Increasing environmental variability inhibits evolutionary rescue in a long-lived vertebrate

Area of Science:

• Ecology
• Evolutionary Biology
• Conservation Biology

Background:

• Evolutionary rescue is theorized to help populations persist amid anthropogenic change.
• Evidence for evolutionary rescue in wild populations remains limited.
• Long-lived species may face unique challenges adapting to rapid environmental shifts.

Purpose of the Study:

• To investigate if Magellanic penguins (Spheniscus magellanicus) can morphologically adapt to long-term environmental change for population persistence.
• To assess the viability of evolutionary rescue as an adaptation process in a free-ranging vertebrate species.
• To understand the role of fluctuating selection in inhibiting adaptation.

Main Methods:

• Analysis of a 38-year dataset of 53,959 Magellanic penguins.
• Investigation of morphological changes in response to environmental variability.
• Eco-evolutionary modeling to project population persistence under climate change.

Main Results:

• Penguins did not exhibit significant morphological adaptation to long-term environmental changes.
• Fluctuating selection, driven by environmental variability, benefited different penguin sizes inconsistently.
• Projected population extirpation under future climate scenarios, indicating a lack of evolutionary rescue.
• Inhibition of adaptation due to fluctuating selection under increasing environmental variability.

Conclusions:

• Morphological adaptation was insufficient to promote population persistence in Magellanic penguins.
• Fluctuating selection can impede evolutionary rescue in species facing environmental change.
• The findings suggest constraints on adaptation for long-lived species, with implications for conservation strategies.
• Eco-evolutionary dynamics are crucial for understanding species' responses to global environmental change.