Parallel reduction in flowering time from de novo mutations enable evolutionary rescue in colonizing lineages

Area of Science:

• Evolutionary Biology
• Population Genetics
• Plant Sciences

Background:

• Predicting population responses to environmental change requires understanding adaptation mechanisms.
• Identifying adaptive variants and their evolutionary histories in natural populations is challenging.

Purpose of the Study:

• To investigate the genetic and evolutionary mechanisms of adaptation in Arabidopsis populations following a shift to an arid climate.
• To identify specific adaptive variants and reconstruct their evolutionary trajectories.

Main Methods:

• Genome-wide analysis of Arabidopsis populations from the Cape Verde Islands.
• Quantification of selection pressures and fitness changes.
• Evolutionary reconstructions to trace the history of adaptive variants.

Main Results:

• Evidence of genome-wide adaptation to multivariate selection pressures.
• Parallel reduction in time to flowering across islands, significantly increasing fitness.
• Convergent de novo loss-of-function mutations in the FRI and FLC genes mediated the flowering time reduction.

Conclusions:

• Rapid adaptation and evolutionary rescue occurred in response to abrupt climate change.
• Convergent evolution of loss-of-function mutations in core flowering time genes is a key mechanism for adaptation.
• The emergence and proliferation of adaptive variants coincided with population expansion.