scholarly journals Contrasting effects of spatial heterogeneity and environmental stochasticity on population dynamics of a perennial wildflower

2016 ◽  
Vol 104 (2) ◽  
pp. 281-291 ◽  
Author(s):  
Elizabeth E. Crone
Keyword(s):  
Population Dynamics ◽  
Spatial Heterogeneity ◽  
Environmental Stochasticity

scholarly journals Explaining Spatial Heterogeneity in Population Dynamics and Genetics from Spatial Variation in Resources for a Large Herbivore

PLoS ONE ◽  
2012 ◽  
Vol 7 (10) ◽  
pp. e47858 ◽  
Author(s):  
Adrienne L. Contasti ◽  
Emily J. Tissier ◽  
Jill F. Johnstone ◽  
Philip D. McLoughlin
Keyword(s):  
Population Dynamics ◽  
Spatial Heterogeneity ◽  
Spatial Variation ◽  
Large Herbivore

The population dynamics of aphids on fire weed: a comparison of local populations and metapopulations

1978 ◽  
Vol 56 (12) ◽  
pp. 2554-2564 ◽  
Author(s):  
John F. Addicott
Keyword(s):  
Population Dynamics ◽  
Spatial Heterogeneity ◽  
Rocky Mountains ◽  
Median Number ◽  
Marked Variation ◽  
High Frequencies ◽  
Local Populations ◽  
Epilobium Angustifolium ◽  
Population Processes ◽  
Different Levels

Local populations of four species of aphids (Macrosiphum Valerianae, Aphis varions, A. helianthi, and A. salicariae) occur on shoots of fireweed (Epilobium angustifolium) in the Rocky Mountains of Colorado, U.S.A. Through exhaustive and repeated nondestructive sampling of the local populations on over 3800 shoots of fireweed, information was obtained on the dynamics of both the local populations and the metapopulation of each species. The dynamics of the metapopulation were analyzed in terms of the frequency of shoots occupied by aphids and the median number of aphids per occupied shoot. There were significant differences between species in both parameters, but high densities were not necessarily accompanied by high frequencies. Local populations were initiated throughout the summer, and there was marked variation in the duration and size of these populations. Most populations lasted only a few weeks, but others lasted up to 14 weeks. This turnover of local populations within the metapopulation implies that local populations must be studied in order to understand the dynamics of the metapopulation. There is a discussion of the relationships between population processes occurring at different levels of spatial heterogeneity.

scholarly journals Breeding transients in capture–recapture modeling and their consequences for local population dynamics

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniel Oro ◽  
Daniel F. Doak
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Population Growth Rate ◽  
Local Population ◽  
Environmental Stochasticity ◽  
Adult Survival ◽  
Local Survival ◽  
First Reproduction ◽  
Capture Recapture

Abstract Standard procedures for capture–mark–recapture modelling (CMR) for the study of animal demography include running goodness-of-fit tests on a general starting model. A frequent reason for poor model fit is heterogeneity in local survival among individuals captured for the first time and those already captured or seen on previous occasions. This deviation is technically termed a transience effect. In specific cases, simple, uni-state CMR modeling showing transients may allow researchers to assess the role of these transients on population dynamics. Transient individuals nearly always have a lower local survival probability, which may appear for a number of reasons. In most cases, transients arise due to permanent dispersal, higher mortality, or a combination of both. In the case of higher mortality, transients may be symptomatic of a cost of first reproduction. A few studies working at large spatial scales actually show that transients more often correspond to survival costs of first reproduction rather than to permanent dispersal, bolstering the interpretation of transience as a measure of costs of reproduction, since initial detections are often associated with first breeding attempts. Regardless of their cause, the loss of transients from a local population should lower population growth rate. We review almost 1000 papers using CMR modeling and find that almost 40% of studies fitting the searching criteria (N = 115) detected transients. Nevertheless, few researchers have considered the ecological or evolutionary meaning of the transient phenomenon. Only three studies from the reviewed papers considered transients to be a cost of first reproduction. We also analyze a long-term individual monitoring dataset (1988–2012) on a long-lived bird to quantify transients, and we use a life table response experiment (LTRE) to measure the consequences of transients at a population level. As expected, population growth rate decreased when the environment became harsher while the proportion of transients increased. LTRE analysis showed that population growth can be substantially affected by changes in traits that are variable under environmental stochasticity and deterministic perturbations, such as recruitment, fecundity of experienced individuals, and transient probabilities. This occurred even though sensitivities and elasticities of these parameters were much lower than those for adult survival. The proportion of transients also increased with the strength of density-dependence. These results have implications for ecological and evolutionary studies and may stimulate other researchers to explore the ecological processes behind the occurrence of transients in capture–recapture studies. In population models, the inclusion of a specific state for transients may help to make more reliable predictions for endangered and harvested species.

scholarly journals Global Production Increased by Spatial Heterogeneity in a Population Dynamics Model

2005 ◽  
Vol 53 (4) ◽  
pp. 359-370 ◽  
Author(s):  
J.-C. Poggiale ◽  
P. Auger ◽  
D. Nérini ◽  
C. Manté ◽  
F. Gilbert
Keyword(s):  
Population Dynamics ◽  
Spatial Heterogeneity ◽  
Dynamics Model ◽  
Population Dynamics Model

scholarly journals Cooperative and non-cooperative behaviour in the exploitation of a common renewable resource with environmental stochasticity

2020 ◽  
Author(s):  
Michael Hackney ◽  
Alex James ◽  
Michael J. Plank
Keyword(s):  
Population Dynamics ◽  
Stochastic Game ◽  
Economic Value ◽  
Renewable Resource ◽  
Fishing Effort ◽  
Environmental Stochasticity ◽  
Agent Based ◽  
Stock Biomass ◽  
Optimal Policies ◽  
Fisheries Biology

AbstractClassical fisheries biology aims to optimise fisheries-level outcomes, such as yield or profit, by controlling the fishing effort. This can be adjusted to allow for the effects of environmental stochasticity, or noise, in the population dynamics. However, when multiple fishing entities, which could represent countries, commercial organisations, or individual vessels, can autonomously determine their own fishing effort, the the optimal action for one fishing entity depends on the actions of others. Coupled with noise in the population dynamics, and with decisions about fishing effort made repeatedly, this becomes an iterated stochastic game. We tackle this problem using the tools of stochastic optimisation, first for the monopolist’s problem and then for the duopolist’s problem. In each case, we derive optimal policies that specify the best level of fishing effort for a given stock biomass. Under these optimal policies, we can calculate the equilibrium stock biomass, the expected long-term return from fishing and the probability of stock collapse. We also show that there is a threshold stock biomass below which it is optimal to stop fishing until the stock recovers. We then develop an agent-based model to test the effectiveness of simple strategies for responding to deviations by an opponent from a cooperative fishing level. Our results show that the economic value of the fishery to a monopolist, or to a consortium of fishing agents, is robust to a certain level of noise. However, without the means of making agreements about fishing effort, even low levels of noise make sustained cooperation between autonomous fishing agents difficult.

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