Eichler's rule is one of several coevolutionary rules which states that

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s 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 Parasitology is the study of parasites, their host (biology), hosts, and the relationship between them. As a List of biology disciplines, biological discipline, the scope of parasitology is not determined by the organism or environment in questio ...

who served as a professor of parasitology at

Leipzig University Leipzig University (), in Leipzig in Saxony, Germany, is one of the world's oldest universities and the second-oldest university (by consecutive years of existence) in Germany. The university was founded on 2 December 1409 by Frederick I, Electo ...

. 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.

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 Louse (: lice) is the common name for any member of the infraorder Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera was previously recognized as an order, until a 2021 genetic study determined th ...

. 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.

References

{{Biological rules Parasitology Lice Biodiversity Evolutionary biology