The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,...The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,which provides the possibility of the increase of the vole's population. Reclaiming farmland from lake via building cofferdams,eliminating snails by building cofferdams for eradicating schistosomiasis,and over-hunting predators in the region cause the voles becoming a pest after the 1970s. In recent years,the Three Gorges Project and the conversion from farmland into lake have had deep impacts on the environment in the lake region. The dispatching of the down flow rate by the project has induced the expansion of the low and medium level beaches in the lake region,while converting farmland into lake directly has induced the expansion of the lake beaches,both of which have expanded the potential habitats of the vole's population. Therefore,more attention should be paid to the quantitative variation trend of the vole's population in the future.展开更多
The Yangtze vole(Microtus fortis Buechner,1889)is a small herbivore species that inhabits lake beaches in the Dongting Lake region along the Yangtze River in Southern China.Its population shows strong oscillations dur...The Yangtze vole(Microtus fortis Buechner,1889)is a small herbivore species that inhabits lake beaches in the Dongting Lake region along the Yangtze River in Southern China.Its population shows strong oscillations during the wet season due to summer precipitation-induced immigration away from the lake into adjacent rice fields.The effect of El Niño-Southern Oscillation-driven precipitation on population abundance and growth of the vole species is not fully understood.We undertook an analysis of the combined data of 4 time series covering 1981–2006 from 4 different sites and a separate analysis on a single time series(1981–2006)from one site.Our results demonstrate that a dual effect of El Niño-Southern Oscillation-driven precipitation on the population abundance of voles is timedependent:precipitation in the current year has a positive effect,whereas precipitation in the previous year has a negative effect.The dual effect of precipitation on vole population is well explained by the unique interactions among vole population,precipitation water level and the lake beach habitat around Dongting Lake.We found that drier than average weather of the previous year benefited voles because their breeding habitats,lake beaches,were exposed for long stretches of time.Wet weather was found to increase the number of voles inhabiting rice fields because as the water level of the lake rose they were forced from beaches into surrounding rice fields.Summer precipitation in the Dongting Lake region was found to be positively associated with the sea surface temperature(SST)of the eastern tropical Pacific Ocean of the previous year and winter SST and spring SST of the current year.Annual rates of increase in the vole population of the reconstructed time series are negatively associated with the vole abundance and autumn precipitation of the previous year and winter precipitation of the current years.These results suggest that both extrinsic and density-dependent intrinsic factors may affect population dynamics of the Yangtze voles.展开更多
Microtus fortis is the only mammalian host that exhibits intrinsic resistance against Schistosoma japonicum infection.However,the underlying molecular mechanisms of this resistance are not yet known.Here,we perform th...Microtus fortis is the only mammalian host that exhibits intrinsic resistance against Schistosoma japonicum infection.However,the underlying molecular mechanisms of this resistance are not yet known.Here,we perform the first de novo genome assembly of M.fortis,comprehensive gene annotation analysis,and evolution analysis.Furthermore,we compare the recovery rate of schistosomes,pathological changes,and liver transcriptomes between M.fortis and mice at different time points after infection.We observe that the time and type of immune response in M.fortis are different from those in mice.M.fortis activates immune and inflammatory responses on the 10th day post infection,such as leukocyte extravasation,antibody activation,Fc-gamma receptor-mediated phagocytosis,and the interferon signaling cascade,which play important roles in preventing the development of schistosomes.In contrast,an intense immune response occurrs in mice at the late stages of infection and could not eliminate schistosomes.Infected mice suffer severe pathological injury and continuous decreases in cell cycle,lipid metabolism,and other functions.Our findings offer new insights into the intrinsic resistance mechanism of M.fortis against schistosome infection.The genome sequence also provides the basis for future studies of other important traits in M.fortis.展开更多
