Abstract
The timing of germination is a key
life-history trait in plants, which is strongly affected by the strength
of seed dormancy. Continental-wide variation in seed dormancy has been
related to differences in climate and the timing of conditions suitable
for seedling establishment. However, for predictions of adaptive
potential and consequences of climatic change, information is needed
regarding the extent to which seed dormancy varies within climatic
regions and the factors driving such variation
We planted 17 Italian and 28 Fennoscandian populations ofArabidopsis thaliana in the greenhouse and at two field sites in
Italy and Sweden. To identify possible drivers of among-population
variation in seed dormancy, we examined the relationship between seed
dormancy and climate at the sites where populations were originally
sampled.
Seed dormancy was on average stronger in the Italian compared to the
Fennoscandian populations, but also varied widely within both regions.
Estimates of seed dormancy in the three maternal environments were
positively correlated, but seeds had on average stronger dormancy when
produced in the greenhouse than at the two field sites. Among
Fennoscandian populations, seed dormancy tended to increase with
increasing summer temperature and decreasing precipitation at the site
of origin. In the smaller sample of Italian populations, no significant
association was detected between mean seed dormancy and climate at the
site of origin.
The correlation between seed dormancy and climatic factors in
Fennoscandia suggests that at least some of the among-population
variation is adaptive and that climate change will affect selection on
this trait.