Harrison's rule

Harrison's rule is an observation in evolutionary biology by Launcelot Harrison which states that in comparisons across closely related species, host and parasite body sizes tend to covary positively.

Parasite species' body size increases with host species' body size

Launcelot Harrison, an Australian authority in zoology and parasitology, published a study in 1915 concluding that host and parasite body sizes tend to covary positively,^[1] a covariation later dubbed as 'Harrison's rule'. Harrison himself originally proposed it to interpret the variability of congeneric louse species. However, subsequent authors verified it for a wide variety of parasitic organisms including nematodes,^[2]^[3]^[4]^[5] rhizocephalan barnacles,^[6] fleas, lice, ticks, parasitic flies and mites, as well as herbivorous insects associated with specific host plants.^[3]^[7]^[8]

The variability of parasite species' body size increases with host species' body size

Robert Poulin observed that in comparisons across species, the variability of parasite body size also increases with host body size.^[9] It is self-evident that we expect greater variation coming together with greater mean body sizes due to an allometric power law scaling effect.^[10] However, Poulin referred to parasites' increasing body size variability due to biological reasons, thus we expect an increase greater than that caused by a scaling effect.

Recently, Harnos et al. applied phylogenetically controlled statistical methods to test Harrison's rule and Poulin's s Increasing Variance Hypothesis in avian lice.^[11] Their results indicate that the three major families of avian lice (Ricinidae, Menoponidae, Philopteridae) follow Harrison's rule, and two of them (Menoponidae, Philopteridae) also follow Poulin's supplement to it.

Implications

The allometry between host and parasite body sizes constitutes an evident aspect of host–parasite coevolution. The slope of this relationship is a taxon-specific character. Parasites' body size is known to covary positively with fecundity^[12] and thus it likely affects the virulence of parasitic infections as well.

References

^ Harrison, Launcelot (1915). "Mallophaga from Apteryx, and their significance; with a note on the genus Rallicola" (PDF). Parasitology. 8: 88–100. doi:10.1017/S0031182000010428. Archived from the original (PDF) on 2017-11-07. Retrieved 2018-03-30.
^ Kirchner, TB; Anderson, RV; Ingham, RE (1980). "Natural selection and the distribution of nematode sizes". Ecology. 61 (2): 232–237. doi:10.2307/1935179. JSTOR 1935179.
^ ^a ^b Harvey, PH; Keymer, AE (1991). "Comparing life histories using phylogenies". Philosophical Transactions of the Royal Society B. 332 (1262): 31–39. Bibcode:1991RSPTB.332...31H. doi:10.1098/rstb.1991.0030.
^ Morand, S; Legendre, P; Gardner, SL; Hugot, JP (1996). "Body size evolution of oxyurid (Nematoda) parasites: the role of hosts". Oecologia. 107 (2): 274–282. Bibcode:1996Oecol.107..274M. doi:10.1007/BF00327912. PMID 28307314. S2CID 13512689.
^ Morand, S; Sorci, G (1998). "Determinants of life-history evolution in nematodes". Parasitology Today. 14 (5): 193–196. doi:10.1016/S0169-4758(98)01223-X. PMID 17040750.
^ Poulin, R; Hamilton, WJ (1997). "Ecological correlates of body size and egg size in parasitic Ascothoracida and Rhizocephala (Crustacea)". Acta Oecologica. 18 (6): 621–635. Bibcode:1997AcO....18..621P. doi:10.1016/S1146-609X(97)80047-1.
^ Morand, S; Hafner, MS; Page, RDM; Reed, DL (2000). "Comparative body size relationships in pocket gophers and their chewing lice". Zoological Journal of the Linnean Society. 70 (2): 239–249. doi:10.1111/j.1095-8312.2000.tb00209.x.
^ Johnson, KP; Bush, SE; Clayton, DH (2005). "Correlated evolution of host and parasite body size: tests of Harrison's rule using birds and lice". Evolution. 59 (8): 1744–1753. doi:10.1111/j.0014-3820.2005.tb01823.x. PMID 16329244. S2CID 8501561.
^ Poulin, R (2006). Evolutionary ecology of parasites. Princeton University Press. ISBN 9780691120850.
^ Xiao, X; White, EP; Hooten, MB; Durham, SL (2011). "On the use of log-transformation vs. nonlinear regression for analyzing biological power-laws". Ecology. 92 (10): 1887–1894. doi:10.1890/11-0538.1. PMID 22073779.
^ Harnos, A; Lang, Z; Petras, D; Bush, SE; Szabo, K; Rozsa, L (2017). "Size matters for lice on birds: coevolutionary allometry of host and parasite body size" (PDF). Evolution. 92 (2): 1887–1894. doi:10.1111/evo.13147. PMID 27925167. S2CID 4701333.
^ Villa, SM; Evans, MD; Subhani, YK; Altuna, JC; Bush, SE; Clayton, DH (2018). "Body size and fecundity are correlated in feather lice (Phthiraptera: Ischnocera): implications for Harrison's rule". Ecological Entomology. 43 (3): 394–396. doi:10.1111/een.12511.

