scholarly journals Intra‐ and interspecific density dependence mediates weather effects on the population dynamics of a plant–insect herbivore system

Oikos ◽  
2021 ◽  
Author(s):  
Peter A. Hambäck
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Insect Herbivore ◽  
Weather Effects

scholarly journals Effects of temporal variation in temperature and density dependence on insect population dynamics

Ecosphere ◽  
2016 ◽  
Vol 7 (5) ◽  
Author(s):  
C. V. Haridas ◽  
Lance J. Meinke ◽  
Bruce E. Hibbard ◽  
Blair D. Siegfried ◽  
Brigitte Tenhumberg
Keyword(s):  
Population Dynamics ◽  
Temporal Variation ◽  
Density Dependence ◽  
Insect Population ◽  
Insect Population Dynamics

scholarly journals The Effect of Conspecific Density on Emergence ofLestes bipupillatusCalvert, 1909 (Odonata: Lestidae)

2014 ◽  
Vol 2014 ◽  
pp. 1-3 ◽  
Author(s):  
Ricardo Cardoso-Leite ◽  
Gabriel C. Vilardi ◽  
Rhainer Guillermo-Ferreira ◽  
Pitágoras C. Bispo
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Social Environment ◽  
Growth Rates ◽  
High Density ◽  
Conspecific Density ◽  
Simulated Environments ◽  
The Social ◽  
Emergence Date

Conspecific density may influence adult recruitment and consequently population dynamics. Several studies have shown the density dependence of larvae growth rates in Odonata. However, few studies studied how conspecific density influence final instar larvae emergence date decisions. Considering that larvae may choose the date of emergence, the present study investigated if density affects larvae choice. For this, we reared eight final instar larvae in individual aquaria and other 24 larvae in aquaria with three larvae each. This way, we simulated environments with low and high larval densities. We then noted the days that larvae took to emerge and compared it between low and high density groups. The results showed that larvae seem to emerge earlier when in high densities (Mann-Whitney,U=10.000,P=0.03). These results support the hypothesis that damselfly last instar larvae may postpone or hasten emergence in response to the social environment and related constraints.

Population dynamics of muskrats and mink: investigating contemporary patterns in a classic predator-prey system

2021 ◽  
Author(s):  
Adam A Ahlers ◽  
Timothy P Lyons ◽  
Edward J Heske
Keyword(s):  
United States ◽  
Population Dynamics ◽  
Density Dependence ◽  
American Mink ◽  
Population Cycles ◽  
The United States ◽  
Parameter Estimates ◽  
Predator Prey ◽  
Cycle Lengths ◽  
Southern Half

A well-studied predator-prey relationship between American mink (Neovison vison (Schreber, 1777)) and muskrats (Ondatra zibethicus (Linnaeus, 1766)) in Canada has advanced our understanding of population cycles including the influence of density dependence and lagged responses of predators to prey abundances. However, it is unclear if patterns observed in Canada extend across the southern half of their native range. We used data from the United States to create a 41-year time series of mink and muskrat harvest reports (1970-2011) for 36 states. After controlling for pelt-price effects, we used 2nd order autoregressive and Lomb-Scargle spectral density models to identify the presence and periodicity of muskrat population cycles. Additionally, we tested for evidence of delayed or direct density dependence and for predator-driven population dynamics. Our results suggest muskrat populations may cycle in parts of the United States; however, results varied by modeling approaches with Lomb-Scargle analyses providing more precise parameter estimates. Observed cycle lengths were longer than expected with weak amplitudes and we urge caution when interpreting these results. We did not detect evidence of a predator-prey relationship driven by a lagged numerical response of American mink. American mink and muskrat fur returns were largely correlated across the region suggesting extraneous factors likely synchronize both populations.

Ecological change points: The strength of density dependence and the loss of history

2017 ◽  
Author(s):  
José M. Ponciano ◽  
Mark L. Taper ◽  
Brian Dennis
Keyword(s):  
Time Series ◽  
Population Dynamics ◽  
Density Dependence ◽  
Change Point ◽  
Likelihood Estimation ◽  
Theory And Practice ◽  
Change Points ◽  
Ecological Change ◽  
Proposed Model ◽  
Change Point Model

AbstractChange points in the dynamics of animal abundances have extensively been recorded in historical time series records. Little attention has been paid to the theoretical dynamic consequences of such change-points. Here we propose a change-point model of stochastic population dynamics. This investigation embodies a shift of attention from the problem of detecting when a change will occur, to another non-trivial puzzle: using ecological theory to understand and predict the post-breakpoint behavior of the population dynamics. The proposed model and the explicit expressions derived here predict and quantify how density dependence modulates the influence of the pre-breakpoint parameters into the post-breakpoint dynamics. Time series transitioning from one stationary distribution to another contain information about where the process was before the change-point, where is it heading and how long it will take to transition, and here this information is explicitly stated. Importantly, our results provide a direct connection of the strength of density dependence with theoretical properties of dynamic systems, such as the concept of resilience. Finally, we illustrate how to harness such information through maximum likelihood estimation for state-space models, and test the model robustness to widely different forms of compensatory dynamics. The model can be used to estimate important quantities in the theory and practice of population recovery.

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