Population Cycles Causes and Analysis

2002 ◽  
Author(s):  
Alan A. Berryman
Keyword(s):  
Disease Transmission ◽  
Climatic Factors ◽  
Population Cycles ◽  
Physical Factor ◽  
Sunspot Activity ◽  
Nutrient Deficiencies ◽  
Plant Matter ◽  
Animal Populations ◽  
Predator Prey Models ◽  
Pathogen Populations

Ever since Elton’s classic book Voles, Mice and Lemmings (Elton 1942), understanding and explaining the causes of regular multiannual cycles in animal populations has been a central issue in ecology. Many hypotheses have been erected and incessantly argued about, but no clear picture has emerged. Below I briefly sketch the major hypotheses without any attempt to be complete or to comment on their relative merits or demerits. Detailed reviews and discussion can be found in Keith (1963), Krebs and Myers (1974), Finerty (1980), Myers (1988), Royama (1992), and Stenseth (1999). (H1) Physical effects (e.g., Elton 1924, Bodenheimer 1938). Perhaps the most obvious hypothesis is that cycles in animal populations reflect the response of birth and death rates to an external physical factor that is itself cyclic. Two of the more specific physical hypotheses involve periodic climatic factors and sunspot activity. (H2) Predator effects. Lotka (1924) and Volterra (1926) demonstrated that cyclic dynamics are inherent in simple predator-prey models, leading to the hypothesis that regular cycles can result from interactions between predator and prey populations. (H3) Pathogen effects. Anderson and May (1980) showed that, under certain conditions, simple models of infectious disease transmission can generate cycles in host and pathogen populations. This is similar to H2 with the pathogen as a predator. (H4) Plant effects. Several hypotheses have been proposed for the possible role of plants in generating population cycles of herbivores. One is a generalization of H2 in which the plant is considered the prey and the herbivore the predator (Elton 1924, Pitelka 1957). Another involves nutrient cycling: In this hypothesis, nutrient deficiencies are assumed to reduce the resistance of plants, resulting in larger herbivore populations, but nutrients released in feces and decaying animal and plant matter cycle back to the plants, increasing their vigor and resistance, and resulting in reduced herbivory (e.g., White 1974). Another hypothesis argues that herbivore feeding induces sustained chemical and/or physical changes in the plant (delayed induced resistance), which then reduce the reproduction and/or survival of future herbivore generations (Benz 1974, Haukioja and Hakala 1975).

Do Trophic Interactions Cause Population Cycles?

2002 ◽  
Author(s):  
Alan A. Berryman
Keyword(s):  
Time Series ◽  
Multivariate Time Series ◽  
Extended Period ◽  
Population Cycles ◽  
Web Architecture ◽  
Animal Populations ◽  
Spruce Stands ◽  
Long Time ◽  
Exhaustive Study

My motivation in editing this book has been to present as compelling and credible a story as possible. Although I am personally convinced of the soundness of our argument, that food web architecture plays a key role in the cyclic dynamics of many animal populations, I am not sure that others will be so convinced. In this final chapter, therefore, I exercise my prerogative as editor to have the last word, a final attempt to convince the skeptics and to answer the critics.Perhaps the most compelling case comes from the Mikael Münster-Swendsen monumental study of a needleminer infesting Danish spruce forests (chapter 2). Mikael is the only person I know of who has, almost single-handedly, and with considerable precision, measured all the variables suspected of affecting the dynamics of a particular population over an extended period of time (19 years) and in several different localities (seven isolated spruce stands). Others have longer time series from more places, but none has been so complete in terms of the number of variables measured. This exhaustive study enabled him to build a model of the complete needleminer life system, and use this model to home in on the factors responsible for the cyclical dynamics. However, the story would not have been complete without multivariate time series analysis, which led to the discovery of parasitoids as the cause of the key feedback process, density-related reduction in fecundity. The lesson from Münster-Swendsen's work is clear: If we want to understand population dynamics, we need long time series for all the variables likely to affect the dynamics of the subject population(s). In other words, we need to consistently monitor ecological systems over long periods of time and in many different locations. If there is a weakness in his study, it is the absence of the final definitive experiment. Such an experiment would be relatively easy and cheap to do (relative to those described in other chapters), because isolated spruce stands are common in Denmark and parasitoids emerge from the soil a week or two after the needleminer. Thus, parasitoids could easily be excluded by spraying the ground with an insecticide after needleminer emergence.

scholarly journals Long-term surveillance defines spatial and temporal patterns implicating Culex tarsalis as the primary vector of West Nile virus in Iowa, USA

