Generalized principle to describe patterns observed in living organisms
A biological rule or biological law is a generalized
law,
principle, or
rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the
ecology and
biogeographical distributions of plant and animal
species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them.[1][2]
From the birth of their science, biologists have sought to explain apparent regularities in observational data. In
his biology,
Aristotle inferred rules governing differences between live-bearing
tetrapods (in modern terms, terrestrial placental
mammals). Among his rules were that
brood size decreases with adult body mass, while
lifespan increases with
gestation period and with body mass, and
fecundity decreases with lifespan. Thus, for example, elephants have smaller and fewer broods than mice, but longer lifespan and gestation.[3] Rules like these concisely organized the sum of knowledge obtained by early scientific measurements of the natural world, and could be used as
models to predict future observations. Among the earliest biological rules in modern times are those of
Karl Ernst von Baer (from 1828 onwards) on
embryonic development,[4] and of
Constantin Wilhelm Lambert Gloger on animal pigmentation, in 1833.[5]
There is some
scepticism among biogeographers about the usefulness of general rules. For example, J.C. Briggs, in his 1987 book Biogeography and Plate Tectonics, comments that while
Willi Hennig's rules on
cladistics "have generally been helpful", his progression rule is "suspect".[6]
List of biological rules
Allen's rule states that the body shapes and proportions of endotherms vary by climatic temperature by either minimizing exposed surface area to minimize heat loss in cold climates or maximizing exposed surface area to maximize heat loss in hot climates. It is named after
Joel Asaph Allen who described it in 1877.[8][9]
Bateson's rule states that extra legs are mirror-symmetric with their neighbours, such as when an extra leg appears in an insect's leg socket. It is named after the pioneering geneticist
William Bateson who observed it in 1894. It appears to be caused by the leaking of positional signals across the limb-limb interface, so that the extra limb's polarity is reversed.[10]
Bergmann's rule states that within a broadly distributed taxonomic
clade, populations and species of larger size are found in colder environments, and species of smaller size are found in warmer regions. It applies with exceptions to many mammals and birds. It was named after
Carl Bergmann who described it in 1847.[11][12][13][14][15]
Deep-sea gigantism, noted in 1880 by
Henry Nottidge Moseley,[18] states that deep-sea animals are larger than their shallow-water counterparts. In the case of marine
crustaceans, it has been proposed that the increase in size with depth occurs for the same reason as the increase in size with
latitude (Bergmann's rule): both trends involve increasing size with decreasing temperature.[12]
Dollo's law of irreversibility, proposed in 1893[19] by
French-born
BelgianpaleontologistLouis Dollo states that "an organism never returns exactly to a former state, even if it finds itself placed in conditions of existence identical to those in which it has previously lived ... it always keeps some trace of the intermediate stages through which it has passed."[20][21][22]
Eichler's rule states that the taxonomic diversity of parasites co-varies with the diversity of their hosts. It was observed in 1942 by Wolfdietrich Eichler, and is named for him.[23][24][25]
Foster's rule, the island rule, or the island effect states that members of a species get smaller or bigger depending on the resources available in the environment.[28][29][30] The rule was first stated by
J. Bristol Foster in 1964 in the journal Nature, in an article titled "The evolution of mammals on islands".[31]
Gause's law or the competitive exclusion principle, named for
Georgy Gause, states that two species competing for the same resource cannot coexist at constant population values. The competition leads either to the extinction of the weaker competitor or to an
evolutionary or behavioral shift toward a different
ecological niche.[32]
Hamilton's rule states that
genes should increase in frequency when the relatedness of a recipient to an actor, multiplied by the benefit to the recipient, exceeds the reproductive cost to the actor. This is a prediction from the theory of
kin selection formulated by
W. D. Hamilton.[35]
Harrison's rule states that parasite body sizes co-vary with those of their hosts. He proposed the rule for
