scholarly journals Harvesting can stabilize population fluctuations and buffer the impacts of climate change

2021 ◽  
Author(s):  
Bart Peeters ◽  
Vidar GrØtan ◽  
Marlène Gamelon ◽  
Vebjørn Veiberg ◽  
Aline Magdalena Lee ◽  
...  
Keyword(s):  
Life Histories ◽  
Resource Competition ◽  
Extinction Risk ◽  
Population Models ◽  
Environmental Stochasticity ◽  
Environmental Drivers ◽  
Population Fluctuations ◽  
Vital Rates ◽  
Density Dependent ◽  
Environmental Perturbations

Harvesting can magnify the destabilizing effects of environmental perturbations on population dynamics and, thereby, increase extinction risk. However, population-dynamic theory predicts that impacts of harvesting depend on the type and strength of density-dependent regulation. Here, we used population models for a range of life histories and an empirical reindeer case study to show that harvesting can actually buffer populations against environmental perturbations. This occurs because of density-dependent environmental stochasticity, where negative environmental impacts on vital rates are amplified at high population density due to intra-specific resource competition. Simulations from our population models show that even low levels of proportional harvesting may prevent overabundance, thereby dampening population fluctuations and reducing the risk of population collapse and quasi-extinction induced by environmental perturbations. Thus, depending on the species’ life history and the strength of density-dependent environmental drivers, harvesting can improve population resistance to increased climate variability and extreme weather expected under global warming.

scholarly journals Harvesting can stabilize population fluctuations and buffer the impacts of extreme climatic events

2021 ◽  
Author(s):  
Bart Peeters ◽  
Vidar Grøtan ◽  
Marlène Gamelon ◽  
Vebjørn Veiberg ◽  
Aline Magdalena Lee ◽  
...  
Keyword(s):  
Resource Competition ◽  
Growth Models ◽  
Extinction Risk ◽  
Environmental Stochasticity ◽  
Environmental Drivers ◽  
Population Fluctuations ◽  
Vital Rates ◽  
Density Dependent ◽  
Environmental Perturbations

Harvesting can magnify the destabilizing effects of environmental perturbations on population dynamics and, thereby, increase extinction risk. However, population-dynamic theory predicts that impacts of harvesting depend on the type and strength of density-dependent regulation. Here, we used logistic population growth models and an empirical reindeer case study to show that low to moderate harvesting can actually buffer populations against environmental perturbations. This occurs because of density-dependent environmental stochasticity, where negative environmental impacts on vital rates are amplified at high population density due to intraspecific resource competition. Simulations from our population models show that even low levels of harvesting may prevent overabundance, thereby dampening population fluctuations and reducing the risk of population collapse and quasi-extinction following environmental perturbations. Thus, depending on the species’ life history and the strength of density-dependent environmental drivers, low to moderate harvesting can improve population resistance to increased climate variability and extreme weather expected under global warming.

scholarly journals From stochastic environments to life histories and back

2009 ◽  
Vol 364 (1523) ◽  
pp. 1499-1509 ◽  
Author(s):  
Shripad Tuljapurkar ◽  
Jean-Michel Gaillard ◽  
Tim Coulson
Keyword(s):  
Life History ◽  
Growth Rates ◽  
Life Histories ◽  
Life History Evolution ◽  
Environmental Stochasticity ◽  
Vital Rates ◽  
Stochastic Growth ◽  
Individual Fitness ◽  
History Evolution ◽  
Average Individual

Environmental stochasticity is known to play an important role in life-history evolution, but most general theory assumes a constant environment. In this paper, we examine life-history evolution in a variable environment, by decomposing average individual fitness (measured by the long-run stochastic growth rate) into contributions from average vital rates and their temporal variation. We examine how generation time, demographic dispersion (measured by the dispersion of reproductive events across the lifespan), demographic resilience (measured by damping time), within-year variances in vital rates, within-year correlations between vital rates and between-year correlations in vital rates combine to determine average individual fitness of stylized life histories. In a fluctuating environment, we show that there is often a range of cohort generation times at which the fitness is at a maximum. Thus, we expect ‘optimal’ phenotypes in fluctuating environments to differ from optimal phenotypes in constant environments. We show that stochastic growth rates are strongly affected by demographic dispersion, even when deterministic growth rates are not, and that demographic dispersion also determines the response of life-history-specific average fitness to within- and between-year correlations. Serial correlations can have a strong effect on fitness, and, depending on the structure of the life history, may act to increase or decrease fitness. The approach we outline takes a useful first step in developing general life-history theory for non-constant environments.

