Dispersal, Variability, and Transient Niches: Species Coexistence in a Uniformly Variable Environment

Observations of communities of sessile organisms, notably plants and territorial fishes, have revealed species guilds which are hard to reconcile with the competitive-exclusion principle, which forbids the persistence of multiple competitors for exactly the same resource. Several mechanisms have been proposed to account for such cases. We show in particular that random environmental variation, with no long-term spatial inhomogeneity (i.e., a uniformly variable environment), can promote species' coexistence in models of lottery competition for establishment sites. We explain this as a result of relatively intense competition in patches favoring the currently more numerous species, which occurs in multiple-patch uniformly-variable-environment models with dispersal. Time dispersal (nonsynchronous establishment of offspring of an adult cohort) has a similar and complementary effect. Simulations show that the persistence of a competitively inferior species may involve rare environmental patches that have fortuitous runs of conditions favorable to that species. We infer that the spatial distributions of rarer species in sessile organism guilds may be highly clumped.

[1]  Peter Chesson,et al.  Coexistence of Competitors in Spatially and Temporally Varying Environments: A Look at the Combined Effects of Different Sorts of Variability , 1985 .

[2]  Ilkka Hanski,et al.  Coexistence of Competitors in Patchy Environment , 1983 .

[3]  Peter Chesson,et al.  The stabilizing effect of a random environment , 1982 .

[4]  H. Comins.  Evolutionarily stable strategies for localized dispersal in two dimensions. , 1982, Journal of theoretical biology.

[5]  P. Chesson,et al.  Environmental Variability Promotes Coexistence in Lottery Competitive Systems , 1981, The American Naturalist.

[6]  Richard Levins,et al.  Coexistence in a Variable Environment , 1979, The American Naturalist.

[7]  Coexistence of Competitors , 1979 .

[8]  J. Harper.  Population Biology of Plants , 1979 .

[9]  P. Sale.  Maintenance of High Diversity in Coral Reef Fish Communities , 1977, The American Naturalist.

[10]  P. Grubb.  THE MAINTENANCE OF SPECIES‐RICHNESS IN PLANT COMMUNITIES: THE IMPORTANCE OF THE REGENERATION NICHE , 1977 .

[11]  J. Gillespie.  The role of migration in the genetic structure of populations in temporally and spatially varying environments. II. Island models. , 1976, Theoretical population biology.

[12]  J. Felsenstein.  The theoretical population genetics of variable selection and migration. , 1976, Annual review of genetics.

[13]  Montgomery Slatkin,et al.  Competition and Regional Coexistence , 1974 .

[14]  R. Macarthur,et al.  Competition among Fugitive Species in a Harlequin Environment , 1972 .

[15]  S. Levin.  Community Equilibria and Stability, and an Extension of the Competitive Exclusion Principle , 1970, The American Naturalist.

[16]  R. Levins.  Evolution in Changing Environments , 1968 .

[17]  R. Macarthur,et al.  COMPETITION, HABITAT SELECTION, AND CHARACTER DISPLACEMENT IN A PATCHY ENVIRONMENT. , 1964, Proceedings of the National Academy of Sciences of the United States of America.

[18]  G. Tullock,et al.  Competitive Exclusion. , 1960, Science.

[19]  G. Hardin.  The competitive exclusion principle. , 1960, Science.

[20]  M. Kimura,et al.  'Stepping stone' model of population , 1953 .

[21]  W. Feller.  An Introduction to Probability Theory and Its Applications , 1959 .

[22]  Feller William,et al.  An Introduction To Probability Theory And Its Applications , 1950 .