scholarly journals Testing predator - prey theory by studying fluctuating populations of small mammals.

1995 ◽  
Vol 22 (1) ◽  
pp. 89 ◽  
Author(s):  
S. Boutin
Keyword(s):  
Population Dynamics ◽  
Small Mammals ◽  
Limit Cycles ◽  
Functional Responses ◽  
Predator Satiation ◽  
Linear Type ◽  
Small Component ◽  
Wide Range ◽  
Fluctuating Populations

Fluctuating populations of small mammals provide an excellent opportunity to study the functional and numerical responses of predators because of the wide range in prey density that occurs. I reinterpret data from six studies that have examined the role of predation in the population dynamics of voles in California, southern Sweden and western Finland, of snowshoe hares in northern Canada, and of house mice and rabbits in Australia. Most studies have measured functional responses by relying on changes in diet as reflected by scat or stomach contents. These methods are probably biased toward showing predator satiation. Contrary to previous conclusions I find that there is little evidence for non-linear (Type 111) functional-response curves or predator satiation at high prey densities. Recent studies indicate that the functional and numerical responses of predators can be rapid and strong enough to initiate cyclic declines, dampen fluctuations, or even cause stable numbers. The exception to this appears to be the irruptions of mice and rabbits in Australia. I propose a general explanation for the role of predation whereby the effect of predation is largely dependent on the entire prey community. When potentially cyclic prey are a small component of the overall prey biomass, generalist predators are able to prevent fluctuations by strong functional or numerical responses. As the prey community becomes dominated by a few species that fluctuate, limit cycles predominate. Limit cycles turn into irruptive population dynamics when seasonal prey reproduction is eliminated because of extended periods of vegetation growth (vegetation flushes following drought). In the future we must test assumptions underlying the way we study predation by telemetric monitoring of prey mortality and by experimentally manipulating predation.

scholarly journals Modular prophage interactions driven by capsule serotype select for capsule loss under phage predation

2019 ◽  
Author(s):  
Jorge A. Moura de Sousa ◽  
Amandine Buffet ◽  
Matthieu Haudiquet ◽  
Eduardo P.C. Rocha ◽  
Olaya Rendueles
Keyword(s):  
Population Dynamics ◽  
Gene Flow ◽  
Klebsiella Pneumoniae ◽  
Species Complex ◽  
Interaction Network ◽  
Lytic Cycle ◽  
Nosocomial Pathogens ◽  
Wide Range ◽  
Key Factor

ABSTRACTKlebsiella species are able to colonize a wide range of environments and include worrisome nosocomial pathogens. Here, we sought to determine the abundance and infectivity of prophages of Klebsiella to understand how the interactions between induced prophages and bacteria affect population dynamics and evolution. We identified many prophages in the species, placing these taxa among the top 5% of the most polylysogenic bacteria. We selected 35 representative strains of the Klebsiella pneumoniae species complex to establish a network of induced phage-bacteria interactions. This revealed that many prophages are able to enter the lytic cycle, and subsequently kill or lysogenize closely-related Klebsiella strains. Although 60% of the tested strains could produce phages that infect at least one other strain, the interaction network of all pairwise cross-infections is very sparse and mostly organized in modules corresponding to the strains’ capsule serotypes. Accordingly, capsule mutants remain uninfected showing that the capsule is a key factor for successful infections. Surprisingly, experiments in which bacteria are predated by their own prophages result in accelerated loss of the capsule. Our results show that phage infectiousness defines interaction modules between small subsets of phages and bacteria in function of capsule serotype. This limits the role of prophages as competitive weapons because they can infect very few strains of the species complex. This should also restrict phage-driven gene flow across the species. Finally, the accelerated loss of the capsule in bacteria being predated by their own phages, suggests that phages drive serotype switch in nature.

