title: On the Limited Potential of Azorean Fleshy Fruits for Oceanic Dispersal.
abstract: How plants arrived to originally sterile oceanic islands has puzzled naturalists for centuries. Dispersal syndromes (i.e., diaspore traits that promote dispersal by long-distance dispersal vectors), are generally considered to play a determinant role in assisting island colonization. However, the association between diaspore traits and the potential vectors by which diaspores are dispersed is not always obvious. Fleshy fruits, in particular, are considered to have evolved to promote the internal dispersal of seeds by frugivores (endozoochory), however some fleshy fruits can also float in saltwater, and thus be potentially transported by oceanic current (thalassochory). We performed saltwater floatation and viability experiments with fruits of the 14 European fleshy-fruited species that naturally colonized the Azores archipelago (North Atlantic Ocean). We show that only Corema album (a berry) and Juniperus oxycedrus (a fleshy cone) floated for as long as 60 days, the estimated minimum time needed to reach the Azores by oceanic currents. Regardless the floatation potential, exposure to saltwater largely reduced the viability of most seeds of the 14 species (46% of viability decline within 15 days and 77% within 60 days of immersion), including those of Corema album (61%) and Juniperus oxycedrus (83%). Floatability and viability trials suggest that while some fleshy-fruited species might have arrived to the Azores by oceanic currents, such would have required extreme meteorological events that could largely reduce the duration of the trip. Thus, the alternative hypothesis that fleshy-fruited species were mostly dependent on animal dispersers (endozoochory) to colonize these remote islands is reinforced.
authors.affiliation: Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
authors.forename: Carolina Franco
authors.initials: CF
authors.lastname: Esteves
authors.affiliation: Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Costa
authors.affiliation: Real Jardín Botánico de Madrid (CSIC-RJB), Madrid, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Vargas
authors.affiliation: Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
authors.forename: Helena
authors.initials: H
authors.lastname: Freitas
authors.affiliation: Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
authors.forename: Ruben Huttel
authors.initials: RH
authors.lastname: Heleno
mesh_terms: D025041:Animal Migration / Q000502:physiology; D000818:Animals; D001267:Atlantic Ocean; D001394:Azores; D029791:Ericaceae / Q000502:physiology*; D005638:Fruit / Q000033:anatomy & histology / Q000502:physiology; D018653:Juniperus / Q000502:physiology*; D063148:Plant Dispersal / Q000502:physiology*; D012492:Salts / Q000494:pharmacology; D012623:Seawater / Q000737:chemistry; D012639:Seeds / Q000187:drug effects / Q000502:physiology*; D014872:Water Movements
chemical_list: D012492:Salts