The role of seasonality in vole cycles

1986 ◽  
Vol 64 (12) ◽  
pp. 2871-2872 ◽  
Author(s):  
Richard S. Ostfeld ◽  
Robert H. Tamarin
Keyword(s):  
Population Density ◽  
Food Availability ◽  
Population Fluctuations ◽  
High Population Density ◽  
Vole Population ◽  
Seasonal Fluctuations ◽  
Microtus Californicus ◽  
Vole Cycles ◽  
California Vole

We examined the assertion that seasonal fluctuations in food availability are necessary for vole cycles to take place by studying the dynamics of a California vole (Microtus californicus) population inhabiting a relatively aseasonal environment. That population was one of the most stable (noncyclic) microtine populations yet described. Reproduction was comparatively aseasonal but appeared to be suppressed at high population density. We suggest that the role of seasonality in vole population fluctuations deserves further study.

Differences in growth rate, body condition, habitat use and food availability between island and mainland lizard populations ofAnolis nebulosusin Jalisco, Mexico

2014 ◽  
Vol 30 (5) ◽  
pp. 493-501 ◽  
Author(s):  
Héctor Hugo Siliceo-Cantero ◽  
Andrés García
Keyword(s):  
Growth Rate ◽  
Habitat Use ◽  
Food Availability ◽  
Body Condition ◽  
Food Supply ◽  
Geographic Isolation ◽  
Seasonal Fluctuations ◽  
Continental Population ◽  
Two Populations

Abstract:Lizards of the genusAnolishave been widely studied, however, little is known about the effects of environmental seasonality, food availability and geographic isolation on body condition, growth rate and habitat use of lizards. The existence of an insular and a continental population ofAnolis nebulosus(clouded anole), separated by only 0.47 km, represents an ideal opportunity to address this topic. We compared seasonal fluctuations in food availability (arthropod density) for anoles, as well as body condition, growth rate and habitat use in the two populations. Food availability throughout the year was sampled every 2 mo by trapping arthropods at each site. Lizards were also monitored and measured every 2 mo by surveying three quadrats in each site over 2 y giving a total of 30 visits for each quadrat. Results suggested that composition and density of food supply was similar for the two populations. Nevertheless, food supply responded to seasonality of rainfall, with an increase of 1.5 times during the rainy season. Despite similarity in food availability, insular anoles had body condition that was 5–10 times better, with growth rate twice as fast, and used similar perches. The role of predation, and inter- and intraspecific competition are discussed as possible drivers.

Community based design approach as initial stage to promote urban composting from a Hill Station of the Philippines

2019 ◽  
Author(s):  
Marcelino Jr Lunag ◽  
Jessie C. Elauria ◽  
Juanito D. Burguillos
Keyword(s):  
Population Density ◽  
Community Involvement ◽  
The Philippines ◽  
Design Stage ◽  
High Population Density ◽  
Community Based ◽  
Hill Station ◽  
Initial Stage ◽  
Household Members ◽  
Community Based Design

This study confirms that lack of space due to high population density restricts household members and the barangay to comply with the existing law regarding composting. With these, community involvement in the design stage of compost bin as initial stage was done accordingly. The participants were voluntarily interviewed and were given questionnaires, which was endorsed and approved by barangay committee.

scholarly journals Population Density or Populations Size. Which Factor Determines Urban Traffic Congestion?

2021 ◽  
Vol 13 (8) ◽  
pp. 4280
Author(s):  
Yu Sang Chang ◽  
Sung Jun Jo ◽  
Yoo-Taek Lee ◽  
Yoonji Lee
Keyword(s):  
Population Density ◽  
Population Size ◽  
Traffic Congestion ◽  
Critical Role ◽  
Small Population ◽  
High Density ◽  
Urban Traffic ◽  
Contradictory Result ◽  
Low Density

