Temporal variation can facilitate niche evolution in harsh sink environments

Area of Science:

• Evolutionary biology
• Ecology
• Population genetics

Background:

• Sink populations persist via immigration but face challenges adapting to harsh conditions.
• Previous research indicates demographic constraints and harshness reduce adaptive potential in sinks.
• Understanding adaptive evolution in sink environments is crucial for predicting species range dynamics.

Purpose of the Study:

• To investigate the role of temporal environmental variation in adaptive evolution within sink populations.
• To compare adaptive evolution dynamics using a quantitative-genetics model and an individual-based model.
• To determine how temporal variation influences the balance between maladaptation and adaptation in sinks.

Main Methods:

• Utilized two complementary models: a continuous-state quantitative-genetics model (fixed genetic variance) and an individual-based model (variable genetic variance).
• Simulated population and evolutionary dynamics under constant and temporally varying sink conditions.
• Analyzed the capacity for niche evolution and transitions between maladaptation and adaptation states.

Main Results:

• In constant harsh sinks, populations can remain maladapted or adapt, existing in alternative states.
• Temporal variation allows transitions between these maladaptive and adaptive states.
• Moderate temporal variation, especially slow or autocorrelated changes, facilitates adaptive evolution and niche expansion in sinks.

Conclusions:

• Temporal environmental variation can be a key driver of adaptive evolution in sink populations.
• This mechanism is particularly relevant for sinks created by biotic interactions like predation.
• Findings have implications for species range evolution, invasive species success, and disease emergence.