2018 ◽  
Author(s):  
Brendan M. Dunphy ◽  
Kristofer B. Kovach ◽  
Ella J. Gehrke ◽  
Eleanor N. Field ◽  
Wayne A. Rowley ◽  
...  
Keyword(s):  
West Nile Virus ◽  
Disease Transmission ◽  
Climatic Factors ◽  
Strong Support ◽  
The United States ◽  
Culex Tarsalis ◽  
Mosquito Vectors ◽  
Spatial And Temporal Patterns ◽  
West Nile

AbstractWest Nile virus (WNV) has become the most epidemiologically important mosquito-borne disease in the United States, causing ∼50,000 cases since its introduction in 1999. Transmitted primarily by Culex species, WNV transmission requires the complex interplay between bird reservoirs and mosquito vectors, with human cases the result of epizootic spillover. To better understand the intrinsic factors that drive these interactions, we have compiled infection data from sentinel chickens, mosquito vectors, and human cases in Iowa over a 15 year period (2002-2016) to better understand the spatial and temporal components that drive WNV transmission. Supplementing these findings with mosquito abundance, distribution, and host preferences data, we provide strong support that Culex tarsalis is the most important vector of human WNV infections in the region. Finally, we identify underlying climatic factors (temperature and drought) that are associated with inter-annual trends in WNV intensity. Together, our analysis provides new insights into WNV infection patterns in multiple hosts and highlights the importance of long-term surveillance to understand the dynamics of mosquito-borne-disease transmission.

scholarly journals Cycles, stochasticity and density dependence in pink salmon population dynamics

2010 ◽  
Vol 278 (1714) ◽  
pp. 2060-2068 ◽  
Author(s):  
Martin Krkošek ◽  
Ray Hilborn ◽  
Randall M. Peterman ◽  
Thomas P. Quinn
Keyword(s):  
Density Dependence ◽  
Disease Transmission ◽  
Pink Salmon ◽  
The Other ◽  
Oncorhynchus Gorbuscha ◽  
Stochastic Perturbations ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Animal Populations ◽  
Dependent Mortality

Complex dynamics of animal populations often involve deterministic and stochastic components. A fascinating example is the variation in magnitude of 2-year cycles in abundances of pink salmon ( Oncorhynchus gorbuscha ) stocks along the North Pacific rim. Pink salmon have a 2-year anadromous and semelparous life cycle, resulting in odd- and even-year lineages that occupy the same habitats but are reproductively isolated in time. One lineage is often much more abundant than the other in a given river, and there are phase switches in dominance between odd- and even-year lines. In some regions, the weak line is absent and in others both lines are abundant. Our analysis of 33 stocks indicates that these patterns probably result from stochastic perturbations of damped oscillations owing to density-dependent mortality caused by interactions between lineages. Possible mechanisms are cannibalism, disease transmission, food depletion and habitat degradation by which one lineage affects the other, although no mechanism has been well-studied. Our results provide comprehensive empirical estimates of lagged density-dependent mortality in salmon populations and suggest that a combination of stochasticity and density dependence drives cyclical dynamics of pink salmon stocks.

scholarly journals Personality in the context of social networks

2010 ◽  
Vol 365 (1560) ◽  
pp. 4099-4106 ◽  
Author(s):  
J. Krause ◽  
R. James ◽  
D. P. Croft
Keyword(s):  
Fine Structure ◽  
Social Network ◽  
Social Network Analysis ◽  
Network Analysis ◽  
Disease Transmission ◽  
Dyadic Relationships ◽  
Network Position ◽  
Animal Populations ◽  
The Social ◽  
Interactive Strategies

There is great interest in environmental effects on the development and evolution of animal personality traits. An important component of an individual's environment is its social environment. However, few studies look beyond dyadic relationships and try to place the personality of individuals in the context of a social network. Social network analysis provides us with many new metrics to characterize the social fine-structure of populations and, therefore, with an opportunity to gain an understanding of the role that different personalities play in groups, communities and populations regarding information or disease transmission or in terms of cooperation and policing of social conflicts. The network position of an individual is largely a consequence of its interactive strategies. However, the network position can also shape an individual's experiences (especially in the case of juveniles) and therefore can influence the way in which it interacts with others in future. Finally, over evolutionary time, the social fine-structure of animal populations (as quantified by social network analysis) can have important consequences for the evolution of personalities—an approach that goes beyond the conventional game-theoretic analyses that assumed random mixing of individuals in populations.

scholarly journals Influence of Climatic Factors on Human Hantavirus Infections in Latin America and the Caribbean: A Systematic Review

