Biological rules

Biological rules offer general principles or patterns in biology, often derived from observations across various organisms, conditions, or time periods. They serve as guides or heuristic devices to understand biological phenomena and patterns in the vast diversity of life. Here are some of the most notable rules and their explanations:

Allen's Rule

Allen's rule postulates that animals in colder climates will often have shorter appendages compared to their counterparts in warmer climates. This rule is thought to help reduce heat loss.

Bateson's Rule

According to Bateson's rule, extra or supernumerary limbs will often mirror their opposite counterparts. For example, a mutation leading to an extra limb will result in that limb's structure resembling its neighbor.

Bergmann's Rule

Bergmann's rule is illustrated with a map and graph, suggesting that animals in colder climates are generally larger than similar species in warmer regions. The larger body mass is believed to help conserve body heat.

Cope's Rule

Cope's rule posits that the body size of species tends to increase over evolutionary time. However, it's worth noting that this isn't universal across all lineages.

Deep-sea Gigantism

In the mysterious world of the deep sea, there's a trend known as Deep-sea gigantism. Creatures here tend to be much larger than their shallow-water relatives. The reasons for this phenomenon remain a topic of research.

Dollo's Law

According to Dollo's law, complex traits that are lost during evolution cannot be regained. In other words, once a specific evolutionary pathway is traversed, it can't be reversed.

Eichler's Rule

Eichler's rule states that parasites will co-vary with their hosts. If a host evolves or changes over time, its parasites are likely to evolve in tandem.

Emery's Rule

In the realm of insects, Emery's rule indicates that social parasites are often in the same genus as their hosts.

Fahrenholz's Rule

A refinement of the co-evolution concept, Fahrenholz's rule asserts that host and parasite phylogenies become congruent or mirror each other over time.

Foster's Rule

Also known as insular gigantism and Insular dwarfism, Foster's rule explains that after colonizing islands, small species often become larger while large species become smaller. This phenomenon results from the unique ecological pressures on islands.

Gause's Law

Based on the principle of competitive exclusion, Gause's law posits that two species competing for the exact same resources cannot coexist indefinitely.

Gloger's Rule

Gloger's rule states that animals in colder, drier climates often have lighter coloration than those in warmer, moist climates.

Haldane's Rule

Haldane's rule touches on genetics and hybridization. In hybrid offspring, the sex that is absent, rare, or sterile will be the heterogamic one (i.e., the one with two different sex chromosomes).

Harrison's Rule

A continuation on the theme of hosts and parasites, Harrison's rule asserts that the size of parasites will co-vary with the size of their hosts.

Hamilton's Rule

Delving into the realm of social behavior and genetics, Hamilton's rule states that genes will increase in frequency when the relatedness of the recipient to the actor times the benefit to the recipient is greater than the reproductive cost to the actor.

Kleiber's Law

Kleiber's law touches on the fascinating relationship between body size and metabolism. As an animal's size increases, its metabolic rate tends to decrease proportionally.

Jarman–Bell Principle

The Jarman–Bell principle highlights a relationship between animal size and diet quality. Larger animals can often subsist on a lower quality diet compared to smaller animals.

Hennig's Progression Rule

Hennig's progression rule in cladistics posits that the most primitive or ancestral species within a particular group are often found in the earliest, central part of that group's geographical distribution. As evolution progresses, newer or derived species tend to appear in peripheral areas.

Jordan's Rule

Jordan's rule highlights an intriguing pattern in marine biology. There's an inverse relationship between water temperature and the number of fin rays and vertebrae in fish. Typically, fish in colder waters have more fin rays and vertebrae than those in warmer waters.

Lack's Principle

In the realm of ornithology, Lack's principle suggests that birds lay only as many eggs as they can procure food for. This strategy ensures optimal survival rates for the offspring.

Rapoport's Rule

Rapoport's rule denotes a latitudinal pattern in species distribution. As one moves from the equator towards the poles, species tend to occupy broader latitudinal ranges.

Rensch's Rule

When considering sexual dimorphism, Rensch's rule states that sexual size dimorphism (difference in size between males and females) increases with body size when males are larger. Conversely, it decreases with body size when females are larger.

Rosa's Rule

Rosa's rule underlines an evolutionary trajectory wherein groups evolve from displaying character variation in ancestral species to a more fixed character state in the advanced or derived species.

Schmalhausen's Law

In understanding ecological tolerance, Schmalhausen's law posits that any population at the limit of its tolerance in one aspect becomes highly vulnerable to even slight variations in any other environmental aspect.

Thorson's Rule

Touching on marine invertebrate reproduction, Thorson's rule states that the number of eggs produced by benthic marine invertebrates tends to decrease with increasing latitude.

Van Valen's Law

In the larger scope of evolutionary time, Van Valen's law suggests that the probability of extinction for a particular taxonomic group remains constant, irrespective of the group's lifespan.

von Baer's Laws

Embryology offers some fascinating insights, and von Baer's laws are a testament to that. These laws state that embryos of different species start from a generalized form and progressively develop into increasingly specialized forms.

Williston's Law

Underlying the principles of evolutionary specialization, Williston's law suggests that, over time, parts in an organism become reduced in number but more specialized in function.

Conclusion:

The diverse set of biological rules underscores the interconnectedness and patterns in nature. While each rule provides a snapshot into a specific facet of biology, collectively, they paint a picture of the intricate mechanisms and evolutionary pressures shaping life on Earth.

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  M. exilis skeletal

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  Bergmann's Rule

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  Dollo's law of irreversibility

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  Bombus bohemicus - Keila

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  Sykora02

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  Cambrian Trilobite Olenoides Mt. Stephen

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  Common Crayfish (Astacus fluviatilis, Male)