Increased adaptive potential in novel environments can be predicted from genetic variance in development time...

While developmental plasticity helps organisms to maintain fitness as environments change, such plasticity has limits. When novel environments exceed these limits and mean fitness declines, the extent of decline is expected to vary among genotypes, which could increase adaptive potential. We lack fundamental insights into whether genetic variation in early development is linked to adaptive potential in novel environments, which limits our ability to predict how natural populations will respond to global change. Using a breeding design, we generated c. 20,000 seeds of 2 ecologically contrasting Sicilian species of daisies (Senecio, Asteraceae) adapted to high and low elevations on Mount Etna. We planted the seeds across 4 elevations that included elevations within the native range of each species, the edge of their range, and a novel elevation. We tracked seedling mortality and measured development time as the number of days it took seedlings to establish. As predicted, genetic variance in survival increased at novel elevations, suggesting that adaptive potential consistently increases for contrasting species facing different novel environments. However, genetic variance in development time showed the opposite trend, decreasing at novel elevations. A strong negative genetic correlation between development time in the native range and survival at novel elevations suggested that genotypes with faster development in native environments survived better in novel environments. These results were consistent across the two ecologically contrasting species, suggesting that genetic variance in early development in native environments could be used to predict genotypes that increase adaptive potential in novel environments.