The endemic flora in the south of the Iberian Peninsula: taxonomic composition, biological spectrum, pollination, reproductive mode and dispersal

Abstract

Summary The taxonomical composition and four ecological characteristics (life form, seed-dispersal, pollination and reproductive mode) of the 553 endemic species occurring in the south of the Iberian Peninsula have been investigated. A comparative analysis of the results reveals that this endemic flora does not comply with the general patterns previously observed in local floras, Mediterranean regional floras and floras of temperate latitudes. Predominant life forms are chamaephytes (45%) and hemicryptophytes (33%). By contrast, therophytes (11%) and phanerophytes (1%) are relatively infrequent. This spectrum of life forms mirrors the altitudinal distribution of the endemic species, their seed-dispersal strategy and the type of phytocoenoses in which they occur. As far seed-dispersal is concerned, 44% of the endemic species lack any noteworthy adaptive feature. However, the results clearly suggest that this limitation in their disseminative potential has only encouraged endemicity among the therophytes inhabiting lowlands. Among chamaephytes and hemicryptophytes of medium and high altitude, there is a relatively high frequency of exozoochory and anemochory, an adaptation that has contributed to the survival of small plant populations. 91% of the endemic species are pollinated by animals (insects), and only 3 species are dioecious. The dichotomies that the above mentioned characteristics produce (herbaceous vs woody life form, animal-assisted vs abiotic seed-dispersal, animal-assisted vs abiotic pollination and dioecious vs hermaphrodite reproductive mode), have been used to plot statistically significant associations. These are three: Pollination mode is linked with the seed-dispersal strategy, life form with pollination mode, and pollination mode with the reproductive mode. These associations contrast distinctly with results of previous surveys on whole floras, a contrast which makes the singularity of the endemic flora of the Southern Iberian peninsula even more remarkable.