The role of dispersal in the population dynamics of snowshoe hares

1985 ◽  
Vol 63 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Stan Boutin ◽  
B. S. Gilbert ◽  
Charles J. Krebs ◽  
A. R. E. Sinclair ◽  
J. N. M. Smith
Keyword(s):  
Population Dynamics ◽  
Small Mammals ◽  
Lepus Americanus ◽  
Population Increase ◽  
Dispersal Rate ◽  
Population Densities ◽  
Control Grid ◽  
Snowshoe Hares ◽  
Kluane Lake

We monitored dispersal of snowshoe hares (Lepus americanus) at Kluane Lake, Yukon, during a population increase, peak, and decline. Dispersal was measured by recording the number of immigrants to a removal grid and by tracking radiocollared individuals. The observed decline was not due to dispersal, as a maximum of 28% of all losses of radiocollared animals was due to dispersal. Dispersal rate (as measured by number of immigrants to the removal grid per individual on the control grid) was negatively correlated (−0.51, P < 0.01) with the rate of population increase. Highest dispersal rates occurred in the winters when hare populations were at peak and early decline densities. Dispersers at this time were lighter in weight than residents. We discuss our results in light of current hypotheses attempting to explain dispersal in cyclic small mammals and conclude that our results are consistent with the hypothesis that food shortage is responsible for increased rates of dispersal at peak population densities Comparison of dispersal, as monitored by radiotelemetry, versus immigration to a removal grid, suggests that removal grids overestimate dispersal, particularly at high densities when removal grids may attract animals because food supplies are relatively favorable there.

Zoonoses as factor of evolution, population dynamics, and speciation

2021 ◽  
pp. 153-172
Author(s):  
Igor Evstafiev ◽  
Igor Zagorodniuk
Keyword(s):  
Population Dynamics ◽  
Small Mammals ◽  
Population Diversity ◽  
Crimean Peninsula ◽  
Species Ranges ◽  
Animal Populations ◽  
Tick Borne Encephalitis ◽  
Evolutionary Changes ◽  
Population Numbers

The role of zoonoses in changes of animal populations and communities is considered. The analysis was carried out using examples of population dynamics of small mammals distributed in the Crimean Peninsula, under the influence of the main zoonoses common for this territory, in particular tularaemia, leptospirosis, Marseille fever, viral tick-borne encephalitis, Ixodes tick-borne borreliosis, Crimea-Congo fever, KU fever, HFRS, and many others. Such data were analysed according to databases on the state of small-mammal populations and zoonoses common in these populations, obtained by original studies over the past 40 years. The role of zoonoses as factors of evolutionary changes in populations of small mammals is considered, in particular as a factor of mortality leading to significant reductions in population numbers and fragmentation of species ranges, as well as factors determining co-evolution of pathogens, vectors (arthropods), and small-mammals as hosts. Both groups of factors lead to the formation of population diversity due to changes in character variability and the formation of new characters associated with adaptations to zoonoses.

scholarly journals Experimental duration and predator satiation levels systematically affect functional response parameters

2017 ◽  
Author(s):  
Yuanheng Li ◽  
Björn C. Rall ◽  
Gregor Kalinkat
Keyword(s):  
Food Web ◽  
Functional Response ◽  
Large Data ◽  
Handling Time ◽  
Set Covering ◽  
Parameter Estimates ◽  
Functional Responses ◽  
Predator Satiation ◽  
Data Set ◽  
Wide Range

AbstractEmpirical feeding studies where density-dependent consumption rates are fitted to functional response models are often used to parametrize the interaction strengths in models of population or food-web dynamics. However, the relationship between functional response parameter estimates from short-term feeding studies and real-world, long-term, trophic interaction strengths remains largely untested. In a critical first step to address this void, we tested for systematic effects of experimental duration and predator satiation on the estimation of functional response parameters, namely attack rate and handling time. Analyzing a large data set covering a wide range of predator taxonomies and body sizes we show that attack rates decrease with increasing experimental duration, and that handling times of starved predators are consistently shorter than those of satiated predators. Therefore, both the experimental duration and the predator satiation level have a strong and systematic impact on the predictions of population dynamics and food-web stability. Our study highlights potential pitfalls at the intersection of empirical and theoretical applications of functional responses. We conclude our study with some practical suggestions how these implications should be addressed in the future to improve predictive abilities and realism in models of predator-prey interactions.

scholarly journals Modular prophage interactions driven by capsule serotype select for capsule loss under phage predation

2020 ◽  
Vol 14 (12) ◽  
pp. 2980-2996 ◽  
Author(s):  
Jorge A. M. de Sousa ◽  
Amandine Buffet ◽  
Matthieu Haudiquet ◽  
Eduardo P. C. Rocha ◽  
Olaya Rendueles
Keyword(s):  
Population Dynamics ◽  
Gene Flow ◽  
Klebsiella Pneumoniae ◽  
Species Complex ◽  
Interaction Network ◽  
Lytic Cycle ◽  
Nosocomial Pathogens ◽  
Wide Range ◽  
Key Factor

