Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

The breeding structure of a tropical keystone plant resource


Despite the recognized importance of maintaining viable populations of keystone plant resources in tropical wildlife parks and forested preserves, the critical question of what constitutes effective breeding units of these species has not been directly addressed. Here we use paternity analysis techniques to reconstruct the genotypes of pollen donor trees and to estimate pollen dispersal distances and breeding population size parameters for Panamanian populations of seven species of monoecious strangler figs (Ficus, Moraceae), a particularly widespread and influential group of keystone producers1,2,3. Despite the minute size (1–2 mm) and short lifespan (2–3 d) of the species-specific wasp pollinators (Agaonidae, Chalcidoidea), pollen dispersal was estimated to occur routinely over distances of 5.8–14.2 km between widely spaced host trees. As a result of such extensive pollen movement, breeding units of figs comprise hundreds of intermating individuals distributed over areas of 106–632 km2, an order of magnitude larger than has been documented for any other plant species. Moreover, these results should be generalizable to the 350 or so monoecious fig species that share this pollination system4. The large areal extent of breeding units of these keystone plant resources has important implications for our understanding of both the evolution of tropical biodiversity and its maintenance by applied conservation efforts.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Similar content being viewed by others


  1. Leighton, M. & Leighton, D. R. in Tropical Rain Forest: Ecology and Management(eds Sutton, S. L., Whitmore, T. C. & Chadwick, A. C.) 181–196 (Blackwell, Oxford, (1983)).

    Google Scholar 

  2. Terborgh, J. in Conservation Biology. The Science of Scarceness and Diversity(ed. Soulé, M. E.) 330–344 (Sinauer, Sunderland, MA, (1986)).

    Google Scholar 

  3. Lambert, F. R. & Marshall, A. G. Keystone characteristics of bird dispersed Ficus in a Malaysian lowland rain forest. J. Ecol. 79, 793–809 (1991).

    Article  Google Scholar 

  4. Wiebes, J. T. Agaonidae (Hymenoptera, Chalcidoidea) and Ficus (Moracease): fig wasps and their figs, xv (Meso-American Pegoscapus). Proc. K. Ned. Akad. Wet. 98, 167–183 (1995).

    Google Scholar 

  5. Todzia, C. Growth habits, host tree species, and density of hemiepiphytes on Barro Colorado Island, Panama. Biotropica 18, 22–27 (1986).

    Article  Google Scholar 

  6. Windsor, D. M., Morrison, D. W., Estribi, M. A. & Leon, B. D. Phenology of fruit and leaf production by ‘strangler’ figs on Barro Colorado Island, Panamá. Experimentia 45, 647–653 (1989).

    Article  Google Scholar 

  7. Janzen, D. H. How to be a fig. Annu. Rev. Ecol. Syst. 10, 13–51 (1979).

    Article  Google Scholar 

  8. Hamrick, J. L. in Proceedings of the International Symposium on Genetic Conservation and Production of Tropical Forest Tree Seed(eds Drysdale, R. M., John, S. E. T. & Yapa, A. C.) 1–9 (Asean-Canada Forest Tree Seed Centre, (1994)).

    Google Scholar 

  9. Herre, E. A. Coevolution of reproductive characteristics in 12 species of New World figs and their pollinator wasps. Experientia 45, 637–647 (1989).

    Article  Google Scholar 

  10. Herre, E. A. et al. Molecular phylogenies of figs and their pollinating wasps. J. Biogeogr. 23, 521–530 (1996).

    Article  Google Scholar 

  11. Ware, A. B. & Compton, S. G. Dispersal of adult female fig wasps. 1. Arrivals and departures. Entemol. Exp. Appl. 73, 221–229 (1994).

    Article  Google Scholar 

  12. Ware, A. B. & Compton, S. G. Dispersal of adult female fig wasps. 2. Movements between trees. Entemol. Exp. Appl. 73, 231–238 (1994).

    Article  Google Scholar 

  13. Compton, S. G. Acollapse of host specificity in some South African fig wasps. S. African J. Sci. 86, 39–40 (1990).

    Google Scholar 

  14. Compton, S. G., Ross, S. J. & Thornton, I. W. B. Pollinator limitation of fig tree reproduction on the island of Anak Krakatau (Indonesia). Biotropica 26, 180–186 (1994).

