ena-STUDY-Max Planck Intitute for Plant Breeding Research-17-06-2020-15:38:02:038-539
Parallel loss of function at major flowering time loci underlie adaptive rescue in colonising Arabidopsis lineages
During environmental change, small populations confront high extinction risk due to limited genetic variation and reduced efficiency of selection. Here, we reconstruct the colonisation and adaptive history of Arabidopsis populations from the Cape Verde Islands, which lie at the edge of the species distribution, to examine how populations adapt to sudden and extreme environmental change. Cape Verde populations migrated via long-range dispersal from the Moroccan Atlas mountains resulting in an immediate shift to a climate defined by a short growing season and limited, highly variable rainfall. We find that adaptation occurred via parallel reduction in flowering time across islands and that this shift to early flowering was mediated largely by three large-effect variants: a loss of function in FLC on one island and of FRI in the other. Evolutionary reconstructions reveal that these variants appeared early in the history of island populations and rapidly rose in frequency, consistent with a role in rescue from extinction. Our results reveal a central role for new large effect variants in the evolutionary rescue of fragile small populations during environmental change scenarios.
During environmental change, small populations confront high extinction risk due to limited genetic variation and reduced efficiency of selection. Here, we reconstruct the colonisation and adaptive history of Arabidopsis populations from the Cape Verde Islands, which lie at the edge of the species distribution, to examine how populations adapt to sudden and extreme environmental change. Cape Verde populations migrated via long-range dispersal from the Moroccan Atlas mountains resulting in an immediate shift to a climate defined by a short growing season and limited, highly variable rainfall. We find that adaptation occurred via parallel reduction in flowering time across islands and that this shift to early flowering was mediated largely by three large-effect variants: a loss of function in FLC on one island and of FRI in the other. Evolutionary reconstructions reveal that these variants appeared early in the history of island populations and rapidly rose in frequency, consistent with a role in rescue from extinction. Our results reveal a central role for new large effect variants in the evolutionary rescue of fragile small populations during environmental change scenarios.