Seed Dispersal

Abstract

The sedentary life of adult plants accentuates the critical importance of the short phase during which individual plants move: the dispersal of seeds, a common, widespread and fascinating phenomenon. Ultimately, selective pressures favouring dispersal include inbreeding avoidance, reduction of competition with kin and nonkin and the tracking of establishment opportunities in time and space. Proximately, dispersal mechanisms include nonrandom release from the mother plant, and transport by multiple dispersal vectors not necessarily those inferred from the seed morphology. The resulting patterns, often described by dispersal kernels, typically show a decline in seed deposition with distance from the source and a tail of long‐distance dispersal events. Yet, environmental heterogeneity may cause more complex dispersal patterns. Dispersal has important consequences for the fate of individuals, populations, communities and ecosystems, enabling metapopulations and metacommunities to persist and playing a critical role in shaping the evolutionary and plastic response of plants to changing environments.

Key concepts

  • Dispersal is a widespread phenomenon among plants, selected to avoid inbreeding, to reduce competition with kin and nonkin and to cope with spatiotemporally variable environments.

  • Causes for dispersal evolution act in concert, interact and may affect differently the evolution of short‐ and long‐distance dispersal.

  • Seeds typically depart from the source plant in a nonrandom fashion, suggesting selection to coordinate seed release with favourable conditions for dispersal and/or establishment.

  • Seeds of a given plant species are typically dispersed by multiple vectors, including ‘nonstandard’ vectors differing from those inferred from the seed morphology.

  • Dispersal kernels describe how seed deposition varies – in one, two or three spatial dimensions – in relation to the distance from the seed source.

  • One‐dimensional dispersal kernels generally show a decline in seed number (or density) with distance, and a ‘fat’ tail implying more long‐distance dispersal events than expected from a negative exponential distribution.

  • Complex dispersal kernels arise because seed deposition often varies not only with distance but also with direction and environmental heterogeneity.

  • Dispersal plays a key role in allowing plants to adapt to climate changes, to spread within and outside their native range and to maintain metapopulations and metacommunities.

  • New methods to model the underlying mechanisms, to analyze gene flow and genetic structure and to quantify dispersal patterns increase our understanding and predictability of seed dispersal in general, and long‐distance dispersal in particular.

Keywords: seed dispersal; long‐distance dispersal; dispersal kernels; gene flow; spatial spread

Figure 1.

Example of a one‐dimensional dispersal distance kernel (a probability density function of dispersal distance). Note that the lognormal kernel shown here has both a convex shape near the source and a fat tail. The fat tail of the lognormal kernel bends away from the x‐axis in a semilog plot (insert). Hence, it drops more slowly than the tail of any exponential kernel (thin lines).

Figure 2.

A complex two‐dimensional dispersal density kernel. The right‐hand part of the figure shows the two‐dimensional equivalent of the dispersal distance kernel in Figure . The left‐hand part shows secondary peaks of seed deposition and areas behind these peaks where seed deposition is decreased.

Figure 3.

A schematic of how the different dispersal kernels of two species relate to dynamics at different scales. Most seeds of species A (solid line) fall within the local population, but it has a large tail which allows exchange of seeds among regional populations. Species B (dashed line) has a further modal dispersal distance than A, but this causes many seeds to disperse out of the local population. The tail is relatively thin so there is little exchange of seeds among regional populations. Population spread involves the whole kernel.

close

References

Acosta FJ, Delgado JA, Lopez E and Serrano JM (1997) Functional features and ontogenetic changes in reproductive allocation and partitioning strategies of plant modules. Plant Ecology 132: 71–76.

Buckley YM, Brockerhoff E, Langer L et al. (2005) Slowing down a pine invasion despite uncertainty in demography and dispersal. Journal of Applied Ecology 42: 1020–1030.

Bullock JM, Moy IL, Pywell RF et al. (2002) Plant dispersal and colonization processes at local and landscape scales. In: Bullock JM, Kenward RE and Hails R (eds) Dispersal Ecology, pp. 279–302. Malden, MA: Blackwell.

Bullock JM and Nathan R (2008) Plant dispersal across multiple scales: linking models and reality. Journal of Ecology 96: 567–568.

Bullock JM, Pywell RF and Coulson‐Phillips SJ (2008) Managing plant population spread: prediction and analysis using a simple model. Ecological Applications 18: 945–953.

Carlo TA and Morales JM (2008) Inequalities in fruit‐removal and seed dispersal: consequences of bird behaviour, neighbourhood density and landscape aggregation. Journal of Ecology 96: 609–618.

