Lottery competition in
ecology
Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...
is a model for how organisms
compete
Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indivi ...
. It was first used to describe competition in coral reef fish.
Under lottery competition, many offspring compete for a small number of sites (e.g., many
fry competing for a few territories, or many seedlings competing for a few
treefall gap
A treefall gap is a distinguishable hole in the canopy of a forest with vertical sides extending through all levels down to an average height of above ground. These holes occur as result of a fallen tree or large limb. The ecologist who develop ...
s). Under lottery competition, one individual is chosen randomly to "win" that site (typically becoming an adult soon after), and the "losers" typically die off. Thus, in an analogy to a lottery or
raffle
A raffle is a gambling competition in which people obtain numbered tickets, each of which has the chance of winning a prize. At a set time, the winners are drawn at random from a container holding a copy of each number. The drawn tickets are che ...
, every individual has an equal chance of winning (like every ticket has an equal chance of being chosen), and therefore more abundant species are proportionately more likely to win (just as an individual who buys more tickets is more likely to win).
Some models
generalize this idea by weighting some individuals who are more likely to be chosen (by analogy, this would be like some tickets counting as two tickets instead of one). When a population is below
carrying capacity, e.g. due to
ecological disturbance
In ecology, a disturbance is a temporary change in environmental conditions that causes a pronounced change in an ecosystem. Disturbances often act quickly and with great effect, to alter the physical structure or arrangement of biotic and abiotic ...
, then producing twice as many individuals is not identical to producing individuals twice as likely to win; the two specialized groups can coexist in a
competition-colonization trade-off.
Lottery competition has been used to in understanding many key ideas in ecology, including the
storage effect (species coexist because they are affected differently by environmental variation)
and
neutral theory Neutral theory may refer to one of these two related theories:
* Neutral theory of molecular evolution
* Unified neutral theory of biodiversity
The unified neutral theory of biodiversity and biogeography (here "Unified Theory" or "UNTB") is a t ...
(species diversity is maintained because species are competitively equivalent, and extinction rates are slow enough to be offset by speciation and dispersal events).
[{{cite book, last1=Hubbell, first1=Stephen P., title=The unified neutral theory of biodiversity and biogeography, date=2001, publisher=Princeton University Press, location=Princeton, N.J., isbn=978-0-691-02129-4, edition=Print on Demand.]
References
Ecology