lice,[36] but later authors have shown that it works equally well for many other groups of parasite including barnacles, nematodes,[37][38] fleas, flies, mites, and ticks, and for the analogous case of small herbivores on large plants.[39][40][41]
Hennig's progression rule states that when considering a group of species in
cladistics, the species with the most primitive characters are found within the earliest part of the area, which will be the center of origin of that group. It is named for
Willi Hennig, who devised the rule.[6][42]
Lack's principle, proposed by
David Lack, states that "the clutch size of each species of bird has been adapted by
natural selection to correspond with the largest number of young for which the parents can, on average, provide enough food".[44]
Rensch's rule states that, across animal species within a lineage,
sexual size dimorphism increases with body size when the male is the larger sex, and decreases as body size increases when the female is the larger sex. The rule applies in
primates,
pinnipeds (seals), and
even-toed ungulates (such as cattle and deer).[46] It is named after
Bernhard Rensch, who proposed it in 1950.[47]
Schmalhausen's law, named after
Ivan Schmalhausen, states that a
population at the extreme limit of its tolerance in any one aspect is more vulnerable to small differences in any other aspect. Therefore, the variance of data is not simply noise interfering with the detection of so-called "main effects", but also an indicator of stressful conditions leading to greater vulnerability.[48]
Thorson's rule states that
benthicmarine invertebrates at low latitudes tend to produce large numbers of eggs developing to
pelagic (often planktotrophic [plankton-feeding]) and widely dispersing larvae, whereas at high latitudes such organisms tend to produce fewer and larger lecithotrophic (yolk-feeding) eggs and larger offspring, often by
viviparity or
ovoviviparity, which are often brooded.[49] It was named after
Gunnar Thorson by S. A. Mileikovsky in 1971.[50]
Williston's law states that in lineages such as the
arthropods, limbs tend to become fewer and more specialised, as shown by the
crayfish (right), whereas the more basal
trilobites had many similar legs.
Van Valen's law states that the probability of
extinction for species and higher taxa (such as families and orders) is constant for each group over time; groups grow neither more resistant nor more vulnerable to extinction, however old their lineage is. It is named for the evolutionary biologist
Leigh Van Valen.[51]
von Baer's laws, discovered by
Karl Ernst von Baer, state that
embryos start from a common form and develop into increasingly specialised forms, so that the diversification of embryonic form mirrors the
taxonomic and phylogenetic tree. Therefore, all animals in a phylum share a similar early embryo; animals in smaller taxa (classes, orders, families, genera, species) share later and later embryonic stages. This was in sharp contrast to the
recapitulation theory of
Johann Friedrich Meckel (and later of
Ernst Haeckel), which claimed that embryos went through stages resembling adult organisms from successive stages of the scala naturae from supposedly lowest to highest levels of organisation.[52][53][4]
Williston's law, first noticed by
Samuel Wendell Williston, states that parts in an organism tend to become reduced in number and greatly specialized in function. He had studied the dentition of vertebrates, and noted that where ancient animals had mouths with differing kinds of teeth, modern carnivores had incisors and canines specialized for tearing and cutting flesh, while modern herbivores had large molars specialized for grinding tough plant materials.[54]
^Jørgensen, Sven Erik (2002). "Explanation of ecological rules and observation by application of ecosystem theory and ecological models". Ecological Modelling. 158 (3): 241–248.
Bibcode:
2002EcMod.158..241J.
doi:
10.1016/S0304-3800(02)00236-3.
^
abTimofeev, S. F. (2001). "Bergmann's Principle and Deep-Water Gigantism in Marine Crustaceans". Biology Bulletin of the Russian Academy of Sciences. 28 (6): 646–650.
doi:
10.1023/A:1012336823275.
S2CID28016098.
^Klassen, G. J. (1992). "Coevolution: a history of the macroevolutionary approach to studying host-parasite associations". Journal of Parasitology. 78 (4): 573–87.
doi:
10.2307/3283532.
JSTOR3283532.
PMID1635016.
^Richard Deslippe (2010).
"Social Parasitism in Ants". Nature Education Knowledge. Retrieved 2010-10-29. In 1909, the taxonomist Carlo Emery made an important generalization, now known as Emery's rule, which states that social parasites and their hosts share common ancestry and hence are closely related to each other (Emery 1909).
