Shifting Vital Rate Correlations Alter Predicted Population Responses to Increasingly Variable Environments

Area of Science:

• Ecology
• Population Dynamics
• Demography

Background:

• Stochastic population projections often use time series of vital rates.
• This approach is considered "environment-blind" and used to assess population growth elasticity to vital rate variance.

Purpose of the Study:

• To investigate the limitations of "environment-blind" population projections.
• To determine how shifts in vital rate correlations under increasing environmental variability affect demographic analyses.

Main Methods:

• Analysis of vital rate time series.
• Evaluation of shifts in vital rate correlations under varying environmental drivers.
• Assessment of fitness effects across different life histories.

Main Results:

• The utility of "environment-blind" projections is significantly limited by unpredictable shifts in vital rate correlations.
• These shifts have the most substantial impact on species with short to medium generation times.
• Comparative analyses using elasticities to vital rate variance may be unreliable for many species.

Conclusions:

• Shifts in vital rate correlations are common in variable environments.
• Environmentally explicit models are crucial for accurate population predictions.
• Further research is needed to identify species requiring mechanistic models versus those sufficient with summarized demographic data.