Cheptou PO, Carrue O, Rouifed S and Cantarel A (2008) Rapid evolution of seed dispersal in an urban environment in the weed Crepis sancta. Proceedings of the National Academy of Sciences of the USA 105: 3796–3799.

Clark JS, Silman M, Kern R, Macklin E and HilleRisLambers J (1999) Seed dispersal near and far: patterns across temperate and tropical forests. Ecology 80: 1475–1494.

Dennis AJ and Westcott DA (2007) Estimating dispersal kernels produced by a diverse community of vertebrates. In: Dennis AJ, Green RJ, Schupp EW and Westcott DA (eds) Seed Dispersal: Theory and Its Application in a Changing World, pp. 201–228. Wallingford, UK: CAB International.

Donohue K, Polisetty CR and Wender NJ (2005) Genetic basis and consequences of niche construction: plasticity‐induced genetic constraints on the evolution of seed dispersal in Arabidopsis thaliana. American Naturalist 165: 537–550.

Gardner RH and Engelhardt KAM (2008) Spatial processes that maintain biodiversity in plant communities. Perspectives in Plant Ecology Evolution and Systematics 9: 211–228.

Greene DE (2005) The role of abscission in long‐distance seed dispersal by the wind. Ecology 86: 3105–3110.

Hamilton WD and May RM (1977) Dispersal in stable habitats. Nature 269: 578–581.

Hampe A (2004) Extensive hydrochory uncouples spatiotemporal patterns of seedfall and seedling recruitment in a ‘bird‐dispersed’ riparian tree. Journal of Ecology 92: 797–807.

Harper JL (1977) Population Biology of Plants. London: Academic Press.

Herrera CM (1984) A study of avian frugivores, bird‐dispersed plants, and their interaction in Mediterranean scrublands. Ecological Monographs 54: 1–23.

Higgins SI, Clark JS, Nathan R et al. (2003a) Forecasting plant migration rates: managing uncertainty for risk assessment. Journal of Ecology 91: 341–347.

Higgins SI, Nathan R and Cain ML (2003b) Are long‐distance dispersal events in plants usually caused by nonstandard means of dispersal? Ecology 84: 1945–1956.

Hutchings MJ and de Kroon H (1994) Foraging in plants: the role of morphological plasticity in resource acquisition. Advances in Ecological Research 25: 159–238.

Imbert E and Ronce O (2001) Phenotypic plasticity for dispersal ability in the seed heteromorphic Crepis sancta (Asteraceae). Oikos 93: 126–134.

Izhaki I, Walton PB and Safriel UN (1991) Seed shadows generated by frugivorous birds in an Eastern Mediterranean scrub. Journal of Ecology 79: 575–590.

Janzen DH (1970) Herbivores and the number of tree species in tropical forests. American Naturalist 104: 501–528.

Jongejans E, Skarpaas O and Shea K (2008) Dispersal, demography and spatial population models for conservation and control management. Perspectives in Plant Ecology Evolution and Systematics 9: 153–170.

Jordano P, Garcia C, Godoy JA and Garcia‐Castano JL (2007) Differential contribution of frugivores to complex seed dispersal patterns. Proceedings of the National Academy of Sciences of the USA 104: 3278–3282.

Kalisz S, Hanzawa FM, Tonsor SJ, Thiede DA and Voigt S (1999) Ant‐mediated seed dispersal alters pattern of relatedness in a population of Trillium grandiflorum. Ecology 80: 2620–2634.

Katul GG, Porporato A, Nathan R et al. (2005) Mechanistic analytical models for long‐distance seed dispersal by wind. American Naturalist 166: 368–381.

Klein EK, Lavigne C and Gouyon PH (2006) Mixing of propagules from discrete sources at long distance: comparing a dispersal tail to an exponential. BMC Ecology 6:3, doi:10.1186/1472‐6785‐6‐3.

Kuparinen A (2006) Mechanistic models for wind dispersal. Trends in Plant Science 11: 296–301.

Leibold MA, Holyoak M, Mouquet N et al. (2004) The metacommunity concept: a framework for multi‐scale community ecology. Ecology Letters 7: 601–613.

Linhart YB and Grant MC (1996) Evolutionary significance of local genetic differentiation in plants. Annual Review of Ecology and Systematics 27: 237–277.

Martínez I, García D and Obeso JR (2008) Differential seed dispersal patterns generated by a common assemblage of vertebrate frugivores in three fleshy‐fruited trees. Ecoscience 15: 189–199.