^Emery, Carlo (1909). "Über den Ursprung der dulotischen, parasitischen und myrmekophilen Ameisen". Biologisches Centralblatt (in German). 29: 352–362.
^Juan Luis Arsuaga, Andy Klatt, The Neanderthal's Necklace: In Search of the First Thinkers, Thunder's Mouth Press, 2004,
ISBN1-56858-303-6,
ISBN978-1-56858-303-7, p. 199.
^Lomolino, Mark V. (February 1985). "Body Size of Mammals on Islands: The Island Rule Reexamined". The American Naturalist. 125 (2): 310–316.
doi:
10.1086/284343.
JSTOR2461638.
S2CID84642837.
^Stevens, G. C. (1989). "The latitudinal gradients in geographical range: how so many species co-exist in the tropics". American Naturalist. 133 (2): 240–256.
doi:
10.1086/284913.
S2CID84158740.
^Fairbairn, D.J. (1997). "Allometry for Sexual Size Dimorphism: Pattern and Process in the Coevolution of Body Size in Males and Females". Annu. Rev. Ecol. Syst. 28 (1): 659–687.
doi:
10.1146/annurev.ecolsys.28.1.659.
^Rensch, Bernhard (1950). "Die Abhängigkeit der relativen Sexualdifferenz von der Körpergrösse". Bonner Zoologische Beiträge. 1: 58–69.
^Thorson, G. 1957 Bottom communities (sublittoral or shallow shelf). In "Treatise on Marine Ecology and Palaeoecology" (Ed J.W. Hedgpeth) pp. 461-534. Geological Society of America.
^Mileikovsky, S. A. 1971. Types of larval development in marine bottom invertebrates, their distribution and ecological significance: a reevaluation. Marine Biology 19: 193-213
^Opitz, John M.; Schultka, Rüdiger; Göbbel, Luminita (2006). "Meckel on developmental pathology". American Journal of Medical Genetics Part A. 140A (2): 115–128.
doi:
10.1002/ajmg.a.31043.
PMID16353245.
S2CID30513424.
Generalized principle to describe patterns observed in living organisms
A biological rule or biological law is a generalized
law,
principle, or
rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the
ecology and
biogeographical distributions of plant and animal
species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them.[1][2]
From the birth of their science, biologists have sought to explain apparent regularities in observational data. In
his biology,
Aristotle inferred rules governing differences between live-bearing
tetrapods (in modern terms, terrestrial placental
mammals). Among his rules were that
brood size decreases with adult body mass, while
lifespan increases with
gestation period and with body mass, and
fecundity decreases with lifespan. Thus, for example, elephants have smaller and fewer broods than mice, but longer lifespan and gestation.[3] Rules like these concisely organized the sum of knowledge obtained by early scientific measurements of the natural world, and could be used as
models to predict future observations. Among the earliest biological rules in modern times are those of
Karl Ernst von Baer (from 1828 onwards) on
embryonic development,[4] and of
Constantin Wilhelm Lambert Gloger on animal pigmentation, in 1833.[5]
There is some
scepticism among biogeographers about the usefulness of general rules. For example, J.C. Briggs, in his 1987 book Biogeography and Plate Tectonics, comments that while
Willi Hennig's rules on
cladistics "have generally been helpful", his progression rule is "suspect".[6]
List of biological rules
Allen's rule states that the body shapes and proportions of endotherms vary by climatic temperature by either minimizing exposed surface area to minimize heat loss in cold climates or maximizing exposed surface area to maximize heat loss in hot climates. It is named after
Joel Asaph Allen who described it in 1877.[8][9]
Bateson's rule states that extra legs are mirror-symmetric with their neighbours, such as when an extra leg appears in an insect's leg socket. It is named after the pioneering geneticist
William Bateson who observed it in 1894. It appears to be caused by the leaking of positional signals across the limb-limb interface, so that the extra limb's polarity is reversed.[10]
Bergmann's rule states that within a broadly distributed taxonomic
clade, populations and species of larger size are found in colder environments, and species of smaller size are found in warmer regions. It applies with exceptions to many mammals and birds. It was named after
Carl Bergmann who described it in 1847.[11][12][13][14][15]
