Rapid changes in phenotype distribution during range expansion in a migratory bird

Area of Science:

• Ecology
• Evolutionary Biology
• Ornithology

Background:

• Species' ability to adapt to environmental changes drives population and range dynamics.
• Local adaptation can limit species' expansion, while disperser fitness impacts population growth.
• Studying these processes is crucial for conservation but rarely feasible at relevant scales.

Purpose of the Study:

• Investigate eco-evolutionary feedbacks in Icelandic black-tailed godwits (Limosa limosa islandica) during their recent range expansion.
• Determine the relationship between male morphology, habitat quality, and breeding success in this expanding population.

Main Methods:

• Analyzed spatial variation in male godwit morphology across Iceland.
• Correlated male size with the timing of habitat colonization.
• Assessed the relationship between male abundance, female abundance, breeding success, and habitat quality.

Main Results:

• Male morphology in Icelandic black-tailed godwits strongly correlates with colonization timing; smaller males are absent from recently colonized areas.
• Smaller males are more abundant in high-quality habitats with greater breeding success and higher female densities.
• This spatial structuring suggests female preference for smaller males and habitat quality influence fitness and dispersal.

Conclusions:

• Female preference for smaller males and habitat quality drive spatial structuring of male morphology in Icelandic black-tailed godwits.
• Eco-evolutionary feedbacks, influenced by male morphology and habitat selection, likely regulate population growth and range dynamics.
• These findings offer insights into species' responses to environmental change and inform conservation strategies.