Pathogens ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Kirk Osmond Douglas ◽  
Karl Payne ◽  
Gilberto Sabino-Santos ◽  
John Agard
Keyword(s):  
Climate Change ◽  
Infectious Disease ◽  
Systematic Review ◽  
Latin America ◽  
Infectious Diseases ◽  
Disease Transmission ◽  
Climatic Factors ◽  
Habitat Type ◽  
Inclusion Criteria ◽  
The Caribbean

Background: With the current climate change crisis and its influence on infectious disease transmission there is an increased desire to understand its impact on infectious diseases globally. Hantaviruses are found worldwide, causing infectious diseases such as haemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS)/hantavirus pulmonary syndrome (HPS) in tropical regions such as Latin America and the Caribbean (LAC). These regions are inherently vulnerable to climate change impacts, infectious disease outbreaks and natural disasters. Hantaviruses are zoonotic viruses present in multiple rodent hosts resident in Neotropical ecosystems within LAC and are involved in hantavirus transmission. Methods: We conducted a systematic review to assess the association of climatic factors with human hantavirus infections in the LAC region. Literature searches were conducted on MEDLINE and Web of Science databases for published studies according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) criteria. The inclusion criteria included at least eight human hantavirus cases, at least one climatic factor and study from > 1 LAC geographical location. Results: In total, 383 papers were identified within the search criteria, but 13 studies met the inclusion criteria ranging from Brazil, Chile, Argentina, Bolivia and Panama in Latin America and a single study from Barbados in the Caribbean. Multiple mathematical models were utilized in the selected studies with varying power to generate robust risk and case estimates of human hantavirus infections linked to climatic factors. Strong evidence of hantavirus disease association with precipitation and habitat type factors were observed, but mixed evidence was observed for temperature and humidity. Conclusions: The interaction of climate and hantavirus diseases in LAC is likely complex due to the unknown identity of all vertebrate host reservoirs, circulation of multiple hantavirus strains, agricultural practices, climatic changes and challenged public health systems. There is an increasing need for more detailed systematic research on the influence of climate and other co-related social, abiotic, and biotic factors on infectious diseases in LAC to understand the complexity of vector-borne disease transmission in the Neotropics.

scholarly journals Genetic Diversity and Population Structure of the Asian Tiger Mosquito (Aedes albopictus) in Vietnam: Evidence for Genetic Differentiation by Climate Region

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1579
Author(s):  
Cuong Van Duong ◽  
Ji Hyoun Kang ◽  
Vinh Van Nguyen ◽  
Yeon Jae Bae
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Aedes Albopictus ◽  
Disease Transmission ◽  
Climatic Factors ◽  
Control Strategies ◽  
Geographic Distance ◽  
Coi Gene ◽  
Tropical Regions ◽  
Climatic Regions

Aedes albopictus is a native mosquito to Southeast Asia with a high potential for disease transmission. Understanding how Ae. albopictus populations that develop in the species’ native range is useful for planning future control strategies and for identifying the sources of invasive ranges. The present study aims to investigate the genetic diversity and population structure of Ae. albopictus across various climatic regions of Vietnam. We analyzed mitochondrial cytochrome oxidase I (COI) gene sequences from specimens collected from 16 localities, and we used distance-based redundancy analysis to evaluate the amount of variation in the genetic distance that could be explained by both geographic distance and climatic factors. High levels of genetic polymorphism were detected, and the haplotypes were similar to those sequences from both temperate and tropical regions worldwide. Of note, these haplotype groups were geographically distributed, resulting in a distinct population structure in which northeastern populations and the remaining populations were genetically differentiated. Notably, genetic variation among the Ae. albopictus populations was driven primarily by climatic factors (64.55%) and to a lesser extent was also influenced by geographic distance (33.73%). These findings fill important gaps in the current understanding of the population genetics of Ae. albopictus in Vietnam, especially with respect to providing data to track the origin of the invaded regions worldwide.

scholarly journals Exploring the Potential of Interferon Gamma Gene as Major Immune Responder for Bovine Tuberculosis in River Buffalo

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Maryam Javed ◽  
Syed Ahmed Raza ◽  
Asif Nadeem ◽  
Muhammad Muddassir Ali ◽  
Wasim Shehzad ◽  
...  
Keyword(s):  
Interferon Gamma ◽  
Disease Transmission ◽  
Bovine Tuberculosis ◽  
Gene Diversity ◽  
Genomic Structure ◽  
Natural Immunity ◽  
River Buffalo ◽  
Nucleotide Polymorphisms ◽  
Coding Region ◽  
Animal Populations