The Lusitanian(Microtus lusitanicus)and the Mediterranean(Microtus duodecimcostatus)pine voles are recently diverged sister species endemic of the Iberian Peninsula that can be identified with ecological and morphologi...The Lusitanian(Microtus lusitanicus)and the Mediterranean(Microtus duodecimcostatus)pine voles are recently diverged sister species endemic of the Iberian Peninsula that can be identified with ecological and morphological characters,but in areas where the 2 species co-occur,species designation may be difficult.Genetic discrimination between M.lusitanicus and M.duodecimcostatus has not been achieved yet possibly because of their estimated re-cent split and an evolutionary history that includes inter-species geneflow.Following our previous observations on exons 5–7 of the p53 gene,here we analyze the potential use of the p53 genomic region as a discrimination marker of these species by extending our analyses to several kb upstream and downstream of the p53 gene and charac-terizing the degree of genetic differentiation in 7 markers within this region.Additionally,we fully sequenced the P53 protein of both species.We observed:(i)generally high differentiation in this region;(ii)M.duodecimcostatus showed in general higher values of nucleotide and haplotype diversities;(iii)the concatenated phylogenetic tree separates the 2 species;(iv)the 2 P53 proteins only differ in 1 amino acid;(v)4 of the markers,2 in p53,one in Atp1b2,and another in Wrap53,contain species-specific genetic variation thus allowing a reliable discrimination between specimens from both species,irrespective of sampling location or introgression status.We provide ad-ditional data on the putative role of p53 in the evolution of these species and present researchers with a fast and cost-effective resource for M.lusitanicus and M.duodecimcostatus identification.展开更多
The Lusitanian and the Mediterranean pine voles(Microtus lusitanicus Gerbe,1879 and Microtus duodecimcostatus de Selys-Longchamps,1839)are fossorial sister species and have an allopatric pattern of distribution in Por...The Lusitanian and the Mediterranean pine voles(Microtus lusitanicus Gerbe,1879 and Microtus duodecimcostatus de Selys-Longchamps,1839)are fossorial sister species and have an allopatric pattern of distribution in Portugal,which includes a potential sympatry area in the centre of the country.The present study aimed to determine the validity of using presence signs in the field for discrimination of the two species in an area of sympatry(Northern Alentejo)and the characteristics that achieve the best classification accuracy.A total of 175 trapping plots were sampled across the study area.Prior to the set up of traps,ten presence signs were randomly selected for measure-ments of four variables:proportion of soil mounds,mean diameter of mounds,proportion of burrow openings and mean diameter of burrow openings.On the basis of a classification tree analysis,results showed that presence signs can be used to discriminate plots inhabited by one or the other species in the studied sympatry area.The character-istic that most accurately enables species identification is the proportion of burrow openings:for every ten pres-ence signs found in a plot,if more than eight have an opening,then it is inhabited by M.lusitanicus(i.e.mostly burrow openings with few or no mounds present);if eight or fewer have an opening,M.duodecimcostatus is present(i.e.mostly mounds with few or no burrow openings).展开更多
No-till farming is an important approach to sustainable agriculture because it can conserve soil and water resources.Unfortunately, rodent populations can thrive under no-till conditions because burrow systems are not...No-till farming is an important approach to sustainable agriculture because it can conserve soil and water resources.Unfortunately, rodent populations can thrive under no-till conditions because burrow systems are not disrupted byannual plowing and plant residues build-up on the surface, providing cover and insulation. This can result in substantialcrop damage. We assessed rodent populations, habitat use, food habits, and crop damage in a no-till croppingsystem in Washington, USA. We also conducted preliminary trials of methods to reduce rodent populationsand crop damage. In the fall, many more rodents were captured in fields with unharvested crops than in fieldscontaining only plant stubble, suggesting that rodents leave fields after crop harvest, providing that suitable habitatsare nearby, even when adequate cover is still available in harvested crop fields. By spring, the number of volescaptured was much lower relative to fall. Despite this, capture rates were much higher in surrounding permanentgrass areas than in crop (barley, wheat, pea) fields, suggesting that these grassy areas serve as refugia for rodents.Furthermore, the permanent grass cover type was the landscape variable most associated with rodent capture rates.In three winter pea fields, rodents removed 5–15% of the pea plants over winter. Examination of stomach contentsrevealed that voles mainly fed on grain plants in spring, but that their diet was more diversified in fall. Deer micefed heavily on grain plants in both spring and fall, but also used insects as food. Metal barrier exclosures (9 m × 9m), extending above and below ground, did not prevent access by rodents. Rodent populations in areas treated withzinc phosphide on grain were comparable to untreated areas 1 year after application of the rodenticide, perhaps becauseof immigration and recruitment, suggesting that baiting does not provide a long-term solution to rodent damagein no-till agricultural fields.展开更多
