scholarly journals Epidemiological dynamics of viral infection in a marine picoeukaryote

2021 ◽  
Author(s):  
Luisa Listmann ◽  
Sarah Heath ◽  
Pedro F. Vale ◽  
C. Elisa Schaum ◽  
Sinead Collins
Keyword(s):  
Population Dynamics ◽  
Laboratory Experiments ◽  
Natural Populations ◽  
Epidemiological Models ◽  
Laboratory Findings ◽  
Serial Transfer ◽  
Natural Systems ◽  
Ostreococcus Tauri ◽  
In The Wild ◽  
Low Costs

AbstractOstreococcus tauri is a ubiquitous marine pico-eukaryote that is susceptible to lysis upon infection by its species specific Ostreococcus tauri viruses (OtVs). In natural populations of O. tauri, costs of resistance are usually invoked to explain the persistence or reappearance of susceptible individuals in resistant populations. Given the low costs of resistance measured in laboratory experiments with the O. tauri/OtV system to date, the question remains of why susceptible individuals persist in the wild at all. Epidemiological models of host and pathogen population dynamics are one useful approach to understand the conditions that can allow the coexistence of susceptible and resistant hosts. We used a SIR (Susceptible-Infected-Resistant) model to investigate epidemiological dynamics under different laboratory culturing regimes that are commonly used in the O.tauri/OtV system. When taking into account serial transfer (i.e. batchcycle lengths) and dilution rates as well as different resistance costs, our model predicts that no susceptible cells should be detected under any of the simulated conditions – this is consistent with laboratory findings. We thus considered an alternative model that is not used in laboratory experiments, but which incorporates one key process in natural populations: host populations are periodically re-seeded with new infective viruses. In this model, susceptible individuals re-occurred in the population, despite low costs of resistance. This suggests that periodic attack by new viruses, rather than (or in addition to) costs of resistance, may explain the high proportion of susceptible hosts in natural populations, and underlie the discrepancy between laboratory studies and observations of fresh isolates.ImportanceIn natural samples of Ostreococcus sp. and its associated viruses, susceptible hosts are common. However, in laboratory experiments, fully resistant host populations readily and irreversibly evolve. Laboratory experiments are powerful methods for studying process because they offer a stripped-down simplification of a complex system, but this simplification may be an oversimplification for some questions. For example, laboratory and field systems of marine microbes and their viruses differ in population sizes and dynamics, mixing or migration rates, and species diversity, all of which can dramatically alter process outcomes. We demonstrate the utility of using epidemiological models to explore experimental design and to understand mechanisms underlying host-virus population dynamics. We highlight that such models can be used to form strong, testable hypotheses about which key elements of natural systems need to be included in laboratory systems to make them simplified, rather than oversimplified, versions of the processes we use them to study.

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.

scholarly journals Generalisation behaviour of predators toward warning signals displayed by harmful prey: answers from a videogame played by humans

2018 ◽  
Author(s):  
Mónica Arias ◽  
David Griffiths ◽  
Mathieu Joron ◽  
John Davey ◽  
Simon Martin ◽  
...  
Keyword(s):  
Video Game ◽  
Natural Populations ◽  
Computer Game ◽  
Warning Signals ◽  
Natural Systems ◽  
Natural Predator ◽  
In The Wild ◽  
Human Predation ◽  
Colour Patterns ◽  
Set Up

