Hutchinson's Ratio
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In
ecological Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...
theory, the Hutchinson's ratio is the
ratio In mathematics, a ratio () shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ...
of the size differences between similar
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
when they are living together as compared to when they are isolated. It is named after G. Evelyn Hutchinson who concluded that various key attributes in species varied according to the ratio of 1:1.1 to 1:1.4. Hutchinson concluded that the mean ratio, 1.3, can be understood as the variation of attribute separation needed in order to preserve species coexistence at the same
trophic level The trophic level of an organism is the position it occupies in a food web. Within a food web, a food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the ...
but in differing niches. However, some authors present evidence that this ratio does not depict the structure of animal communities. Rather, Hutchinson's ratio is just a representation of the
distribution Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a varia ...
of entities, both living and non-living, in nature. A study was conducted by R. Charles MacNally to test whether sympatric species form geometric series, also known as a Hutchinsonian series. The results of this revealed that only a small fraction of the series conformed to the expected ratio of 1.3, questioning the accuracy of Hutchinson's ratio.


See also

* Hutchinson's rule


References


External links

* *https://web.archive.org/web/20010228025300/http://www.limnology.org/news/30/hutchinson.html Ecology {{ecology-stub