Stochastic Population Models

2021 ◽  
pp. 85-102
Author(s):  
Timothy E. Essington
Keyword(s):  
Stochastic Model ◽  
Extinction Risk ◽  
Ecological Systems ◽  
Population Models ◽  
Random Component ◽  
Deterministic Simulation ◽  
Density Dependent ◽  
State Variable ◽  
Stochastic Population Models ◽  
Core Concepts

The chapter “Stochastic Population Models” introduces the concept of stochasticity, why it is sometimes incorporated into models, the consequences of stochasticity for population models, and how these types of models are used to evaluate extinction risk. Ecological systems are (seemingly) governed by randomness, or “stochasticity.” A stochastic model is one that explicitly includes randomness in the prediction of state variable dynamics. Because these models have a random component, each model run will be unique and will rarely look like a deterministic simulation. In this chapter, simple unstructured and density-dependent models are presented to show core concepts, and extensions to structured and density-dependent models are given.

scholarly journals When rarity has costs: coexistence under positive frequency-dependence and environmental stochasticity

2017 ◽  
Author(s):  
Sebastian J. Schreiber ◽  
Masato Yamamichi ◽  
Sharon Y. Strauss
Keyword(s):  
Reproductive Success ◽  
Frequency Dependence ◽  
Resource Competition ◽  
Extinction Risk ◽  
Niche Overlap ◽  
Environmental Stochasticity ◽  
Environmental Fluctuations ◽  
Positive Frequency Dependence ◽  
Demographic Responses ◽  
Positive Frequency

AbstractStable coexistence relies on negative frequency-dependence, in which rarer species invading a patch benefit from a lack of conspecific competition experienced by residents. In nature, however, rarity can have costs, resulting in positive frequency-dependence (PFD) particularly when species are rare. Many processes can cause positive frequency-dependence, including a lack of mates, mutualist interactions, and reproductive interference from heterospecifics. When species become rare in the community, positive frequency-dependence creates vulnerability to extinction, if frequencies drop below certain thresholds. For example, environmental fluctuations can drive species to low frequencies where they are then vulnerable to PFD. Here, we analyze deterministic and stochastic mathematical models of two species interacting through both PFD and resource competition in a Chessonian framework. Reproductive success of individuals in these models is reduced by a product of two terms: the reduction in fecundity due to PFD, and the reduction in fecundity due to competition. Consistent with classical coexistence theory, the effect of competition on individual reproductive success exhibits negative frequency-dependence when individuals experience greater intraspecific competition than interspecific competition i.e., niche overlap is less than one. In the absence of environmental fluctuations, our analysis reveals that (1) a synergistic effect of PFD and niche overlap that hastens exclusion, (2) trade-offs between susceptibility to PFD and maximal fecundity can mediate coexistence, and (3) coexistence, when it occurs, requires that neither species is initially rare. Analysis of the stochastic model highlights that environmental fluctuations, unless perfectly correlated, coupled with PFD ultimately drive one species extinct. Over any given time frame, this extinction risk decreases with the correlation of the demographic responses of the two species to the environmental fluctuations, and increases with the temporal autocorrelation of these fluctuations. For species with overlapping generations, these trends in extinction risk persist despite the strength of the storage effect decreasing with correlated demographic responses and increasing with temporal autocorrelations. These results highlight how the presence of PFD may alter the outcomes predicted by modern coexistence mechanisms.

Environmental Stochasticity and Extinction Risk in a Population of a Small Songbird, the Great Tit

1998 ◽  
Vol 151 (5) ◽  
pp. 441
Author(s):  
Saether ◽  
Engen ◽  
Islam ◽  
McCleery ◽  
Perrins
Keyword(s):  
Extinction Risk ◽  
Great Tit ◽  
Environmental Stochasticity

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

scholarly journals Individual-based modelling of resource competition to predict density-dependent population dynamics: a case study with white storks

Oikos ◽  
2014 ◽  
Vol 124 (3) ◽  
pp. 319-330 ◽  
Author(s):  
Damaris Zurell ◽  
Ute Eggers ◽  
Michael Kaatz ◽  
Shay Rotics ◽  
Nir Sapir ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Resource Competition ◽  
Density Dependent ◽  
White Storks

Lack of relationship between simulated fish population responses and their life history traits: inadequate models, incorrect analysis, or site-specific factors?

2005 ◽  
Vol 62 (4) ◽  
pp. 886-902 ◽  
Author(s):  
Kenneth A Rose
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Lake Trout ◽  
Fish Population ◽  
Population Models ◽  
Site Specific ◽  
Density Dependent ◽  
Population Responses ◽  
Adult Growth ◽  
Specific Factors

Relationships between fish population responses to changes in their vital rates and commonly available life history traits would be a powerful screening tool to guide management about species vulnerability, to focus future data collection on species and life stages of concern, and to aid in designing effective habitat enhancements. As an extension of previous analyses by others, I analyzed the responses to changes in fecundity and yearling survival of age-structured matrix and individual-based population models of 17 populations comprising 10 species. Simulations of the matrix models showed that the magnitude of population responses, but not the relative order of species sensitivity, depended on the state (sustainable or undergoing excessive removals) of the population. Matrix and individual-based models predicted population responses that appeared to be unrelated to their species-level life history traits when responses were plotted on a three-end-point life history surface. Density-dependent adult growth was added to the lake trout (Salvelinus namaycush) matrix model, and simulations demonstrated the potential importance to predicted responses of density-dependent processes outside the usual spawner–recruit relationship. Four reasons for the lack of relationship between population responses and life history traits related to inadequate population models, incorrect analysis, inappropriate life history model, and important site-specific factors are discussed.

Sign in / Sign up

Export Citation Format

Share Document