AbstractThe persistence of several warning signals in sympatry is a puzzling evolutionary question because selection favours convergence of colour patterns among toxic species. Such convergence is shaped by predators’ reaction to similar but not identical stimulus, i.e. generalisation behaviour. However, studying generalisation behaviour in complex natural communities of predators is challenging, and is thus generally limited to simple variations of prey colour patterns. Here, we used humans as surrogate predators to investigate generalisation behaviours on two prey communities with different level of warning signals complexity. Humans’ generalisation capacities were estimated using a computer game simulating a simple (4 morphs) and a complex (10 morphs) community of defended (associated with a penalty) and palatable butterflies. Colour patterns used in the game are actually observed in natural populations of the defended butterflies H. numata, and generalisation behaviour of natural predator’s communities on these colour patterns have previously been investigated in the wild, allowing direct comparison with human behaviour. We investigated human predation behaviour by recording attack rates on the different defended and palatable colour patterns, as well as player survival time (i.e. score). Phenotypic similarity among the different colour patterns was precisely quantified using a custom algorithm accounting for both colour and pattern variations (CPM method). By analysing attack behaviours of 491 game players, we found that learning was more efficient in the simple prey community. Additionally, profitable prey gained protection from sharing key visual features with unprofitable prey in both communities while learning, in accordance with natural predator behaviours. Moreover, other behaviours observed in natural predators, such as colour neophobia, were detected in humans and shaped morph vulnerability during the game. Similarities between our results in humans and the reaction of natural predator communities to the same colour patterns validate our video-game as a useful proxy to study predator behaviour. This experimental set-up can thus be compared to natural systems, enabling further investigations of generalisation on mimicry evolution.

The Collection, Maintenance, and Environmental Importance, of the Genetic Resources of Wild Plants

1975 ◽  
Vol 2 (3) ◽  
pp. 223-228 ◽  
Author(s):  
Peter A. Thompson
Keyword(s):  
Wild Species ◽  
Economic Value ◽  
Natural Populations ◽  
Wild Plants ◽  
Plant Resources ◽  
Economic Resource ◽  
Factors Affecting ◽  
Natural Systems ◽  
In The Wild ◽  
Major Factors

Plants are major factors conditioning an environment, and conservation of particular environments depends fundamentally on the maintenance of existing plant communities. In many parts of the world, the destruction of such communities is occurring so rapidly and so completely that entire natural systems are subject to, or threatened with, total destruction. In such cases artificial methods of conserving plant germplasm for ultimate regeneration, for supplementing natural populations, for study, or for use by Man as an economic resource, may be of great significance as one possible means of averting total loss. Under less extreme pressures, the availability of representative propagules of significant taxa or populations may be of crucial assistance as an aid to research directed towards a better understanding of factors affecting survival or competitive advantage in the wild, or as a means of providing stocks for assessment of the potential economic value of existing reserves of wild species.This paper discusses methods of recording, maintaining, and evaluating, collections of populations of wild species. Plant resources of this kind are extremely vulnerable when maintained under artificial conditions, and a very high proportion of collections are lost within a few years, remain unavailable for general use, or fail to be used owing to inadequate documentation. Conservation of plant germ-plasm as an international resource, in a usable form, depends on a wide acceptance and practice of greatly improved methods of documentation, and requires the creation of effective organizations for surveying, maintaining, and coordinating, plant resources on an international scale.

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 Fish heating tolerance scales similarly across individual physiology and populations

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nicholas L. Payne ◽  
Simon A. Morley ◽  
Lewis G. Halsey ◽  
James A. Smith ◽  
Rick Stuart-Smith ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Tropical Species ◽  
Acclimation Temperature ◽  
Tight Coupling ◽  
Abundance Patterns ◽  
Biological Responses ◽  
In The Wild ◽  
Demographic Processes ◽  
Climate Vulnerability ◽  
Increasing Temperature

AbstractExtrapolating patterns from individuals to populations informs climate vulnerability models, yet biological responses to warming are uncertain at both levels. Here we contrast data on the heating tolerances of fishes from laboratory experiments with abundance patterns of wild populations. We find that heating tolerances in terms of individual physiologies in the lab and abundance in the wild decline with increasing temperature at the same rate. However, at a given acclimation temperature or optimum temperature, tropical individuals and populations have broader heating tolerances than temperate ones. These congruent relationships implicate a tight coupling between physiological and demographic processes underpinning macroecological patterns, and identify vulnerability in both temperate and tropical species.