Deep-sea gigantism, noted in 1880 by
Henry Nottidge Moseley,[18] states that deep-sea animals are larger than their shallow-water counterparts. In the case of marine
crustaceans, it has been proposed that the increase in size with depth occurs for the same reason as the increase in size with
latitude (Bergmann's rule): both trends involve increasing size with decreasing temperature.[12]
Dollo's law of irreversibility, proposed in 1893[19] by
French-born
BelgianpaleontologistLouis Dollo states that "an organism never returns exactly to a former state, even if it finds itself placed in conditions of existence identical to those in which it has previously lived ... it always keeps some trace of the intermediate stages through which it has passed."[20][21][22]
Eichler's rule states that the taxonomic diversity of parasites co-varies with the diversity of their hosts. It was observed in 1942 by Wolfdietrich Eichler, and is named for him.[23][24][25]
Foster's rule, the island rule, or the island effect states that members of a species get smaller or bigger depending on the resources available in the environment.[28][29][30] The rule was first stated by
J. Bristol Foster in 1964 in the journal Nature, in an article titled "The evolution of mammals on islands".[31]
Gause's law or the competitive exclusion principle, named for
Georgy Gause, states that two species competing for the same resource cannot coexist at constant population values. The competition leads either to the extinction of the weaker competitor or to an
evolutionary or behavioral shift toward a different
ecological niche.[32]
Hamilton's rule states that
genes should increase in frequency when the relatedness of a recipient to an actor, multiplied by the benefit to the recipient, exceeds the reproductive cost to the actor. This is a prediction from the theory of
kin selection formulated by
W. D. Hamilton.[35]
Harrison's rule states that parasite body sizes co-vary with those of their hosts. He proposed the rule for
lice,[36] but later authors have shown that it works equally well for many other groups of parasite including barnacles, nematodes,[37][38] fleas, flies, mites, and ticks, and for the analogous case of small herbivores on large plants.[39][40][41]
Hennig's progression rule states that when considering a group of species in
cladistics, the species with the most primitive characters are found within the earliest part of the area, which will be the center of origin of that group. It is named for
Willi Hennig, who devised the rule.[6][42]
Lack's principle, proposed by
David Lack, states that "the clutch size of each species of bird has been adapted by
natural selection to correspond with the largest number of young for which the parents can, on average, provide enough food".[44]
Rensch's rule states that, across animal species within a lineage,
sexual size dimorphism increases with body size when the male is the larger sex, and decreases as body size increases when the female is the larger sex. The rule applies in
primates,
pinnipeds (seals), and
even-toed ungulates (such as cattle and deer).[46] It is named after
Bernhard Rensch, who proposed it in 1950.[47]
Schmalhausen's law, named after
Ivan Schmalhausen, states that a
population at the extreme limit of its tolerance in any one aspect is more vulnerable to small differences in any other aspect. Therefore, the variance of data is not simply noise interfering with the detection of so-called "main effects", but also an indicator of stressful conditions leading to greater vulnerability.[48]
Thorson's rule states that
benthicmarine invertebrates at low latitudes tend to produce large numbers of eggs developing to
pelagic (often planktotrophic [plankton-feeding]) and widely dispersing larvae, whereas at high latitudes such organisms tend to produce fewer and larger lecithotrophic (yolk-feeding) eggs and larger offspring, often by
viviparity or
ovoviviparity, which are often brooded.[49] It was named after
Gunnar Thorson by S. A. Mileikovsky in 1971.[50]
Williston's law states that in lineages such as the
arthropods, limbs tend to become fewer and more specialised, as shown by the
crayfish (right), whereas the more basal
trilobites had many similar legs.
