Wind-borne insects mediate directional pollen transfer between desert fig trees 160 kilometers apart

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 106; no. 48; pp. 20342 - 20347
• Main Authors: Ahmed, Sophia, Compton, Stephen G, Butlin, Roger K, Gilmartin, Philip M
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 01.12.2009; National Acad Sciences
• Subjects: Agaonidae; Animals; Biological Sciences; Cellular Biology; Ceratosolen arabicus; Computer Simulation; Desert Climate; Deserts; Ficus - genetics; Ficus - physiology; Ficus sycomorus; Fruit trees; Gene flow; Genetic loci; genetic markers; Genetically engineered microorganisms; Genetics, Population; Geography; Habitat fragmentation; Habitats; insect flight; Insect genetics; Insect pollination; Insects; Life Sciences; microsatellite repeats; Microsatellite Repeats - genetics; Namibia; Plant populations; Plant reproduction; Pollen; Pollen flow; pollinating insects; Pollination; Pollination - physiology; Pollinators; Polymerase Chain Reaction; Population parameters; Population structure; Seedlings; Trees; Wasps - physiology; Wind; Namibia; Namib Desert; POLLEN DISPERSAL; FICUS SYCOMORUS; SPATIAL STRUCTURE; GENE FLOW; FIG WASP; INSECTE
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.0902213106

The question of how far pollen can move between plants has implications for topics as diverse as habitat fragmentation, conservation management, and the containment of genetically modified crops. The monoecious African fig tree Ficus sycomorus L. relies on the small, short-lived, night-flying, host-specific fig wasp Ceratosolen arabicus Mayr for pollination. We used microsatellite markers to characterize a geographically isolated riparian population of F. sycomorus growing along the Ugab River in the Namib Desert, Namibia, together with paternity analysis of seedlings from known mothers, to map pollen movement within this population. In this way we tracked insect movements between individually recognizable trees by means of their pollen cargo and documented the movement of C. arabicus between known trees separated by more than 160 km, with a mean distance for confirmed successful pollination events of 88.6 km. The predominant observed movement of pollinators was in a westerly direction, toward the sea, reflecting seasonal nighttime wind direction and the wind-borne dispersal of fig wasps. Our results suggest the existence of an extensive panmictic population of trees that are well suited to overcome the effects of geographical isolation.