A local dormancy cline is related to the seed maturation environment, population genetic composition and climate

Abstract

Background and Aims Seed dormancy varies within species in response to climate, both in the long term (through ecotypes or clines) and in the short term (through the influence of the seed maturation environment). Disentangling both processes is crucial to understand plant adaptation to environmental changes. Here we investigated the local patterns of seed dormancy in a narrow endemic species, Centaurium somedanum, to determine the influence of the seed maturation environment, population genetic composition and climate. Methods We performed laboratory germination experiments to measure dormancy in (1) seeds collected from different wild populations along a local altitudinal gradient and (2) seeds of a subsequent generation produced in a common garden. We characterized the genetic composition of the original populations using Inter-Simple Sequence Repeat PCR and PCoA, and analyzed its correlation to the dormancy patterns of both generations. We also modelled the effect of the local climate on dormancy. Key Results We found an altitudinal dormancy cline in the wild populations, which was maintained by the plants grown in the common garden. However, seeds from the common garden responded better to stratification, and their release from dormancy was more intense. The patterns of dormancy variation were correlated to genetic composition; while lower temperature and summer precipitation at the population sites predicted higher dormancy in the seeds of both generations. Conclusions The dormancy cline in C. somedanum is related to a local climatic gradient and also corresponds with genetic differentiation among populations. This cline is further affected by the weather conditions during seed maturation, which influence the receptiveness to dormancy-breaking factors. These results show that dormancy is influenced both by long and short term climatic variation. Such processes at such a reduced spatial scale highlight the potential of plants to adapt to fast environmental changes.