Van Valen's law states that the probability of
extinction for species and higher taxa (such as families and orders) is constant for each group over time; groups grow neither more resistant nor more vulnerable to extinction, however old their lineage is. It is named for the evolutionary biologist
Leigh Van Valen.[51]
von Baer's laws, discovered by
Karl Ernst von Baer, state that
embryos start from a common form and develop into increasingly specialised forms, so that the diversification of embryonic form mirrors the
taxonomic and phylogenetic tree. Therefore, all animals in a phylum share a similar early embryo; animals in smaller taxa (classes, orders, families, genera, species) share later and later embryonic stages. This was in sharp contrast to the
recapitulation theory of
Johann Friedrich Meckel (and later of
Ernst Haeckel), which claimed that embryos went through stages resembling adult organisms from successive stages of the scala naturae from supposedly lowest to highest levels of organisation.[52][53][4]
Williston's law, first noticed by
Samuel Wendell Williston, states that parts in an organism tend to become reduced in number and greatly specialized in function. He had studied the dentition of vertebrates, and noted that where ancient animals had mouths with differing kinds of teeth, modern carnivores had incisors and canines specialized for tearing and cutting flesh, while modern herbivores had large molars specialized for grinding tough plant materials.[54]
^Jørgensen, Sven Erik (2002). "Explanation of ecological rules and observation by application of ecosystem theory and ecological models". Ecological Modelling. 158 (3): 241–248.
Bibcode:
2002EcMod.158..241J.
doi:
10.1016/S0304-3800(02)00236-3.
^
abTimofeev, S. F. (2001). "Bergmann's Principle and Deep-Water Gigantism in Marine Crustaceans". Biology Bulletin of the Russian Academy of Sciences. 28 (6): 646–650.
doi:
10.1023/A:1012336823275.
S2CID28016098.
^Klassen, G. J. (1992). "Coevolution: a history of the macroevolutionary approach to studying host-parasite associations". Journal of Parasitology. 78 (4): 573–87.
doi:
10.2307/3283532.
JSTOR3283532.
PMID1635016.
^Richard Deslippe (2010).
"Social Parasitism in Ants". Nature Education Knowledge. Retrieved 2010-10-29. In 1909, the taxonomist Carlo Emery made an important generalization, now known as Emery's rule, which states that social parasites and their hosts share common ancestry and hence are closely related to each other (Emery 1909).
^Emery, Carlo (1909). "Über den Ursprung der dulotischen, parasitischen und myrmekophilen Ameisen". Biologisches Centralblatt (in German). 29: 352–362.
^Juan Luis Arsuaga, Andy Klatt, The Neanderthal's Necklace: In Search of the First Thinkers, Thunder's Mouth Press, 2004,
ISBN1-56858-303-6,
ISBN978-1-56858-303-7, p. 199.
^Lomolino, Mark V. (February 1985). "Body Size of Mammals on Islands: The Island Rule Reexamined". The American Naturalist. 125 (2): 310–316.
doi:
10.1086/284343.
JSTOR2461638.
S2CID84642837.
^Stevens, G. C. (1989). "The latitudinal gradients in geographical range: how so many species co-exist in the tropics". American Naturalist. 133 (2): 240–256.
doi:
10.1086/284913.
S2CID84158740.
^Fairbairn, D.J. (1997). "Allometry for Sexual Size Dimorphism: Pattern and Process in the Coevolution of Body Size in Males and Females". Annu. Rev. Ecol. Syst. 28 (1): 659–687.
doi:
10.1146/annurev.ecolsys.28.1.659.
^Rensch, Bernhard (1950). "Die Abhängigkeit der relativen Sexualdifferenz von der Körpergrösse". Bonner Zoologische Beiträge. 1: 58–69.
^Thorson, G. 1957 Bottom communities (sublittoral or shallow shelf). In "Treatise on Marine Ecology and Palaeoecology" (Ed J.W. Hedgpeth) pp. 461-534. Geological Society of America.
^Mileikovsky, S. A. 1971. Types of larval development in marine bottom invertebrates, their distribution and ecological significance: a reevaluation. Marine Biology 19: 193-213
^Opitz, John M.; Schultka, Rüdiger; Göbbel, Luminita (2006). "Meckel on developmental pathology". American Journal of Medical Genetics Part A. 140A (2): 115–128.
doi:
10.1002/ajmg.a.31043.
PMID16353245.
S2CID30513424.