Local Adaptation Interacts with Expansion Load during Range Expansion: Maladaptation Reduces Expansion Load

Area of Science:

• Ecology
• Evolutionary Biology
• Genetics

Background:

• Species range expansions are influenced by numerous complex biotic and abiotic factors.
• Understanding genetic processes at expanding range edges is crucial for predicting species' responses to environmental change.

Purpose of the Study:

• To investigate the impact of local maladaptation and expansion load on fitness during species range expansions.
• To examine the interaction between environmental gradients and genetic drift at range edges.

Main Methods:

• Utilized spatially explicit simulations to model range expansion dynamics.
• Assessed the effects of environmental gradients and genetic drift on population fitness and expansion speed.

Main Results:

• Environmental gradients were found to reduce expansion load during range expansion.
• Increased expansion load permitted only locally adapted populations to persist at the range edge.
• Higher levels of maladaptation decreased expansion speed, leading to reduced genetic drift and increased immigration, thereby lowering expansion load.

Conclusions:

• Environmental gradients can mitigate genetic challenges during range expansions.
• Species shifting ranges due to climate change may face unexpectedly high expansion loads if climate change accelerates expansion rates.
• These findings have significant implications for conservation in the face of global climate change.