateful to the Saadani National Park staff,and Miss Halima Penga,the Park Ecologist for her assistance whenever needed.We appreciate the excellent field assistance from Omari Kibwana,Dege Hussein and Samwel Shaba and the commitment they extended during the whole study。
文摘The lesser pouched rat,Beamys hindei,is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa.The ecology of this species and its current distribution in coastal forests is not well known.Therefore,we conducted a study in selected coastal forests to assess the current distribution of the species and to investigate the population ecology in terms of abundance fluctuations and demographic patterns.Assessments of the species distribution were conducted in 5 forests through trapping with Sherman live traps.Data on ecology were obtained from monthly capture–mark–recapture studies conducted for 5 consecutive nights per month in two 1 ha grids set in Zaraninge Forest over a 2-year period.The results indicate the presence of B.hindei in 3 forests where it was not previously recorded.The population abundance estimates ranged from 1 to 40 animals per month,with high numbers recorded during rainy seasons.Reproduction patterns and sex ratios did not differ between months.Survival estimates were not influenced by season,and recruitment was low,with growth rate estimates of 1 animal per month.These estimates suggest a stable population of B.hindei in Zaraninge Forest.Further studies are recommended to establish the home range,diet and burrowing behavior of the species in coastal forests in East Africa.
基金B.V.B.was funded by the Ph.D.fellowship from the Research Foundation Flanders(FWO)(grant ID:11A0817N).
文摘Consistent among individual variation in behavior,or animal personality,is present in a wide variety of species.This behavioral variation is maintained by both genetic and environmental factors.Parental effects are a special case of environmental variation and are expected to evolve in populations experiencing large fluctuations in their environment.They represent a non-genetic pathway by which parents can transmit information to their offspring,by modulating their personality.While it is expected that parental effects contribute to the observed personality variation,this has rarely been studied in wild populations.We used the multimammate mouse Mastomys natalensis as a model system to investigate the potential effects of maternal personality on offspring behavior.We did this by repeatedly recording the behavior of individually housed juveniles which were born and raised in the lab from wild caught females.A linear correlation,between mother and offspring in behavior,would be expected when the personality is only affected by additive genetic variation,while a more complex relationship would suggests the presence of maternal effects.We found that the personality of the mother predicted the behavior of their offspring in a non-linear pattern.Exploration behavior of mother and offspring was positively correlated,but only for slow and average exploring mothers,while this correlation became negative for fast exploring mothers.This may suggests that early maternal effects could affect personality in juvenile M.natalensis,potentially due to density-dependent and negative frequency-dependent mechanisms,and therefore contribute to the maintenance of personality variation.
文摘We investigated host and flea species composition across different habitats during dry and rainy seasons in the Western Usambara Mountains in Tanzania.During both seasons,similarity in flea species composition increased with an increase in the similarity in host species composition.Nevertheless,between-season within-habitat as well as within-season between-habitat similarity in host species composition was higher than similarity in flea species composition.Ordination of habitats according to their host and flea species composition demonstrated that the pattern of between-habitat similarity in both host and flea species composition varied seasonally.Despite the relatively rich mammal and flea fauna of the study region,the major contribution to variation in species composition between seasons and among habitats was due to a few species only.Flea assemblages on Lophuromys kilonzoi Verheyen et al.,2007 and Praomys delectorum Thomas,1910 in different habitats were equally similar in either season.In contrast,flea assemblages on Mastomys natalensis(Smith,1834)occurring in different habitats were more similar in the dry than in the rainy season,whereas the opposite was the case for fleas on Grammomys sp.In different hosts,the main differences in species composition of flea assemblages between seasons as well as among habitats were due to different flea species.Although our results support the earlier idea that parasite species composition is determined by both host species composition and habitat properties,the former appears to explain variance in flea species composition between localities in the tropics better than between localities in temperate and arid zones.
文摘Seasonal abundance, reproductive biology and feeding ecology of the bushveld gerbil Tatera leucogaster (Peters,1852) were investigated in small-scale maize field–fallow land mosaics in south-western Tanzania. The gerbilswere collected over a 2-year period using Sherman live and Victor hold-fast snap traps in permanent 4.5-ha grids. Atotal of 664 individuals were captured over 13 650 trap nights, giving an overall trap success rate of 4.9%. Trapsuccess varied between seasons with and without crops in the field but not between habitat types. At this site, thebreeding activity of this species is seasonal. All individuals whose stomachs were analyzed ate a wide range ofitems, indicating omnivory in this species at this site;however, seeds were the most preferred diet category, with amean contribution of 50.4%, followed by arthropods, with a mean contribution of 25.7%. Other plant materialsbecame important during the very dry periods.
