Visibility of the environmental noise modulating population dynamics

Area of Science:

• Population ecology
• Ecological modeling
• Environmental science

Background:

• Population fluctuations are a central topic in ecology, with ongoing debate on density-dependent versus density-independent factors.
• External noise, particularly in the context of global warming, is increasingly considered a significant driver of population density changes.

Purpose of the Study:

• To investigate the correlation between modulated population dynamics and external noise signals.
• To assess the influence of low- and high-frequency noise components on population dynamics models.

Main Methods:

• Utilized Ricker dynamics and second-order autoregressive dynamics as population skeleton models.
• Superimposed noise with low- and high-frequency components onto the population dynamics.
• Analyzed correlations between modulated dynamics and noise signals across different dynamic regimes (stable, periodic, complex).

Main Results:

• High correlations (time-lag -1) were observed between population dynamics and noise in stable regions, but not in periodic or complex dynamics.
• Low-frequency noise showed minimal impact on these correlations.
• Strong correlations across all dynamics required very high noise impact, potentially distorting underlying patterns.

Conclusions:

• External noise can strongly correlate with population dynamics, particularly in stable systems.
• The presence of noise can substantially alter fitted parameter values, making underlying population dynamics difficult to recognize.
• The study questions the identifiability of intrinsic population dynamics when modulated by significant external noise.