Abstract Klebsiella species are able to colonize a wide range of environments and include worrisome nosocomial pathogens. Here, we sought to determine the abundance and infectivity of prophages of Klebsiella to understand how the interactions between induced prophages and bacteria affect population dynamics and evolution. We identified many prophages in the species, placing these taxa among the top 5% of the most polylysogenic bacteria. We selected 35 representative strains of the Klebsiella pneumoniae species complex to establish a network of induced phage–bacteria interactions. This revealed that many prophages are able to enter the lytic cycle, and subsequently kill or lysogenize closely related Klebsiella strains. Although 60% of the tested strains could produce phages that infect at least one other strain, the interaction network of all pairwise cross-infections is very sparse and mostly organized in modules corresponding to the strains’ capsule serotypes. Accordingly, capsule mutants remain uninfected showing that the capsule is a key factor for successful infections. Surprisingly, experiments in which bacteria are predated by their own prophages result in accelerated loss of the capsule. Our results show that phage infectiousness defines interaction modules between small subsets of phages and bacteria in function of capsule serotype. This limits the role of prophages as competitive weapons because they can infect very few strains of the species complex. This should also restrict phage-driven gene flow across the species. Finally, the accelerated loss of the capsule in bacteria being predated by their own phages, suggests that phages drive serotype switch in nature.

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

Introduction: Emotion, History and the Arts

2018 ◽  
Vol 7 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Erin Sullivan ◽  
Marie Louise Herzfeld-Schild
Keyword(s):  
Historical Change ◽  
Carson Mccullers ◽  
Emotional Life ◽  
Review Section ◽  
The Arts ◽  
Wide Range ◽  
War Correspondents ◽  
History Of ◽  
Johan Huizinga

This introduction surveys the rise of the history of emotions as a field and the role of the arts in such developments. Reflecting on the foundational role of the arts in the early emotion-oriented histories of Johan Huizinga and Jacob Burkhardt, as well as the concerns about methodological impressionism that have sometimes arisen in response to such studies, the introduction considers how intensive engagements with the arts can open up new insights into past emotions while still being historically and theoretically rigorous. Drawing on a wide range of emotionally charged art works from different times and places—including the novels of Carson McCullers and Harriet Beecher-Stowe, the private poetry of neo-Confucian Chinese civil servants, the photojournalism of twentieth-century war correspondents, and music from Igor Stravinsky to the Beatles—the introduction proposes five ways in which art in all its forms contributes to emotional life and consequently to emotional histories: first, by incubating deep emotional experiences that contribute to formations of identity; second, by acting as a place for the expression of private or deviant emotions; third, by functioning as a barometer of wider cultural and attitudinal change; fourth, by serving as an engine of momentous historical change; and fifth, by working as a tool for emotional connection across communities, both within specific time periods but also across them. The introduction finishes by outlining how the special issue's five articles and review section address each of these categories, while also illustrating new methodological possibilities for the field.

Short Films from a Small Nation

2018 ◽  
Author(s):  
C. Claire Thomson
Keyword(s):  
Public Information ◽  
Industrial Process ◽  
Actor Network Theory ◽  
Documentary Films ◽  
Wide Range ◽  
Short Films ◽  
Post War ◽  
The 1960S ◽  
Art And Architecture

The first book-length study in English of a national corpus of state-sponsored informational film, this book traces how Danish shorts on topics including social welfare, industry, art and architecture were commissioned, funded, produced and reviewed from the inter-war period to the 1960s. For three decades, state-sponsored short filmmaking educated Danish citizens, promoted Denmark to the world, and shaped the careers of renowned directors like Carl Th. Dreyer. Examining the life cycle of a representative selection of films, and discussing their preservation and mediation in the digital age, this book presents a detailed case study of how informational cinema is shaped by, and indeed shapes, its cultural, political and technological contexts.The book combines close textual analysis of a broad range of films with detailed accounts of their commissioning, production, distribution and reception in Denmark and abroad, drawing on Actor-Network Theory to emphasise the role of a wide range of entities in these processes. It considers a broad range of genres and sub-genres, including industrial process films, public information films, art films, the city symphony, the essay film, and many more. It also maps international networks of informational and documentary films in the post-war period, and explores the role of informational film in Danish cultural and political history.

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