Competition–colonization trade-off
In ecology, the competition–colonization trade-off is a stabilizing mechanism that has been proposed to explain species diversity in some biological systems, especially those that are not in equilibrium.[1][2] In which case some species are particularly good at colonizing and others have well-established survival abilities.[3] The concept of the competition-colonization trade-off was originally proposed by Levins and Culver, the model indicated that two species could coexist if one had impeccable competition skill and the other was excellent at colonizing.[4] The model indicates that there is typically a trade-off, in which a species is typically better at either competing or colonizing. A later model, labelled The Lottery Model was also proposed, in which interspecific competition is accounted for within the population.
Mathematical Models:
Levins and Culver Model:
dp1/dt = c1p1(1 - p1) - m1p1. dp2/dt = c2p2(1 - p1 - p2) - m2p2 - c1p1p2.
Where: pi = fraction of patches that are occupied by a species(i). ci = colonization rate of species(i). mi = mortality rate, independent of patch density.
Species 1 = competitor, can colonize in area that is not inhabited by species 2 (1 - p1).
Species 2 = colonizer, can only colonize in uninhabited areas (1 - p1 - p2).
Species 2 is subject to predator displacement (- c1p1p2).
If species 2 has a higher colonization rate it can coexist with species 1 (c2 > c12/m).
This model is described as the displacement competition model, it has been observed in marine mollusks and fungi. This model makes two large assumptions: 1. "a propagule of a superior competitor takes over a patch from an adult of the inferior competitor".[5] 2. The adult must be displaced fast enough to ensure that it does not reproduce while it is being displaced.
Lottery Model:
dp1/dt = c1(f/(f + p2))p1(h - p1 - p2) m1p1. dp2/dt = c2(g/(g + p1))p2(h - p1 - p2) m2p2.
Colonization rate is now described by interspecific competition.
(f/(f + p2)) and (g/(g + p1)). Both f and g > 0.
An increase in p1 is related to a decrease in the colonization rate of species 2.
g < f implies a competitive advantage of species 1 and c2 > c1 implies a colonization advantage for species 2.
In Plants:
The competition-colonization trade-off theory has primarily been used to examine and describe the dispersal-linked traits of a plant's seeds.[6] Seed size is a primary feature that relates to a species ability to colonize or compete within a given population, the effect of seed size was displayed in dicotyledonous annual plants.[7] Turnbull and colleagues indicated that the competition/colonization trade-off has a stabilizing effect on the population of plants.
In Algae:
For example, in a classic study on an intertidal zone in Southern California,[8] it was shown that when a boulder was overturned, it would quickly be colonized by green algae and barnacles (which were better colonizers). However, if left undisturbed, the boulders would eventually be overtaken by red algae (which was the stronger competitor in the long term).
See also
References
- ^ Hastings, Alan (December 1980). "Disturbance, coexistence, history, and competition for space". Theoretical Population Biology. 18 (3): 363–373. doi:10.1016/0040-5809(80)90059-3.
- ^ Cadotte, Marc William (April 2007). "Competition-colonization trade-offs and disturbance effects at multiple scales". Ecology. 88 (4): 823–829. ISSN 0012-9658. PMID 17536699.
- ^ Calcagno, V; Mouquet, N; Jarne, P; David, P (2006). "Coexistence in a metacommunity: the competition– colonization trade-off is not dead". Ecology Letters. 9: 897–907.
- ^ Levins, R; Culver, D (1971). "Regional coexistence of species and competition between rare species". Proceedings of the National Academy of Sciences of the USA. 6: 1246–1248.
- ^ Yu, D; Wilson, H (2001). "The Competition-Colonization Trade-off Is Dead; Long Live the Competition-Colonization Trade-off". The American Naturalist. 158: 49–63.
- ^ Cadotte, M; Mai, D; Collins, M; Keele, M; Drake, J (2006). "On testing the competition-colonization trade-off in a multispecies assemblage". The American Naturalist. 168: 704–709.
- ^ Turnbull, L; Coomes, D; Hector, A; Rees, M (2004). "Seed mass and the competition/colonization trade-off: competitive interactions and spatial patterns in a guild of annual plants". Journal of Ecology. 92: 97–109.
- ^ Sousa, Wayne P. (December 1979). "Disturbance in Marine Intertidal Boulder Fields: The Nonequilibrium Maintenance of Species Diversity". Ecology. 60 (6): 1225. doi:10.2307/1936969.