[Harrison_1915-1] Harrison, Launcelot (1915). "Mallophaga from Apteryx, and their significance; with a note on the genus Rallicola" (PDF). Parasitology. 8: 88–100. doi:10.1017/S0031182000010428. Archived from the original (PDF) on 2017-11-07. Retrieved 2018-03-30.

[2] Kirchner, TB; Anderson, RV; Ingham, RE (1980). "Natural selection and the distribution of nematode sizes". Ecology. 61 (2): 232–237. doi:10.2307/1935179. JSTOR 1935179.

[Harveyetal-3] Harvey, PH; Keymer, AE (1991). "Comparing life histories using phylogenies". Philosophical Transactions of the Royal Society B. 332 (1262): 31–39. Bibcode:1991RSPTB.332...31H. doi:10.1098/rstb.1991.0030.

[4] Morand, S; Legendre, P; Gardner, SL; Hugot, JP (1996). "Body size evolution of oxyurid (Nematoda) parasites: the role of hosts". Oecologia. 107 (2): 274–282. Bibcode:1996Oecol.107..274M. doi:10.1007/BF00327912. PMID 28307314. S2CID 13512689.

[5] Morand, S; Sorci, G (1998). "Determinants of life-history evolution in nematodes". Parasitology Today. 14 (5): 193–196. doi:10.1016/S0169-4758(98)01223-X. PMID 17040750.

[6] Poulin, R; Hamilton, WJ (1997). "Ecological correlates of body size and egg size in parasitic Ascothoracida and Rhizocephala (Crustacea)". Acta Oecologica. 18 (6): 621–635. Bibcode:1997AcO....18..621P. doi:10.1016/S1146-609X(97)80047-1.

[7] Morand, S; Hafner, MS; Page, RDM; Reed, DL (2000). "Comparative body size relationships in pocket gophers and their chewing lice". Zoological Journal of the Linnean Society. 70 (2): 239–249. doi:10.1111/j.1095-8312.2000.tb00209.x.

[8] Johnson, KP; Bush, SE; Clayton, DH (2005). "Correlated evolution of host and parasite body size: tests of Harrison's rule using birds and lice". Evolution. 59 (8): 1744–1753. doi:10.1111/j.0014-3820.2005.tb01823.x. PMID 16329244. S2CID 8501561.

[9] Poulin, R (2006). Evolutionary ecology of parasites. Princeton University Press. ISBN 9780691120850.

[10] Xiao, X; White, EP; Hooten, MB; Durham, SL (2011). "On the use of log-transformation vs. nonlinear regression for analyzing biological power-laws". Ecology. 92 (10): 1887–1894. doi:10.1890/11-0538.1. PMID 22073779.

[11] Harnos, A; Lang, Z; Petras, D; Bush, SE; Szabo, K; Rozsa, L (2017). "Size matters for lice on birds: coevolutionary allometry of host and parasite body size" (PDF). Evolution. 92 (2): 1887–1894. doi:10.1111/evo.13147. PMID 27925167. S2CID 4701333.

[12] Villa, SM; Evans, MD; Subhani, YK; Altuna, JC; Bush, SE; Clayton, DH (2018). "Body size and fecundity are correlated in feather lice (Phthiraptera: Ischnocera): implications for Harrison's rule". Ecological Entomology. 43 (3): 394–396. doi:10.1111/een.12511.

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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