Climate-mediated selection, deep complex morphophysiological dormancy, embryo growth, interpopulation variability

The main goal of this work was to relate the germinative ecology and genetic variability of Chaerolhyllum aureum L., an Apiaceae plant with dormant, underdeveloped embryos at the time of seed dispersal. We compared the seed germination physiology traits between a relictic geographically isolated Mediterranean population (Iberian System; central Spain) and a population located in the main, colder Atlantic Alpine core (Pyrenees; northern Spain). We analyzed both populations? genetic identity in parallel on the basis of ISSR?PCR analyses. Stratification, gibberellin treatment, and seed storage tests showed that C. aureum seeds have deep complex morphophysiological dormancy. The Iberian System population seeds required shorter cold stratification than the Pyrenees population seeds (16 vs. 20 weeks) to germinate. The genetic analyses suggested closer similarity between Iberian System individuals and those from the Pyrenees requiring shorter cold periods to germinate. Our findings denote a consistent parallelism between germination physiology and genetic identity. The records from these germination and genetic analyses suggested selective pressure due to the climate differences between the two geographical regions. Thus, the individuals in the Iberian System population would have been selected from the original pool to a shorter cold-stratification requiring ecotype.