Effects of Incubation Temperature on Seed Germination of Mediterranean Plants with Different Geographical Distribution Ranges

Little is known about consequences of the increasing global temperatures on seed germination and even less about the seed germination response of species with different geographical distribution ranges. In the present work, the effect of incubation temperature on seed germination of 31 species from the Iberian Peninsula is analyzed in relation to their geographical distribution range. We tested whether plants with different geographical distribution ranges (Iberian Peninsula endemics, Mediterranean, widely distributed species), respond similarly to incubation temperature using cross-species analysis as well as taking into account phylogenetic relationships among species. Seeds were incubated at 10A degrees C, 15A degrees C, 20A degrees C and 25A degrees C for 6 weeks in darkness. Distribution range appeared as a determinant of germination response to the temperature treatment independent of phylogeny. Widely distributed species were less sensitive than endemic or Mediterranean species to incubation temperatures, which may represent an advantage to colonize new areas or to tolerate changes in the environment. Although their ability to avoid germination during the warm and dry season might be favorable for endemic species in some situations, our results also suggest that under a future of temperature increase imposed by climate change, endemic plant species may be more vulnerable than widely distributed species.