Summary
We conducted a greenhouse study of the effects of initial seed mass on seedling characteristics in a Panamanian population of Virola surinamensis, a canopy tree in which mean seed mass of different individuals ranges from 1.34 to 4.04g. The system is of particular interest because birds preferentially eat fruits of small-seeded plants, leaving seedlings of large-seeded individuals under conditions of potentially severe sibling competition (Howe and Vande Kerckhove 1980).
Effects of differences of mean seed mass between trees are explored using an analysis of variance, while effects of seed-mass variation within crops are demonstrated with a regression analysis. A two-way analysis of variance decisively shows effects of parental source and light condition on seedling height, leaf length, and dry shoot mass (all P<0.0001). A posteriori tests show that differences in seedling characteristics reflect differences in initial seed mass, with especially strong differences apparent in shoot mass. Regression of seedling characteristics on initial seed mass shows that variation of seed size within a crop is sufficient to influence shoot mass at 15 weeks (P<0.0001).
Effects of size differences of seeds that land adjacent to each other, either under the parent or in monkey droppings, are documented with growth of pairs of seedlings in pots. Differences in shoot height and mass at 15 weeks are evident when seeds of average size differ by only 0.2 g, and dramatic differences are evident when paired seeds differ by an average of 1.5 g. Seedlings grow more when isolated than when planted with conspecifics.
These experimental results offer indirect support for the hypothesis that small-seeded Virola parents secure an advantage in reproduction through differential dispersal, while large-seeded plants produce more competitive seedlings under their own crowns — an advantage most likely to be of importance when frugivores are scarce.
Similar content being viewed by others
References
Austenson HM, Walton PD (1970) Relationships between initial seed weight and mature plant characters in spring wheat. Can J Plant Sci 50:53–58
Burley J, Styles BT (1976) Tropical trees: variation, breeding and conservation. Academic Press, London
Croat T (1978) The flora of Barro Colorado Island. Stanford University Press, Palo Alto
Foster R (in press) Famine on Barro Colorado Island. In: The ecology of a tropical forest: seasonal rhythms and long-term changes (E. Leigh, Jr., A.S. Rand, D. Windsor, eds.), Smithsonian Institution Press. Washington
Harper J (1977) Population biology of plants. Academic Press, London
Harper JL, Lovell PH, Moore KG (1970) The shapes and sizes of seeds. Ann Rev Ecol Syst 1:327–356
Harper JL, Obeid M (1967) Influence of seed size and depth of sowing on the establishment and growth of varieties of fiber and oil seed flax. Crop Science 7, 527–532
Howe HF (1981) Dispersal of a neotropical nutmeg (Virola sebifera) by birds. Auk 98:88–98
Howe HF, Vande Kerckhove GA (1980) Nutmeg dispersal by tropical birds. Science 210:925–927
Howe HF, Vande Kerckhove GA (1981) Removal of wild nutmeg (Virola surinamensis) crops by birds. Ecology 62:1093–1106
Hulme A (1971) The Biochemistry of Fruits and Their Products. Vol 2. Academic Press, New York
Rabinowitz D (1979) Bimodal distributions of seedling weight in relation to density of Festuca paradoxa Desv. Nature 277, 297–298
Salisbury E (1942) The reproductive capacity of plants. Bell, London
Snow DW (1971) Evolutionary aspects of fruit-eating by birds. Ibis 113:194–202
Weil AT (1965) Nutmeg as a narcotic. J Econ Bot 19:194–217
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Howe, H.F., Richter, W.M. Effects of seed size on seedling size in Virola surinamensis; a within and between tree analysis. Oecologia 53, 347–351 (1982). https://doi.org/10.1007/BF00389011
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00389011