Bovine tuberculosis (bTB) is a widespread zoonotic infection targeting the livestock sector, especially in developing countries, and posing a risk to humans and animal populations. Its recent prevalence in river buffaloes has been estimated as higher as 33.7%. In emergent countries like Pakistan, there is likeliness of human-livestock interfaces extensively and lacking of effective preventive measures that illustrate the risk of spreading the infection at a remarkable rate. The river buffalo (Bubalus bubalis) is an upkeep host of Mycobacterium bovis and is responsible for disease transmission among buffaloes and other livestock species. In this study, potential molecular biomarkers in the Interferon-gamma gene (IFNg) were identified after genomic screening of river buffaloes. Unique genomic loci in river buffalo proved the novelty of the genomic structure of this phenomenal animal but also highlighted its significance in natural immunity against the Mycobacterium. A total of eight single nucleotide polymorphisms were identified in the coding region of IFNg. The SNPs in the exonic region were all transitions, i.e., the conversion of purines to purines. These SNPs were analyzed for Hardy Weinberg Equilibrium, chi2 test, gene diversity, and protein structural conformation. Pathway analysis in tuberculosis revealed that IFNg inhibits the antigen-presenting cells (APC) through JAK and STAT pathways. Network analysis of IFNg proteins in both species showed strong associations among the immunity-related proteins (interleukins, tissue necrosis factors) and receptors of interferons. The identified polymorphic sites might be novel-potentiated markers for the selection of animals with superior immune response against bTB and can be exploited as promising genomic sites for breeding the resistant animal herds to combat Mycobacterium infection in a long run.

scholarly journals Solasodine and Gosipol Effectivity as a Male Contraception Inhibit LH Expression and Spermatogenesis in Rat

2019 ◽  
Vol 1 (2) ◽  
pp. 51-59
Author(s):  
Desi Wulansari ◽  
◽  
Yudit Oktanella ◽  
Viski Fitri Hendrawan ◽  
Galuh Chandra Agustina ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Population Control ◽  
Sperm Concentration ◽  
Wild Animal ◽  
Solanum Torvum ◽  
Ceiba Pentandra ◽  
Animal Populations ◽  
Canine Population ◽  
Result Show ◽  
One Way Anova

Rabies related to increasing canine population in Bali. Uncontrolled wild animal populations caused disease transmission from animal to human. Various attempt at population control are carried out such as the use of natural contraception. Some compounds are known to have potential as antifertility are solasodine and gosipol. Solasodine is known have an antifertility affect. Gosipol, fenolic compound in Ceiba pentandra, inhibits spermatogenesis, reduce sperm concentration, motility and viability. This research aims to compare effectiveness of terong cepoka and Ceiba pentandra as antifertility. This research was conducted at Mei-November 2018. Eight-teen rats were used in this study and divided into three groups: control, P1 extract Solanum torvum 1g/kg BW and P2 extract Ceiba pentandra 0,1g/kg BW PO. Rats were treated with extract for 10 days and euthanazed at day 11. Testis were collected for histopathology using HE staining to observe spermatogenesis and using immunohistochemistry to observe LH expression. The result are analyzed using one way ANOVA P<0.05. the result show that extract solanum torvum 1g/kg BW and ceiba pentandra 0,1g/kgBW cannot reduce spermatogenesis and LH expression. This study used crude extract which still consist any other compound like antioxidant. Future study we need use isolated and pure solasodine and gosipol.

scholarly journals Climatic Factors Reproductive Success and Population Dynamics in the Montane Vole, Microtus montanus

1998 ◽  
Vol 22 ◽  
pp. 28-30
Author(s):  
Aelita Pinter
Keyword(s):  
Environmental Variables ◽  
Climatic Factors ◽  
Population Cycles ◽  
Small Rodents ◽  
Term Study ◽  
Red Grouse ◽  
Microtus Montanus ◽  
Long Term Study ◽  
Lagopus Lagopus Scoticus

Multiannual fluctuations in population density ("cycles") of small rodents have been known since antiquity (Elton 1942). Numerous hypotheses have been proposed to explain this phenomenon (for reviews see Finerty 1980, Taitt and Krebs 1985). However, none of these hypotheses, alone or in combination, has been able to explain the causality of cycles, although recently removal of parasites was shown to prevent population cycles in the red grouse, Lagopus lagopus scoticus (Hudson et al. 1998). The objectives of this long-term study are to determine whether environmental variables, possibly acting through reproductive responses, contribute to the multiannual fluctuations of the montane vole, Microtus montanus.

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