Biotics: Competition, Herbivory, Predation, Parasitism and Symbiosis

2017 ◽  
Author(s):  
Christer Brönmark ◽  
Lars-Anders Hansson
Keyword(s):  
Population Dynamics ◽  
Ecosystem Function ◽  
Theoretical Basis ◽  
Abiotic Factors ◽  
Biological Interactions ◽  
Natural Systems ◽  
The Many

If biological interactions, such as competition and predation, have any effect on population dynamics, or if abiotic factors alone determine which organisms, how many of them do we see in a specific ecosystem, was for long a controversial question. This chapter aims at providing the basis for the understanding of biological interactions, as well as showing ample examples of how important those interactions are in shaping both population dynamics and ecosystem function of natural systems. In addition to the many examples, the reader is introduced to the history and the theoretical basis for biological interactions.

scholarly journals Detecting alternative attractors in ecosystem dynamics

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Torbjörn Säterberg ◽  
Kevin McCann
Keyword(s):  
Population Dynamics ◽  
Time Series Data ◽  
Abiotic Factors ◽  
Natural Populations ◽  
Ecosystem Dynamics ◽  
Series Data ◽  
Natural Systems ◽  
Experimental Systems ◽  
Dynamical Behaviors ◽  
Natural Time

AbstractDynamical systems theory suggests that ecosystems may exhibit alternative dynamical attractors. Such alternative attractors, as for example equilibria and cycles, have been found in the dynamics of experimental systems. Yet, for natural systems, where multiple biotic and abiotic factors simultaneously affect population dynamics, it is more challenging to distinguish alternative dynamical behaviors. Although recent research exemplifies that some natural systems can exhibit alternative states, a robust methodology for testing whether these constitute distinct dynamical attractors is currently lacking. Here, using attractor reconstruction techniques we develop such a test. Applications of the methodology to simulated, experimental and natural time series data, reveal that alternative dynamical behaviors are hard to distinguish if population dynamics are governed by purely stochastic processes. However, if population dynamics are brought about also by mechanisms internal to the system, alternative attractors can readily be detected. Since many natural populations display evidence of such internally driven dynamics, our approach offers a method for empirically testing whether ecosystems exhibit alternative dynamical attractors.

What does the concept of affordances afford?

2021 ◽  
pp. 105971232098268
Author(s):  
Rob Withagen ◽  
Alan Costall
Keyword(s):  
Lived Experience ◽  
Theoretical Basis ◽  
Scientific Work ◽  
Ecological Approach ◽  
Design Practices ◽  
The Many ◽  
Architecture And Design ◽  
Functional Concept

Gibson once suggested that his ecological approach could provide architecture and design with a new theoretical basis. Erik Rietveld takes up this suggestion—the concept of affordances figures prominently not only in his philosophical and scientific work but also in the design practices he is engaged in. However, as Gibson introduced affordances as a functional concept, it seems ill-suited to capture the many dimensions of our lived experience of the (manufactured) environment. Can the concept of affordances also take on the expressive and aesthetic qualities of artifacts and buildings?

scholarly journals Parasitism of Aedes albopictus by Ascogregarina taiwanensis lowers its competitive ability against Aedes triseriatus

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Emma Stump ◽  
Lauren M. Childs ◽  
Melody Walker
Keyword(s):  
Population Dynamics ◽  
Competitive Advantage ◽  
Aedes Albopictus ◽  
Abiotic Factors ◽  
Mosquito Species ◽  
Disease Spread ◽  
Aedes Triseriatus ◽  
La Crosse Virus ◽  
The Impact ◽  
Ascogregarina Taiwanensis

Abstract Background Mosquitoes are vectors for diseases such as dengue, malaria and La Crosse virus that significantly impact the human population. When multiple mosquito species are present, the competition between species may alter population dynamics as well as disease spread. Two mosquito species, Aedes albopictus and Aedes triseriatus, both inhabit areas where La Crosse virus is found. Infection of Aedes albopictus by the parasite Ascogregarina taiwanensis and Aedes triseriatus by the parasite Ascogregarina barretti can decrease a mosquito’s fitness, respectively. In particular, the decrease in fitness of Aedes albopictus occurs through the impact of Ascogregarina taiwanensis on female fecundity, larval development rate, and larval mortality and may impact its initial competitive advantage over Aedes triseriatus during invasion. Methods We examine the effects of parasitism of gregarine parasites on Aedes albopictus and triseriatus population dynamics and competition with a focus on when Aedes albopictus is new to an area. We build a compartmental model including competition between Aedes albopictus and triseriatus while under parasitism of the gregarine parasites. Using parameters based on the literature, we simulate the dynamics and analyze the equilibrium population proportion of the two species. We consider the presence of both parasites and potential dilution effects. Results We show that increased levels of parasitism in Aedes albopictus will decrease the initial competitive advantage of the species over Aedes triseriatus and increase the survivorship of Aedes triseriatus. We find Aedes albopictus is better able to invade when there is more extreme parasitism of Aedes triseriatus. Furthermore, although the transient dynamics differ, dilution of the parasite density through uptake by both species does not alter the equilibrium population sizes of either species. Conclusions Mosquito population dynamics are affected by many factors, such as abiotic factors (e.g. temperature and humidity) and competition between mosquito species. This is especially true when multiple mosquito species are vying to live in the same area. Knowledge of how population dynamics are affected by gregarine parasites among competing species can inform future mosquito control efforts and help prevent the spread of vector-borne disease.

