• Seed predation

    Seed predation

    • Seed predation, often referred to as granivory, is a type of plant-animal interaction in which granivores (seed predators) feed on the seeds of plants as a main or exclusive food source, in many cases leaving the seeds damaged and not viable. Granivores are found across many families of vertebrates (especially mammals and birds) as well as invertebrates (mainly insects); thus, seed predation occurs in virtually all terrestrial ecosystems. Seed predation is commonly divided into two distinctive temporal categories, pre-dispersal and post-dispersal predation, which may involve different strategies and requirements and have different implications at the individual and population level. Nevertheless, regardless of timing, seed predation has great implications for plant population dynamics. To counterbalance effects of predation, plants have evolved defenses such as seed morphology (size, shape, toughness) and chemical defenses (secondary compounds such as tannins and alkaloids) to defend against their seed predators. However, as plants have adapted defenses to seed predation (e.g., chemical compounds), so have seed predators adapted to plant defenses (e.g., ability to detoxify chemical compounds). Thus, many interesting examples of coevolution arise from this dynamic relationship.

      Most humans are predominantly granivores, even if they eat a wide variety of other foods.

      Plant seeds are important sources of nutrition for animals across most ecosystems. Seeds contain food storage organs (e.g., endosperm) that provide nutrients to the developing plant embryo (cotyledon). This makes seeds an attractive food source for animals because they are a highly concentrated and localized nutrient source in relation to other plant parts.

      Seeds of many plants have evolved a variety of defenses to deter predation from seed predators. Plants may allocate resources toward physical or chemical defenses. Seeds are often contained inside protective structures or fruit pulp that encapsulate seeds until they are ripe. Other physical defenses include spines, hairs, fibrous seed coats and hard endosperm. Seeds, especially in arid areas, may have a mucilaginous seed coat that can glue soil to seed hiding it from granivores.

      • Alexander, H.M., Cummings, C.L., Kahn, L., and Snow, A.A. 2001. Seed size variation and predation of seeds produced by wild and crop–wild sunflowers. American Journal of Botany. 2001;88:623–627.
      • Andersen, A.N. 1989. How Important Is Seed Predation to Recruitment in Stable Populations of Long-Lived Perennials? Oecologia, Vol. 81, No. 3, pp. 310–315.
      • Berenbaum, M.R and Zangerl, AR. 1998. Chemical phenotype matching between a plant and its insect herbivore. Proceedings of the national academy of sciences, USA, 95, 13743-13784.
      • Brown, J.H., and E.J. Heske. 1990. Control of a desert-grassland transition by a keystone rodent guild. Science 250:1705–1707.
      • Brown, J.H., Reichman, O.J., and Davidson, D.W. 1979. Granivory in desert ecosystems. Annual Review of Ecology and Systematics, Vol. 10, pp. 201–227.
      • Davidson, D.W.. 1993. The Effects of Herbivory and Granivory on Terrestrial Plant Succession. Oikos, Vol. 68, No. 1, pp. 23–35.
      • Davidson, D.W., Brown, J.H., and Inouye, R.S. 1980. Competition and the Structure of Granivore Communities. BioScience, Vol. 30, No. 4, pp. 233–238.
      • Diaz, M., and Telleria, J.L. 1996.Granivorous Birds in a Stable and Isolated Open Habitat within the Amazonian Rainforest. Journal of Tropical Ecology, Vol. 12, No. 3, pp. 419–425.
      • Figueroa Javier A., Muñoz Alejandro A., Mella Jorge E., Arroyo Mary T. K.. 2002. Pre- and post-dispersal seed predation in a Mediterranean-type climate montane sclerophyllous forest in central Chile. Australian Journal of Botany 50, 183–195.
      • Lundgren, J and Rosentrater, K. 2007. The strength of seeds and their destruction by granivorous insects. Arthropod-plant interactions, Vol. 1, number 2.
      • Mares, M.A. and Rosenzweig, M.L.. 1978. Granivory in North and South American Deserts: Rodents, Birds, and Ants. Ecology, Vol. 59, No. 2, pp. 235–241.
      • Oliveras, J., Gomez, C., Bas, M., Espadaler, X. 2008. Mechanical Defence in Seeds to Avoid Predation by a Granivorous Ant. Naturwissenschaften. Volume 95, Number 6.
      • Sallabanks, R. and Courtney, S.P. 1992. Frugivory, Seed Predation and Insect- Vertebrate Interactions. Annual Review of Entomology. 37:337–400.
      • Smith, CC. 1970. The coevolution of pine squirrels (Tamiasciurus) and conifers. Ecological monographis, 40, 349–371.
      • Vander Wall, S.B., Kuhn, K.M., and M.J. Beck. 2005. Seed Removal, Seed Predation, and Secondary Dispersal. Ecology, Vol. 86, No. 3, pp. 801–806.
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    • Seed predation