Browsing by large herbivores might either increase or decrease preference for the plant by other herbivores,depending on the plant response.Using a cafeteria test,we studied the preference by root voles(Microtus oecon...Browsing by large herbivores might either increase or decrease preference for the plant by other herbivores,depending on the plant response.Using a cafeteria test,we studied the preference by root voles(Microtus oeconomus[Pallas,1776])for bilberry(Vaccinium myrtillus L.)previously subjected to 4 levels of simulated moose(Alces alces[Linnaeus,1758])density.The different levels of moose density were simulated at population densities relevant for Fennoscandian conditions,in exclosures situated along a site productivity gradient.We expected:(i)voles to prefer bilberry from high productivity sites over low productivity sites;(ii)voles to prefer browsed bilberry,if plants allocate resources to compensatory growth or to avoid browsed bilberry if plants allocate resources to defense;(iii)these effects to increase with increasing simulated moose density;and(iv)the concentration of plant chemicals and the plant morphology to explain vole preference.Specifically,we predicted that voles would prefer:(i)plants with high nitrogen content;(ii)plants with low content of defensive substances;and(iii)tall plants with long shoots.Voles preferred bilberry from the high productivity sites compared to the low productivity sites.We also found an interaction between site productivity and simulated moose density,where voles preferred unbrowsed plants at low productivity sites and intermediate levels of browsing at high productivity sites.There was no effect of plant chemistry or morphology on vole preference.We conclude that moose browsing impacts the food preference of voles.With the current high densities of moose in Fennoscandia,this could potentially influence vole food selection and population dynamics over large geographical areas.展开更多
Bait markers are indispensable for ecological research but in small mammals,most markers are invasive,expensive and do not enable quantitative analyses of consumption.Ethyl-iophenoxic acid(Et-IPA)is a non-toxic,quanti...Bait markers are indispensable for ecological research but in small mammals,most markers are invasive,expensive and do not enable quantitative analyses of consumption.Ethyl-iophenoxic acid(Et-IPA)is a non-toxic,quantitative bait marker,which has been used for studying bait uptake in several carnivores and ungulates.We developed a bait with Et-IPA,assessed its palatability to common voles(Microtus arvalis),and determined the dose-residue-relation for this important agricultural pest rodent species.Et-IPA concentrations of 40 to 1280μg Et-IPA per g bait were applied to wheat using sunflower oil or polyethylene glycol 300 as potential carriers.In a laboratory study,common voles were offered the bait and blood samples were collected 1,7,and 14 days after consumption.The samples were analyzed with LC-ESI-MS/MS for blood residues of Et-IPA.Sunflower-oil was the most suitable bait carrier.Et-IPA seemed to be palatable to common voles at all test concentrations.Dose-dependent residues could be detected in blood samples in a dose-dependent manner and up to 14 days after uptake enabling generation of a calibration curve of the dose-residue relationship.Et-IPA was present in common vole blood for at least 14 days,but there was dissipation by 33–37%depending on dose.Et-IPA meets many criteria for an“ideal”quantitative bait marker for use in futurefield studies on common voles and possibly other small mammal species.展开更多
Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctu...Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctuations to the composition of the landscape.It states that as ROMPA decreases(fragmentation increases),vole population fluctuations will increase(including the tendency to display multi-annual cycles in abundance)because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season.To date,only comparative observations in the field have supported the hypothesis.This paper reports the results of the first experimental test.I used prairie voles,Microtus ochrogaster,and mowed grassland to create model landscapes with 3 levels of ROMPA(high with 25%mowed,medium with 50%mowed and low with 75%mowed).As ROMPA decreased,distances between patches of favorable habitat(high cover)increased owing to a greater proportion of unfavorable(mowed)habitat.Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed(inversely density dependent emigration and,as ROMPA decreased,increased per capita mortality and decreased per capita movement between optimal patches).Nevertheless,contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability,5 years of trapping indicated that variability was lowest with medium ROMPA.The design of field experiments may never be perfect,but these results indicate that the ROMPA hypothesis needs further rigorous testing.展开更多
基金Supported by the National Natural Science Foundation(30870402,31170396)Key Knowledge Innovation Project of Chinese Academy of Sciences(KSCX-EW-N-05)
文摘The outbreak of Yantze vole ( Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches,because the deposition of lake sediments results in the expansion of lake beaches,which provides the possibility of the increase of the vole's population. Reclaiming farmland from lake via building cofferdams,eliminating snails by building cofferdams for eradicating schistosomiasis,and over-hunting predators in the region cause the voles becoming a pest after the 1970s. In recent years,the Three Gorges Project and the conversion from farmland into lake have had deep impacts on the environment in the lake region. The dispatching of the down flow rate by the project has induced the expansion of the low and medium level beaches in the lake region,while converting farmland into lake directly has induced the expansion of the lake beaches,both of which have expanded the potential habitats of the vole's population. Therefore,more attention should be paid to the quantitative variation trend of the vole's population in the future.
