Evolutionary responses to a changing climate: Implications for reindeer population viability

Area of Science:

• Ecology
• Evolutionary Biology
• Climate Change Biology

Background:

• Understanding resource allocation trade-offs (reproduction vs. survival) is crucial for long-lived organisms facing climate change.
• The interplay between density-independent (DI) and density-dependent (DD) processes in shaping life histories remains unclear.

Purpose of the Study:

• To investigate how density-independent and density-dependent processes interact to influence the evolution of reproductive strategies and population dynamics in female reindeer (Rangifer tarandus).
• To model reindeer reproductive allocation under varying winter climatic scenarios.

Main Methods:

• Developed a seasonal state-dependent model for reindeer.
• Simulated various winter climatic scenarios, manipulating average conditions, variability, and frequency of good/poor winters.
• Analyzed the effects of these scenarios on reproductive allocation and population dynamics.

Main Results:

• Both density-dependent and density-independent processes significantly affected reindeer reproductive allocation and population dynamics.
• These effects were observed even when DI and DD processes were confounded (e.g., harsh climates leading to lower density).
• Individual reindeer exhibited risk-sensitive reproductive allocation strategies in response to climatic conditions.

Conclusions:

• Density-dependent and density-independent processes interact to shape the evolution of reproductive strategies and population dynamics in reindeer.
• Reindeer exhibit adaptive, risk-sensitive reproductive strategies in response to environmental variability and climate change.
• The findings highlight the complex ecological responses of large herbivores to changing environmental conditions.