Muller‐Landau HC, Wright SJ, Calderon O, Condit R and Hubbell SP (2008) Interspecific variation in primary seed dispersal in a tropical forest. Journal of Ecology 96: 653–667.

Murray KG (1988) Avian seed dispersal of three neotropical gap‐dependent plants. Ecological Monographs 58: 271–298.

Nathan R and Katul GG (2005) Foliage shedding in deciduous forests lifts up long‐distance seed dispersal by wind. Proceedings of the National Academy of Sciences of the USA 102: 8251–8256.

Nathan R and Muller‐Landau HC (2000) Spatial patterns of seed dispersal, their determinants and consequences for recruitment. Trends in Ecology & Evolution 15: 278–285.

Nathan R, Schurr FM, Spiegel O et al. (2008) Mechanisms of long‐distance seed dispersal. Trends in Ecology & Evolution 23: 638–647.

van der Pijl L (1982) Principles of Dispersal in Higher Plants, 3rd edn. Berlin: Springer.

Ravigné V, Olivieri I, González‐Martínez SC and Rousset F (2006) Selective interactions between short‐distance pollen and seed dispersal in self‐compatible species. Evolution 60: 2257–2271.

Ridley HN (1930) The Dispersal of Plants throughout the World. Ashford: Reeve.

Schmitt J and Gamble SE (1990) The effect of distance from the parental site on offspring performance and inbreeding depression in Impatiens capensis: a test of the local adaptation hypothesis. Evolution 44: 2022–2030.

Schurr FM, Steinitz O and Nathan R (2008) Plant fecundity and seed dispersal in spatially heterogeneous environments: models, mechanisms and estimation. Journal of Ecology 96: 628–641.

Skarpaas O, Auhl R and Shea K (2006) Environmental variability and the initiation of dispersal: turbulence strongly increases seed release. Proceedings of the Royal Society B – Biological Sciences 273: 751–756.

Soons MB and Bullock JM (2008) Non‐random seed abscission, long‐distance wind dispersal and plant migration rates. Journal of Ecology 96: 581–590.

Soons MB and Ozinga WA (2005) How important is long‐distance seed dispersal for the regional survival of plant species? Diversity and Distributions 11: 165–172.

Stiles EW (1980) Patterns of fruit presentation and seed dispersal in bird‐disseminated woody‐plants in the eastern deciduous forest. American Naturalist 116: 670–688.

Stoyan D and Wagner S (2001) Estimating the fruit dispersion of anemochorous forest trees. Ecological Modelling 145: 35–47.

Vander Wall SB and Longland WS (2004) Diplochory: are two seed dispersers better than one? Trends in Ecology & Evolution 19: 155–161.

Wenny DG (2001) Advantages of seed dispersal: a re‐evaluation of directed dispersal. Evolutionary Ecology Research 3: 51–74.

Willson MF (1993) Dispersal mode, seed shadows, and colonization patterns. Vegetatio 107/108: 261–280.

Wright SJ, Trakhtenbrot A, Bohrer G et al. (2008) Understanding strategies for seed dispersal by wind under contrasting atmospheric conditions. Proceedings of the National Academy of Sciences of the USA 105: 19084–19089.

Further Reading

Bullock JM, Kenward RE and Hails R (eds) (2002) Dispersal Ecology. Malden: Blackwell.

Clobert J, Danchin E, Dhondt AA and Nichols JD (eds) (2001) Dispersal. Oxford: Oxford University Press.

Cousens R, Dytham C and Law R (2008) Dispersal in Plants: A Population Perspective. Oxford: Oxford University Press.

Dennis AJ, Schupp EW, Green RJ and Westcott DA (eds) (2007) Seed Dispersal: Theory and Its Application in a Changing World. Wallingford, UK: CAB International.

Fenner M and Thompson K (2005) The Ecology of Seeds. Cambridge, UK: Cambridge University Press.

Forget PM, Lambert JE, Hulme PE and Vander Wall SB (eds) (2004) Seed Fate: Predation, Dispersal and Seedling Establishment. Wallingford, UK: CAB International.

Levey DJ, Silva WR and Galetti M (eds) (2002) Seed Dispersal and Frugivory: Ecology, Evolution and Conservation. Wallingford: CAB International.

Contact Editor close
Submit a note to the editor about this article by filling in the form below.

* Required Field

How to Cite close
Nathan, Ran, Bullock, James M, Ronce, Ophélie, and Schurr, Frank M(Sep 2009) Seed Dispersal. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0021225]