An ecological explanation for hyperallometric scaling of reproduction

2021 ◽  
Author(s):  
Tomos Potter ◽  
Anja Felmy
Keyword(s):  
Body Size ◽  
Reproductive Output ◽  
Resource Competition ◽  
Natural Populations ◽  
Scaling Exponent ◽  
Wild Populations ◽  
Wet Season ◽  
Size Dependent ◽  
In The Wild ◽  
The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

Estimating the influence of temperature on the survival of chinook salmon smolts (Oncorhynchus tshawytscha) migrating through the Sacramento – San Joaquin River Delta of California

1995 ◽  
Vol 52 (4) ◽  
pp. 855-863 ◽  
Author(s):  
Peter Fritz Baker ◽  
Franklin K. Ligon ◽  
Terence P. Speed
Keyword(s):  
Water Temperature ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Logistic Function ◽  
Laboratory Findings ◽  
Natural Systems ◽  
San Joaquin River ◽  
Influence Of Temperature On ◽  
The Relationship ◽  
Good Agreement

Data from the U.S. Fish and Wildlife Service are used to investigate the relationship between water temperature and survival of hatchery-raised fall-run chinook salmon (Oncorhynchus tshawytscha) smolts migrating through the Sacramento – San Joaquin Delta of California. A formal statistical model is presented for the release of smolts marked with coded-wire tags (CWTs) in the lower Sacramento River and the subsequent recovery of marked smolts in midwater trawls in the Delta. This model treats survival as a logistic function of water temperature, and the release and recovery of different CWT groups as independent mark–recapture experiments. Iteratively reweighted least squares is used to fit the model to the data, and simulation is used to establish confidence intervals for the fitted parameters. A 95% confidence interval for the upper incipient lethal temperature, inferred from the trawl data by this method, is 23.01 ± 1.08 °C This is in good agreement with published experimental results obtained under controlled conditions (24.3 ± 0.1 and 25.1 ± 0.1 °C for chinook salmon acclimatized to 10 and 20 °C, respectively): this agreement has implications for the applicability of laboratory findings to natural systems.

scholarly journals Predators as Agents of Selection and Diversification

Diversity ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 415
Author(s):  
Jerald B. Johnson ◽  
Mark C. Belk
Keyword(s):  
Natural Selection ◽  
Empirical Evidence ◽  
Mortality Rates ◽  
Predator Species ◽  
Natural Systems ◽  
Evolutionary Diversification ◽  
Multiple Predator Species ◽  
In The Wild ◽  
Taxonomic Groups ◽  
Future Work

Predation is ubiquitous in nature and can be an important component of both ecological and evolutionary interactions. One of the most striking features of predators is how often they cause evolutionary diversification in natural systems. Here, we review several ways that this can occur, exploring empirical evidence and suggesting promising areas for future work. We also introduce several papers recently accepted in Diversity that demonstrate just how important and varied predation can be as an agent of natural selection. We conclude that there is still much to be done in this field, especially in areas where multiple predator species prey upon common prey, in certain taxonomic groups where we still know very little, and in an overall effort to actually quantify mortality rates and the strength of natural selection in the wild.

scholarly journals The sources of sex differences in aging in annual fishes

2020 ◽  
Author(s):  
Martin Reichard ◽  
Radim Blažek ◽  
Jakub Žák ◽  
Petr Kačer ◽  
Oldřich Tomášek ◽  
...  
Keyword(s):  
Sex Differences ◽  
Social Environment ◽  
Social Factors ◽  
Environmental Conditions ◽  
Natural Populations ◽  
Experimental Results ◽  
Survival Difference ◽  
Captive Populations ◽  
Baseline Mortality ◽  
In The Wild

AbstractSex differences in lifespan and aging are widespread among animals, with males usually the shorter-lived sex. Despite extensive research interest, it is unclear how lifespan differences between the sexes are modulated by genetic, environmental and social factors. We combined comparative data from natural populations of annual killifishes with experimental results on replicated captive populations, showing that females consistently outlived males in the wild. This sex-specific survival difference persisted in social environment only in two most aggressive species, and ceased completely when social and physical contacts were prevented. Demographically, neither an earlier start nor faster rate of aging accounted for shorter male lifespans, but increased baseline mortality and the lack of mortality deceleration in the oldest age shortened male lifespan. The sexes did not differ in any measure of functional aging we recorded. Overall, we demonstrate that sex differences in lifespan and aging may be ameliorated by modulating social and environmental conditions.

Sign in / Sign up

Export Citation Format

Share Document