Adaptation to habitat in Aquilegia species endemic to Sardinia (Italy): Seed dispersal, germination and persistence in the soil

Abstract

The autecology of the Sardinian endemics Aquilegia barbaricina Arrigoni et Nardi and A. nugorensis Arrigoni et Nardi were investigated. Peaks of anthesis and seed dispersal were recorded for five populations occurring in two distinct habitats, one riparian and one rupicolous. Germination tests were carried out on seed lots belonging to each population by sowing seeds at 10, 15, 20, 25 and 25/15°C. In addition, seeds were incubated for 2 months at either 25°C (summer), 5°C (winter) or 25°C for 2 months plus 2 months at 5°C (summer followed by winter–SW), and then moved to the germination temperatures. Embryo measurements were taken during pre-treatments and germination. Experimental seed burials were carried out for two populations of each species. Both species dispersed in summer. The population of A. nugorensis occurring on rocky outcrops differed in phenology from both the other A. nugorensis population from riparian vegetation and from A. barbaricina. Both species showed morphophysiological seed dormancy, with <50% germination under laboratory conditions. All riparian populations germinated only after the SW pre-treatment, while the rupicolous population germinated at 25°C, without any pre-treatment. Low germination percentages were observed in the experimental seed burials, suggesting the ability for both species to form a persistent soil seed bank.

Keywords:

• Mediterranean region
• morphophysiological dormancy
• narrow endemics
• persistent soil seed bank
• seed dispersal

Acknowledgements

The authors thank A. Congiu for help with fieldwork and Z. Cook (SCD, Kew) for help with germination scoring and embryo measurements. The support of the Seed Conservation Department, Royal Botanic Gardens, Kew is gratefully acknowledged. The Centre for the Conservation of Biodiversity (CCB) is supported by the “Provincia di Cagliari – Assessorato Tutela Ambiente”. This research was also supported by the “RAS – Assessorato Difesa dell'Ambiente.”