文摘In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodentdamage. We used the systematic row sampling technique to provide data to achieve precision and accuracy inestimations of rodent damage in maize fields at the planting and seedling stages. The actual rodent damage to maizein 15 fields, each 0.5 ha in size, in Morogoro, Tanzania, was established at the seedling stage. These data were usedto simulate the sampling intensities that would provide precision and accuracy. The variations between estimateswere plotted against the sampling intervals. The results of this study show that the relationship between averagestandardized variances and sampling intervals is linear. The heterogeneous distribution of damage in some plotscaused variations in the accuracy of the estimates between plots, but a sampling interval of five rows consistentlyproduced estimates with a variance of less than 10%. We provide a standard curve that will allow a decision to bemade on the sampling intensity as a function of required precision using the systematic row sampling technique inmaize fields.
文摘Survival and maturation rates of female Mastomys natalensis were analysed based on a ten-year monthlycapture-recapture data set. We investigated whether direct and delayed density dependent and independent (rainfall)variables accounted for the considerable variation in demographic traits. It was estimated that seasonal and annualcovariates accounted for respectively 29 and 26% of the total variation in maturation rates and respectively 17 and11% of the variation in survival rates. Explaining the between-year differences in maturation rates with annual pastrainfall or density did not improve the model fit. On the other hand we showed that maturation rates were correlatednegatively with density the previous month and positively to cumulative rainfall over the past three months.Survival estimates of both adults and subadults varied seasonally, with higher estimates during the increase phase(dry season). The subadults were characterised by a very high survival rate (> 0.95) during this phase. In thedecrease phase only minor differences were found between survival rates of subadults and adults. We found that39% of the between-year variation in survival can be explained by accumulated rainfall over the past year.
文摘We studied associations between rodents and their arthropod ectoparasites in crop fields and household compounds in the highlands of Tigray,Northern Ethiopia.Ectoparasite infestation indices,such as percent infestation,mean abundance,prevalence and host preferences,were calculated for each taxon.In total,172 rodents from crop fields and 97 from household compounds were trapped.Rodent species and numbers trapped from the crop fields and household compounds were Mastomys awashensis(Lavrenchenko,Likhnova&Baskevich,1998)(88 and 44),Arvicanthis dembeensis(Ruppel,1842)(63 and 37)and Acomys sp.(21 and 16),respectively.A total of 558 insects and acarids(belonging to 11 taxa)were recovered from the rodents trapped in the crop fields,and 296 insects and acarid(belonging to 6 taxa)from the rodents trapped in the household compounds.Approximately 66%of the rodents trapped from the crop fields and 47%of those trapped from the household compounds were infested with ectoparasites.Laelaps sp.(64.9%)and Xenopsylla sp.(20.6%)comprised the highest proportion of the ectoparasites recovered in the crop fields,and the same ectoparasites,but in reverse order,comprised the highest proportions in the household compounds(Xenopsylla[50.3%]and Laelaps sp.[29%]).Our study revealed that crop fields and household compounds in the highlands share similar rodents and several ectoparasites.Furthermore,at least 1 of the rodent species and some of the ectoparasites identified in this study were reported to have posed medical and veterinary threats in other parts of Ethiopia and neighboring countries.
文摘Studies of populations of the multimammate rat Mastomys natalensis in Morogoro, Tanzania, show that soil textureappears to influence the population abundance and distribution of these rats in agricultural fields. The lowest rodentpopulation abundance was found on sandy clay soils (F(2, 5) = 8.42;P = 0.025). The population abundances of M.natalensis on sandy clay loam and sandy loam soils did not differ significantly (P ≤ 0.05), possibly because thesesoils have a very similar texture. The results of this study suggest that M. natalensis prefers loam-textured soilswith a high percentage of sand, which are probably better than clay soils for burrowing and nesting, particularly inthe rainy season. The lower preference for clay soils is probably related to the poor aeration in these soils and thewaterlogging that occurs during the wet season.