基金supported by the State Basic Research Program of Ministry of Science and Technology(2007CB109100)CAS project(GJHZ 200810)the ISZS international research program Biological Consequences of Global Change(BCGC)sponsored by Bureau of International Cooperation,Chinese Academy of Sciences(GJHZ200810).
文摘The Yangtze vole(Microtus fortis Buechner,1889)is a small herbivore species that inhabits lake beaches in the Dongting Lake region along the Yangtze River in Southern China.Its population shows strong oscillations during the wet season due to summer precipitation-induced immigration away from the lake into adjacent rice fields.The effect of El Niño-Southern Oscillation-driven precipitation on population abundance and growth of the vole species is not fully understood.We undertook an analysis of the combined data of 4 time series covering 1981–2006 from 4 different sites and a separate analysis on a single time series(1981–2006)from one site.Our results demonstrate that a dual effect of El Niño-Southern Oscillation-driven precipitation on the population abundance of voles is timedependent:precipitation in the current year has a positive effect,whereas precipitation in the previous year has a negative effect.The dual effect of precipitation on vole population is well explained by the unique interactions among vole population,precipitation water level and the lake beach habitat around Dongting Lake.We found that drier than average weather of the previous year benefited voles because their breeding habitats,lake beaches,were exposed for long stretches of time.Wet weather was found to increase the number of voles inhabiting rice fields because as the water level of the lake rose they were forced from beaches into surrounding rice fields.Summer precipitation in the Dongting Lake region was found to be positively associated with the sea surface temperature(SST)of the eastern tropical Pacific Ocean of the previous year and winter SST and spring SST of the current year.Annual rates of increase in the vole population of the reconstructed time series are negatively associated with the vole abundance and autumn precipitation of the previous year and winter precipitation of the current years.These results suggest that both extrinsic and density-dependent intrinsic factors may affect population dynamics of the Yangtze voles.
基金This work was supported by the Key Project in the National Science&Technology Pillar Program from the Ministry of Science and Technology(2015BAI09B04)the National Natural Science Foundation of China(31872256,31472188)+2 种基金the National Key Research and Development Program of China(2017YFD0501306)the Science and Technology Service Network Initiative of Chinese Academy of Sciences(KFJ-STS-QYZD-126,ZDBS-SSW-DQC-02)CAS Youth Innovation Promotion Association,and SA-SIBS Scholarship Program.
文摘Microtus fortis is the only mammalian host that exhibits intrinsic resistance against Schistosoma japonicum infection.However,the underlying molecular mechanisms of this resistance are not yet known.Here,we perform the first de novo genome assembly of M.fortis,comprehensive gene annotation analysis,and evolution analysis.Furthermore,we compare the recovery rate of schistosomes,pathological changes,and liver transcriptomes between M.fortis and mice at different time points after infection.We observe that the time and type of immune response in M.fortis are different from those in mice.M.fortis activates immune and inflammatory responses on the 10th day post infection,such as leukocyte extravasation,antibody activation,Fc-gamma receptor-mediated phagocytosis,and the interferon signaling cascade,which play important roles in preventing the development of schistosomes.In contrast,an intense immune response occurrs in mice at the late stages of infection and could not eliminate schistosomes.Infected mice suffer severe pathological injury and continuous decreases in cell cycle,lipid metabolism,and other functions.Our findings offer new insights into the intrinsic resistance mechanism of M.fortis against schistosome infection.The genome sequence also provides the basis for future studies of other important traits in M.fortis.
