Spreading recruitment over time to cope 4 with environmental variability 5 Rita

8 Abstract Seedling establishment is one of the most 9 vulnerable life cycle stages, and a key component for 10 the population dynamics in short-lived plants. In 11 unpredictable environments, timing of emergence is 12 critical for the success of plant performance, and 13 different adaptive bet-hedging strategies have evolved 14 to reduce the risk of failure in recruitment. In this 15 study we describe the spatio-temporal pattern of 16 seedling emergence (overall rate and timing) and 17 survival in four contrasting Mediterranean habitats for 18 Plantago coronopus, a small herb with dimorphic 19 seeds. We then explore the importance of spreading 20 germination within years, as well as the role of the two 21 types of seeds from a broader temporal perspective. 22 Populations strongly differed for all recruitment 23 components analyzed in a given year, but this spatial 24 differentiation diluted when a longer period was 25 considered. Apical (smaller) seeds germinated later 26 and in a significantly lower proportion than basal 27 (larger) seeds. Both late emergents and seedlings from 28 apical seeds had lower survival probability in a rainy 29 year. However, our results suggest that in a population 30 having the lowest production of apical seeds, late 31 emergents coming from apical seeds may constitute a 32 large fraction of yearly recruitment and that their 33 performance was non-significantly different from that 34 of early emergents over the 4-year study period. This 35 study provides evidence of the importance of two 36 related traits (spreading seedling emergence through 37 time by producing dimorphic seeds) as bet-hedging 38 strategies to cope with environmental unpredictabil39 ity. This is at least partly accomplished by increasing 40 the potential of recruitment in favourable years, 41 instead of buffering such important process in 42 extremely bad years.