Eichler's rule

When comparing host sister clades we tend to find taxonomically richer parasite fauna on the taxonomically richer group of hosts.

Eichler's rule is one of several coevolutionary rules which states that parasites tend to be highly specific to their hosts, and thus it seems reasonable to expect a positive co-variation between the taxonomic richness of hosts and that of their parasites.

History

A rule to describe the taxonomic relationship between parasites and their hosts was developed in 1942 by Wolfdietrich Eichler (1912–1994), a German authority in zoology and parasitology who served as a professor of parasitology at Leipzig University.^[1]^[2] The principle was later dubbed 'Eichler's rule'. It is one of the first three coevolutionary rules, created in opposition to Heinrich Fahrenholz's research into coevolution.^[3]

Research

As a part of their 2012 study, Vas and his co-authors tested Eichler's rule, and concluded that exceptionally strong correlational evidence supports the positive co-variation between the species richness of avian and mammalian families and the generic richness of their parasitic lice.^[4]

In volume nine of Advances in Parasitology, parasitologist W. Grant Inglis posited that, when studying the co-variation between the taxonomic richness of hosts and parasites, it is easier to study parasites than free-living host organisms.^[5]

References

^ Eichler, Wolfdietrich (1966). "Two New Evolutionary Terms for Speciation in Parasitic Animals". Systematic Zoology. 15 (3): 216–218. doi:10.2307/2411393. ISSN 0039-7989. JSTOR 2411393. PMID 5924358.
^ Eichler, W. (1942). "Die Entfaltungsregel und andere Gesetzmäßigkeiten in den parasitogenetischen Beziehungen der Mallophagen und anderer ständiger Parasiten zu ihren Wirten" (PDF). Zoologischer Anzeiger. 136: 77–83. Archived from the original (PDF) on 2017-03-04. Retrieved 2012-12-28.
^ Klassen, G. J. (1992). "Coevolution: a history of the macroevolutionary approach to studying host-parasite associations". The Journal of Parasitology. 78 (4): 573–587. doi:10.2307/3283532. JSTOR 3283532. PMID 1635016.
^ Vas, Z.; Csorba, G.; Rozsa, L. (2012). "Evolutionary co-variation of host and parasite diversity – the first test of Eichler's rule using parasitic lice (Insecta: Phthiraptera)" (PDF). Parasitology Research. 111 (1): 393–401. doi:10.1007/s00436-012-2850-9. PMID 22350674. S2CID 14923342.
^ Advances in Parasitology. Academic Press. 1971-03-31. ISBN 978-0-08-058055-5.

[1] Eichler, Wolfdietrich (1966). "Two New Evolutionary Terms for Speciation in Parasitic Animals". Systematic Zoology. 15 (3): 216–218. doi:10.2307/2411393. ISSN 0039-7989. JSTOR 2411393. PMID 5924358.

[Eichler_1942-2] Eichler, W. (1942). "Die Entfaltungsregel und andere Gesetzmäßigkeiten in den parasitogenetischen Beziehungen der Mallophagen und anderer ständiger Parasiten zu ihren Wirten" (PDF). Zoologischer Anzeiger. 136: 77–83. Archived from the original (PDF) on 2017-03-04. Retrieved 2012-12-28.

[Klassen-3] Klassen, G. J. (1992). "Coevolution: a history of the macroevolutionary approach to studying host-parasite associations". The Journal of Parasitology. 78 (4): 573–587. doi:10.2307/3283532. JSTOR 3283532. PMID 1635016.

[Vas-4] Vas, Z.; Csorba, G.; Rozsa, L. (2012). "Evolutionary co-variation of host and parasite diversity – the first test of Eichler's rule using parasitic lice (Insecta: Phthiraptera)" (PDF). Parasitology Research. 111 (1): 393–401. doi:10.1007/s00436-012-2850-9. PMID 22350674. S2CID 14923342.

[5] Advances in Parasitology. Academic Press. 1971-03-31. ISBN 978-0-08-058055-5.

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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