基金Fundação para a Ciência e a Tecnologia/Ministério da Ciência,Tecnologia e Ensino Superior(FCT/MCTES)for the financial support to CESAM(UIDP/50017/2020+UIDB/50017/2020)through national funds.ASQ and JPT are funded by national funds(OE),through FCT。
文摘The Lusitanian(Microtus lusitanicus)and the Mediterranean(Microtus duodecimcostatus)pine voles are recently diverged sister species endemic of the Iberian Peninsula that can be identified with ecological and morphological characters,but in areas where the 2 species co-occur,species designation may be difficult.Genetic discrimination between M.lusitanicus and M.duodecimcostatus has not been achieved yet possibly because of their estimated re-cent split and an evolutionary history that includes inter-species geneflow.Following our previous observations on exons 5–7 of the p53 gene,here we analyze the potential use of the p53 genomic region as a discrimination marker of these species by extending our analyses to several kb upstream and downstream of the p53 gene and charac-terizing the degree of genetic differentiation in 7 markers within this region.Additionally,we fully sequenced the P53 protein of both species.We observed:(i)generally high differentiation in this region;(ii)M.duodecimcostatus showed in general higher values of nucleotide and haplotype diversities;(iii)the concatenated phylogenetic tree separates the 2 species;(iv)the 2 P53 proteins only differ in 1 amino acid;(v)4 of the markers,2 in p53,one in Atp1b2,and another in Wrap53,contain species-specific genetic variation thus allowing a reliable discrimination between specimens from both species,irrespective of sampling location or introgression status.We provide ad-ditional data on the putative role of p53 in the evolution of these species and present researchers with a fast and cost-effective resource for M.lusitanicus and M.duodecimcostatus identification.
基金support was provided by Funda玢o para a Ciência e Tecnologia(SAPIENS Project POCI/BIA-BDE/57053/2004 and a PhD grant PRAXIS/SFRH/BD/21403/2005).
文摘The Lusitanian and the Mediterranean pine voles(Microtus lusitanicus Gerbe,1879 and Microtus duodecimcostatus de Selys-Longchamps,1839)are fossorial sister species and have an allopatric pattern of distribution in Portugal,which includes a potential sympatry area in the centre of the country.The present study aimed to determine the validity of using presence signs in the field for discrimination of the two species in an area of sympatry(Northern Alentejo)and the characteristics that achieve the best classification accuracy.A total of 175 trapping plots were sampled across the study area.Prior to the set up of traps,ten presence signs were randomly selected for measure-ments of four variables:proportion of soil mounds,mean diameter of mounds,proportion of burrow openings and mean diameter of burrow openings.On the basis of a classification tree analysis,results showed that presence signs can be used to discriminate plots inhabited by one or the other species in the studied sympatry area.The character-istic that most accurately enables species identification is the proportion of burrow openings:for every ten pres-ence signs found in a plot,if more than eight have an opening,then it is inhabited by M.lusitanicus(i.e.mostly burrow openings with few or no mounds present);if eight or fewer have an opening,M.duodecimcostatus is present(i.e.mostly mounds with few or no burrow openings).
文摘No-till farming is an important approach to sustainable agriculture because it can conserve soil and water resources.Unfortunately, rodent populations can thrive under no-till conditions because burrow systems are not disrupted byannual plowing and plant residues build-up on the surface, providing cover and insulation. This can result in substantialcrop damage. We assessed rodent populations, habitat use, food habits, and crop damage in a no-till croppingsystem in Washington, USA. We also conducted preliminary trials of methods to reduce rodent populationsand crop damage. In the fall, many more rodents were captured in fields with unharvested crops than in fieldscontaining only plant stubble, suggesting that rodents leave fields after crop harvest, providing that suitable habitatsare nearby, even when adequate cover is still available in harvested crop fields. By spring, the number of volescaptured was much lower relative to fall. Despite this, capture rates were much higher in surrounding permanentgrass areas than in crop (barley, wheat, pea) fields, suggesting that these grassy areas serve as refugia for rodents.Furthermore, the permanent grass cover type was the landscape variable most associated with rodent capture rates.In three winter pea fields, rodents removed 5–15% of the pea plants over winter. Examination of stomach contentsrevealed that voles mainly fed on grain plants in spring, but that their diet was more diversified in fall. Deer micefed heavily on grain plants in both spring and fall, but also used insects as food. Metal barrier exclosures (9 m × 9m), extending above and below ground, did not prevent access by rodents. Rodent populations in areas treated withzinc phosphide on grain were comparable to untreated areas 1 year after application of the rodenticide, perhaps becauseof immigration and recruitment, suggesting that baiting does not provide a long-term solution to rodent damagein no-till agricultural fields.