A large number of articles have documented that as population density of cities increases, car use declines and public transit use rises. These articles had a significant impact of promoting high-density compact urban development to mitigate traffic congestion. Another approach followed by other researchers used the urban scaling model to indicate that traffic congestion increases as population size of cities increases, thus generating a possible contradictory result. Therefore, this study examines the role of both density and population size on traffic congestion in 164 global cities by the use of Stochastic Impacts by Regression on Population, Affluence and Technology model. We divide 164 cities into the two subgroups of 66 low density cities and 98 high density cities for analysis. The findings from the subgroups analysis indicated a clear-cut difference on the critical role of density in low-density cities and the exclusive role of population size in high-density cities. Furthermore, using threshold regression model, 164 cities are divided into the two regions of large and small population cities to determine population scale advantage of traffic congestion. Our findings highlight the importance of including analysis of subgroups based on density and/or population size in future studies of traffic congestion.

scholarly journals Effect of school reopening on SARS-CoV-2 incidence in a low-prevalence region: Prospective SARS-CoV-2 testing in healthcare workers with primary school-attending children versus without children living at home

2021 ◽  
pp. 175717742110124
Author(s):  
Melvin Frie ◽  
Lisa M Havinga ◽  
Janneke Wiersema-Buist ◽  
Charlotte G Veldman ◽  
Marjan JT de Vries ◽  
...  
Keyword(s):  
Cohort Study ◽  
Population Density ◽  
Severe Acute Respiratory Syndrome ◽  
Primary School ◽  
Primary Schools ◽  
Healthcare Workers ◽  
Regional Strategies ◽  
Low Prevalence ◽  
At Home

Coronavirus disease 2019 (COVID-19) often presents asymptomatically or milder in children compared to adults. The role of young children in the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) remains largely unknown. In the Netherlands, the first action of loosening the partial lockdown that had been implemented to reduce SARS-CoV-2 transmission was the reopening of primary schools on 1 May 2020. We subsequently conducted a prospective cohort study among healthcare workers (HCWs) with primary school-attending children versus HCWs without children living at home. We tested each HCW three times for SARS-CoV-2 from May 20 to June 15 2020 at 1-week intervals. In total, 832 nasopharyngeal swabs were taken from 283 HCWs with primary school-attending children living at home and 864 nasopharyngeal swabs from 285 HCWs without children living at home. All nasopharyngeal swabs tested negative for SARS-CoV-2. In our region with a low population density and low SARS-CoV-2 prevalence, reopening of primary schools did not lead to an increase in infections. The results of this study may serve as an example for the implementation of regional strategies to reduce SARS-CoV-2 transmission in countries with large variations in both population density and SARS-CoV-2 prevalence.

Parasite infection and host dynamics in a naturally fluctuating rodent population

2012 ◽  
Vol 90 (9) ◽  
pp. 1149-1160 ◽  
Author(s):  
J.C. Winternitz ◽  
M.J. Yabsley ◽  
S.M. Altizer
Keyword(s):  
Population Density ◽  
Experimental Studies ◽  
Host Density ◽  
Positive Association ◽  
Population Cycles ◽  
Host Population ◽  
Reproductive Status ◽  
Vole Cycles ◽  
Host Infection ◽  
The Impact

Parasites can both influence and be affected by host population dynamics, and a growing number of case studies support a role for parasites in causing or amplifying host population cycles. In this study, we examined individual and population predictors of gastrointestinal parasitism on wild cyclic montane voles ( Microtus montanus (Peale, 1848)) to determine if evidence was consistent with theory implicating parasites in population cycles. We sampled three sites in central Colorado for the duration of a multiannual cycle and recorded the prevalence and intensity of directly transmitted Eimeria Schneider, 1875 and indirectly transmitted cestodes from a total of 267 voles. We found significant associations between host infection status, individual traits (sex, age, and reproductive status) and population variables (site, trapping period, and population density), including a positive association between host density and cestode prevalence, and a negative association between host density and Eimeria prevalence. Both cestode and Eimeria intensity correlated positively with host age, reproductive status, and population density, but neither parasite was associated with poorer host condition. Our findings suggest that parasites are common in this natural host, but determining their potential to influence montane vole cycles requires future experimental studies and long-term monitoring to determine the fitness consequences of infection and the impact of parasite removal on host dynamics.

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