    Article  Google Scholar 

  15. McKey, D. Population biology of figs: applications for conversation. Experientia 45, 661–673 (1989).

    Article  Google Scholar 

  16. Nason, J. D., Aldrich, P. R. & Hamrick, J. L. in Tropical Forest Remnants: Ecology, Management and Conservation of Fragmented Communities(eds Laurance, W. F. & Bierregaard, R. O. Jr) 304–320 (University of Chicago Press, Chicago, (1997)).

    Google Scholar 

  17. Bierregaard, R. O. J., Lovejoy, T. E., Kapos, V., Santos, A. A. D. & Hutchings, R. W. The biological dynamics of tropical rainforest fragments: A prospective comparison of fragments and continuous forest. Bioscience 42, 859–866 (1992).

    Article  Google Scholar 

  18. Kjellberg, F. & Maurice, S. Seasonality in the reproductive phenology of Ficus: its evolution and consequences. Experientia 45, 653–660 (1989).

    Article  Google Scholar 

  19. Bronstein, J. L., Gouyon, P.-H., Gliddon, C., Kjellberg, F. & Michaloud, G. The ecological consequences of flowering asynchrony in monoecious figs: a simulation study. Ecology 71, 2145–2156 (1990).

    Article  Google Scholar 

  20. Anstett, M. C., Hossaert-McKey, M. & McKey, D. Modelling the persistence of small populations of strongly interdependent species of figs and fig wasps. Conserv. Biol. 11, 204–213 (1997).

    Article  Google Scholar 

  21. Thomson, J. D., Herre, E. A., Hamrick, J. L. & Stone, J. L. Genetic mosaics in strangler fig trees: implications for tropical conservation. Science 254, 1214–1216 (1991).

    Article  ADS  CAS  Google Scholar 

  22. Burnham, K. P. & Overton, W. S. Robust estimation of population size when capture probabilities vary among animals. Ecology 60, 927–936 (1979).

    Article  Google Scholar 

  23. Levin, D. A. The paternity pools of plants. Am. Nat. 132, 309–317 (1988).

    Article  Google Scholar 

  24. Eguiarte, L. E., Pérez-Nasser, N. & Pinero, D. Genetic structure, outcrossing rate and heterosis in Astrocaryum mexicanum (tropical palm): implications for evolution and conservation. Heredity 69, 217–228 (1992).

    Article  CAS  Google Scholar 

  25. Stacy, E. A. et al. Pollen dispersal in low density populations of three neutropical tree species. Am. Nat. 148, 275–298 (1996).

    Article  Google Scholar 

  26. Boshier, D. H., Chase, M. R. & Bawa, K. S. Population genetics of Cordia alliodora (Boraginaceae), a neotropical tree. 3. Gene flow, neighborhood, and population structure. Am. J. Bot. 82, 484–490 (1995).

    Article  Google Scholar 

  27. Chase, M. R., Moller, C., Kessell, R. & Bawa, K. S. Distant gene flow in tropical trees. Nature 383, 398–399 (1996).

    Article  ADS  CAS  Google Scholar 

  28. Nason, J. D. & Hamrick, J. L. Reproductive and genetic consequences of forest fragmentation: two case studies of Neotropical canopy trees. J. Hered. 88, 264–276 (1997).

    Article  Google Scholar 

  29. Wright, J. Pollen-dispersion studies: some practical applications. J. Forest. 51, 114–118 (1953).

    Google Scholar 

  30. Bannister, M. H. in The Genetic of Colonizing Species(eds Baker, H. G. & Stebbins, G. L.) 353–372 (Academic, New York, (1965)).

    Google Scholar 

  31. Adams, W. T. Gene dispersal within forest tree populations. New Forests 6, 217–240 (1992).

    Article  Google Scholar 

Download references


We thank P. Aldrich, N. Ellstrand, T. Fleming, M. J. Godt, A. Graffen, K. Harms, M.Harris, E. Kalko, E. Leigh, R. May, K. Milton, S. Rand, J. Thomson and N. Waser for discussion. This work was supported by a grant from the NSF and was greatly aided by the Smithsonian Tropical Research Institute and its facilities on BCI.

Author information

Authors and Affiliations


Corresponding author

Correspondence to John D. Nason.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Nason, J., Herre, E. & Hamrick, J. The breeding structure of a tropical keystone plant resource. Nature 391, 685–687 (1998).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing