Altered precipitation dynamics lead to a shift in herbivore dynamical regime

Area of Science:

• Ecology
• Population Dynamics
• Climate Science

Background:

• Population dynamics are influenced by interactions between internal biological factors and external environmental changes.
• While changes in average climate are well-studied, alterations in environmental variability also impact population dynamics significantly.
• This study examines a 34-year moth census in California, analyzing shifts in population oscillations and regional precipitation patterns.

Discussion:

• Wavelet and time series analyses revealed a regime shift in moth population dynamics, transitioning from shorter to longer period oscillations.
• These changes coincided with alterations in regional precipitation dynamics, suggesting a causal link.
• Simulations indicated that shifting precipitation patterns likely drove the observed changes in moth population dynamics, potentially through stochastic resonance with delayed density-dependence.

Key Insights:

• A significant regime shift was identified in California moth population dynamics over 34 years.
• The study links this shift to contemporaneous changes in regional precipitation dynamics.
• Climate variability, not just mean climate, plays a critical role in population dynamics.

Outlook:

• Predicting future population dynamics requires understanding both climatic shifts and their interplay with endogenous density-dependence.
• Current models based solely on historical data may fail to predict future population trends due to these complex interactions.
• Further research is needed to integrate climate variability into ecological forecasting models.