Jordan's rule

Jordan's rule (sense 1) is an ecogeographical rule that describes the inverse relationship between water temperature and meristic characteristics in various species of fish. The most commonly observed relationship is that fin ray, vertebrae, or scale numbers increase with decreasing temperature. The rule is named after David Starr Jordan (1851–1931), the father of American ichthyology.^[1]

Jordan's law (or rule) (sense 2) is also an ecogeographical rule (named after the same scientist) that states: "‘[g]iven any species in any region, the nearest related species is not likely to be found in the same region nor in a remote region, but in a neighbouring district separated from the first by a barrier of some sort’^[2] This "rule" is frequently violated (see discussion in Fitzpatrick & Turelli 2007^[3]), but when patterns are consistent with Jordan's rule (sense 2), this suggests an important role for allopatric speciation in the diversification of the clade in question.^[4]^[5] Jordan himself wrote: "To this generalization Dr. Allen, in a late number of Science, gives the name of 'Jordan's Law.' The present writer makes no claim to the discovery of this law. The language above quoted is his, but the idea is familiar to all students of geographical distribution and goes back to the master in that field, Moritz Wagner."^[6]^[7] Thus, Jordan's law is an example of Stigler's law.

References

^ McDowall, R. M. (March 2008). "Jordan's and other ecogeographical rules, and the vertebral number in fishes". Journal of Biogeography. 35 (3): 501–508. doi:10.1111/j.1365-2699.2007.01823.x.
^ Jordan, David Starr (1908-02-01). "The Law of Geminate Species". The American Naturalist. 42 (494): 73–80. doi:10.1086/278905. ISSN 0003-0147.
^ Fitzpatrick, Benjamin M.; Turelli, Michael (2006). "The Geography of Mammalian Speciation: Mixed Signals from Phylogenies and Range Maps". Evolution. 60 (3): 601–615. doi:10.1111/j.0014-3820.2006.tb01140.x. ISSN 1558-5646. PMID 16637504. S2CID 32663278.
^ Mayr, Ernst, 1904-2005. (1963). Animal species and evolution. Cambridge: Belknap Press of Harvard University Press. ISBN 0-674-03750-2. OCLC 551391.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
^ Barraclough, Timothy G. (20 June 2019). The evolutionary biology of species (First ed.). Oxford. ISBN 978-0-19-106665-8. OCLC 1104724041.{{cite book}}: CS1 maint: location missing publisher (link)
^ Jordan, David Starr (February 1908). "The Law of Geminate Species". The American Naturalist. 42 (494): 73–80. doi:10.1086/278905. ISSN 0003-0147.
^ Allen, J. A. (October 1907). "Mutations and the Geographic Distribution of Nearly Related Species in Plants and Animals". The American Naturalist. 41 (490): 653–655. doi:10.1086/278852. ISSN 0003-0147.

[1] McDowall, R. M. (March 2008). "Jordan's and other ecogeographical rules, and the vertebral number in fishes". Journal of Biogeography. 35 (3): 501–508. doi:10.1111/j.1365-2699.2007.01823.x.

[2] Jordan, David Starr (1908-02-01). "The Law of Geminate Species". The American Naturalist. 42 (494): 73–80. doi:10.1086/278905. ISSN 0003-0147.

[3] Fitzpatrick, Benjamin M.; Turelli, Michael (2006). "The Geography of Mammalian Speciation: Mixed Signals from Phylogenies and Range Maps". Evolution. 60 (3): 601–615. doi:10.1111/j.0014-3820.2006.tb01140.x. ISSN 1558-5646. PMID 16637504. S2CID 32663278.

[4] Mayr, Ernst, 1904-2005. (1963). Animal species and evolution. Cambridge: Belknap Press of Harvard University Press. ISBN 0-674-03750-2. OCLC 551391.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)

[5] Barraclough, Timothy G. (20 June 2019). The evolutionary biology of species (First ed.). Oxford. ISBN 978-0-19-106665-8. OCLC 1104724041.{{cite book}}: CS1 maint: location missing publisher (link)

[6] Jordan, David Starr (February 1908). "The Law of Geminate Species". The American Naturalist. 42 (494): 73–80. doi:10.1086/278905. ISSN 0003-0147.

[7] Allen, J. A. (October 1907). "Mutations and the Geographic Distribution of Nearly Related Species in Plants and Animals". The American Naturalist. 41 (490): 653–655. doi:10.1086/278852. ISSN 0003-0147.

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v t e Biological rules
Rules	Allen's rule Shorter appendages in colder climates Bateson's rule Extra limbs mirror their neighbours Bergmann's rule Larger bodies in colder climates Cope's rule Bodies get larger over time Deep-sea gigantism Larger bodies in deep-sea animals Dollo's law Loss of complex traits is irreversible Eichler's rule Parasites co-vary with their hosts Emery's rule Insect social parasites are often in same genus as their hosts Fahrenholz's rule Host and parasite phylogenies become congruent Foster's rule (Insular gigantism, Insular dwarfism) Small species get larger, large species smaller, after colonizing islands Gause's law Complete competitors cannot coexist Gloger's rule Lighter coloration in colder, drier climates Haldane's rule Hybrid sexes that are absent, rare, or sterile, are heterogamic Harrison's rule Parasites co-vary in size with their hosts Hamilton's rule Genes increase in frequency when relatedness of recipient to actor times benefit to recipient exceeds reproductive cost to actor Kleiber's law An animals metabolic rate decreases with its size Hennig's progression rule In cladistics, the most primitive species are found in earliest, central, part of group's area Jarman–Bell principle The correlation between the size of an animal and its diet quality; larger animals can consume lower quality diet Jordan's rule Inverse relationship between water temperature and no. of fin rays, vertebrae Lack's principle Birds lay only as many eggs as they can provide food for Rapoport's rule Latitudinal range increases with latitude Rensch's rule Sexual size dimorphism increases with size when males are larger, decreases with size when females are larger Rosa's rule Groups evolve from character variation in primitive species to a fixed character state in advanced ones Schmalhausen's law A population at limit of tolerance in one aspect is vulnerable to small differences in any other aspect Thayer's law The top of an animals coloration is darker than the bottom Thorson's rule No. of eggs of benthic marine invertebrates decreases with latitude Van Valen's law Probability of extinction of a group is constant over time von Baer's laws Embryos start from a common form and develop into increasingly specialised forms Williston's law Parts in an organism become reduced in number and specialized in function
Related	Countergradient variation Where genetics opposes environment as a factor Gigantothermy Large ectothermic animals more easily maintain constant body temperature

See also

References