基金This study was funded by Hedmark University College.The moose simulation experiment,including sampling of bilberry used in this experiment,was financed by the Swedish Research Council for Environmental,Agricultural Sciences and Spatial Planning,and the Swedish Environmental Protection Agency(grants to I-L Persson and K Danell)The forest companies Assi Domän/Sveaskog and Holmen Skog kindly allowed us to work on their land.The study was conducted in accordance with current Norwegian and Swedish laws,under the necessary permits(2007/11612 ART-VI-ID and STFDU1058).
文摘Browsing by large herbivores might either increase or decrease preference for the plant by other herbivores,depending on the plant response.Using a cafeteria test,we studied the preference by root voles(Microtus oeconomus[Pallas,1776])for bilberry(Vaccinium myrtillus L.)previously subjected to 4 levels of simulated moose(Alces alces[Linnaeus,1758])density.The different levels of moose density were simulated at population densities relevant for Fennoscandian conditions,in exclosures situated along a site productivity gradient.We expected:(i)voles to prefer bilberry from high productivity sites over low productivity sites;(ii)voles to prefer browsed bilberry,if plants allocate resources to compensatory growth or to avoid browsed bilberry if plants allocate resources to defense;(iii)these effects to increase with increasing simulated moose density;and(iv)the concentration of plant chemicals and the plant morphology to explain vole preference.Specifically,we predicted that voles would prefer:(i)plants with high nitrogen content;(ii)plants with low content of defensive substances;and(iii)tall plants with long shoots.Voles preferred bilberry from the high productivity sites compared to the low productivity sites.We also found an interaction between site productivity and simulated moose density,where voles preferred unbrowsed plants at low productivity sites and intermediate levels of browsing at high productivity sites.There was no effect of plant chemistry or morphology on vole preference.We conclude that moose browsing impacts the food preference of voles.With the current high densities of moose in Fennoscandia,this could potentially influence vole food selection and population dynamics over large geographical areas.
基金funded by the German Federal Ministry of Food and Agriculture due to a parliamentary resolution within the federal program“Organic farming and other forms of sustainable agriculture”(file#2815NA113)All animal experimentation was conducted in accordance with EU and federal legislation(file#No.81-02.04.2019.A246).
文摘Bait markers are indispensable for ecological research but in small mammals,most markers are invasive,expensive and do not enable quantitative analyses of consumption.Ethyl-iophenoxic acid(Et-IPA)is a non-toxic,quantitative bait marker,which has been used for studying bait uptake in several carnivores and ungulates.We developed a bait with Et-IPA,assessed its palatability to common voles(Microtus arvalis),and determined the dose-residue-relation for this important agricultural pest rodent species.Et-IPA concentrations of 40 to 1280μg Et-IPA per g bait were applied to wheat using sunflower oil or polyethylene glycol 300 as potential carriers.In a laboratory study,common voles were offered the bait and blood samples were collected 1,7,and 14 days after consumption.The samples were analyzed with LC-ESI-MS/MS for blood residues of Et-IPA.Sunflower-oil was the most suitable bait carrier.Et-IPA seemed to be palatable to common voles at all test concentrations.Dose-dependent residues could be detected in blood samples in a dose-dependent manner and up to 14 days after uptake enabling generation of a calibration curve of the dose-residue relationship.Et-IPA was present in common vole blood for at least 14 days,but there was dissipation by 33–37%depending on dose.Et-IPA meets many criteria for an“ideal”quantitative bait marker for use in futurefield studies on common voles and possibly other small mammal species.
文摘Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctuations to the composition of the landscape.It states that as ROMPA decreases(fragmentation increases),vole population fluctuations will increase(including the tendency to display multi-annual cycles in abundance)because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season.To date,only comparative observations in the field have supported the hypothesis.This paper reports the results of the first experimental test.I used prairie voles,Microtus ochrogaster,and mowed grassland to create model landscapes with 3 levels of ROMPA(high with 25%mowed,medium with 50%mowed and low with 75%mowed).As ROMPA decreased,distances between patches of favorable habitat(high cover)increased owing to a greater proportion of unfavorable(mowed)habitat.Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed(inversely density dependent emigration and,as ROMPA decreased,increased per capita mortality and decreased per capita movement between optimal patches).Nevertheless,contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability,5 years of trapping indicated that variability was lowest with medium ROMPA.The design of field experiments may never be perfect,but these results indicate that the ROMPA hypothesis needs further rigorous testing.