scholarly journals Population Dynamics of Amrasca biguttula biguttula on Bt and Non Bt Cotton and Its Correlation with Abiotic Factors

2018 ◽  
Vol 7 (09) ◽  
pp. 2927-2934
Author(s):  
Praveen Kumar ◽  
S.P. Yadav ◽  
Krishna Rolania ◽  
Sunita Yadav ◽  
Surender Singh ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Abiotic Factors ◽  
Bt Cotton ◽  
Amrasca Biguttula Biguttula

scholarly journals Optimal transcriptional regulation of cellular responses to sudden environmental shifts

2020 ◽  
Author(s):  
Daniel Schultz ◽  
Lev S. Tsimring
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Cell Response ◽  
Cellular Responses ◽  
Natural Systems ◽  
Selective Pressures ◽  
Regulatory Strategies ◽  
Regulatory Strategy ◽  
A Cell ◽  
The Many

ABSTRACTCellular responses to sudden changes in their environment require prompt expression of the correct levels of the appropriate enzymes. These enzymes are typically regulated by transcription factors that sense the presence of inducers and control gene expression for the duration of the response. The specific choice of regulatory strategy depends on the characteristics of each cell response, with the pattern of gene expression dictated by parameters such as the affinity of the transcription factor to its binding sites and the strength of the promoters it regulates. Although much is known about how gene regulation determines the dynamics of cell responses, we still lack a framework to understand how the many different regulatory strategies evolved in natural systems relate to the constraints imposed by the selective pressures acting in each particular case. Here, we analyze a dynamical model of a cell response where expression of a transcriptionally repressed enzyme is induced by a sudden exposure to its substrate. We identify strategies of gene regulation that optimize the response for different types of selective pressures, which we define as a set of costs associated with substrate, enzyme and repressor intracellular concentrations during the response. We find that regulated responses happen within a defined region in the parameter space. While responses to costly (toxic) substrates favor the usage of strongly self-regulated repressors, responses where expression of enzyme is more costly than its substrate favor the usage of constitutively expressed repressors. There is only a very narrow range of selective pressures that would favor weakly self-regulated repressors. This framework can be used to infer which costs and benefits are most critical in the evolution of natural examples of cellular responses, and to predict how a response can optimize its regulation when transported to a new environment with different demands.

scholarly journals Population dynamics of exotic rugose spiralling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) on coconut as influenced by weather factors and natural enemies

2020 ◽  
pp. 120-125
Author(s):  
K. Elango ◽  
S. Jeyarajan Nelson
Keyword(s):  
Population Dynamics ◽  
Negative Correlation ◽  
Natural Enemies ◽  
Tamil Nadu ◽  
Abiotic Factors ◽  
Climatic Conditions ◽  
Weekly Interval ◽  
Maximum Temperature ◽  
Weather Factors ◽  
Extent Of Damage

The rugose spiralling whitefly, Aleurodicus rugioperculatus Martin is a new exotic pest occurring in several crops including coconut since 2016 in India. Due to variation in the agro-climatic conditions of different regions, arthropods show varying trends in their incidence also in nature and extent of damage to the crop. Besides, abiotic factors also play a key role in determining the incidence and dominance of a particular pest and their natural enemies in a crop ecosystem. The population dynamics of new exotic whitefly species, A. rugioperculatus and their associated natural enemies was assessed on five-year-old Chowghat Orange Dwarf coconut trees at Coconut Farm of Tamil Nadu Agricultural University. The study indicated that RSW was found throughout the year on coconut and the observation recorded on weekly interval basis shows that A. rugioperculatus population escalated from the first week of July 2018 (130.8 nymphs/leaf/frond) reaching the maximum during the first week of October (161.0 nymphs/leaf/frond) which subsequently dwindled to a minimum during April. The parasitisation by E. guadeloupae on RSW ranged from 31.60 percent in Aug. 2018 to 57.60 percent in December 2018. The association of biotic and abiotic factors with A. rugioperculatus population showed a negative correlation with E. guadeloupae and C. montrouzieri. There was a significant positive correlation between maximum temperature and minimum temperature as well as relative humidity. However, rainfall showed a negative correlation with A. rugioperculatus population.

Conclusion and Outlook

2017 ◽  
Author(s):  
Matteo Cervellati ◽  
Uwe Sunde
Keyword(s):  
Economic Development ◽  
Population Dynamics ◽  
Demographic Transition ◽  
Turning Point ◽  
Transition Process ◽  
Low Fertility ◽  
Interdisciplinary Work ◽  
Space And Time ◽  
Long Run ◽  
The Many

This concluding chapter discusses this book's origins in the argument that the demographic transition is a key turning point for long-run development, not only in terms of a change in the regime of population dynamics toward low fertility and mortality, but also in the process of long-run economic development. The observed similarities in the transition process across space and time suggest that a better understanding of the reasons for such occurrences as the delay in the development of some countries might provide insights that are relevant beyond academic interest. The chapter argues that more interdisciplinary work between economists, demographers, and historians are needed to address the many facets that are covered only in passing, or not at all.

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