Lack's principle

Last updated
Birds lay only as many eggs as they will be able to provide for. Feeding time, all the time - Flickr - Lip Kee.jpg
Birds lay only as many eggs as they will be able to provide for.
If there are too many mouths to feed, fewer young will survive, reducing the parents' reproductive fitness. Sykora02.jpg
If there are too many mouths to feed, fewer young will survive, reducing the parents' reproductive fitness.

Lack's principle, proposed by the British ornithologist David Lack in 1954, 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". [1] As a biological rule, the principle can be formalised and generalised to apply to reproducing organisms in general, including animals and plants. Work based on Lack's principle by George C. Williams and others has led to an improved mathematical understanding of population biology.

Contents

Principle

Lack's principle implies that birds that happen to lay more eggs than the optimum will most likely have fewer fledglings (young that successfully fly from the nest) because the parent birds will be unable to collect enough food for them all. [1] Evolutionary biologist George C. Williams notes that the argument applies also to organisms other than birds, both animals and plants, giving the example of the production of ovules by seed plants as an equivalent case. Williams formalised the argument to create a mathematical theory of evolutionary decision-making, based on the framework outlined in 1930 by R. A. Fisher, namely that the effort spent on reproduction must be worth the cost, compared to the long-term reproductive fitness of the individual. [2] Williams noted that this would contribute to the discussion on whether (as Lack argued) an organism's reproductive processes are tuned to serve its own reproductive interest (natural selection), or as V.C. Wynne-Edwards proposed, [3] to increase the chances of survival of the species to which the individual belonged (group selection). The zoologist J.L. Cloudsley-Thompson argued that a large bird would be able to produce more young than a small bird. [4] Williams replied that this would be a bad reproductive strategy, as large birds have lower mortality and therefore a higher residual reproductive value over their whole lives (so taking a large short-term risk is unjustified). [5] Williams' reply "is one of the most cited papers in life history evolution because it ... made it conceptually possible to find the optimal life history strategies in age-structured populations". [6]

See also

Related Research Articles

Natural selection Mechanism of evolution by differential survival and reproduction of individuals

Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with artificial selection, which in his view is intentional, whereas natural selection is not.

Reproduction Biological process by which new organisms are generated from one or more parent organisms

Reproduction is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. There are two forms of reproduction: asexual and sexual.

Sexual selection Mode of natural selection involving the choosing of and competition for mates

Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex. These two forms of selection mean that some individuals have greater reproductive success than others within a population, for example because they are more attractive or prefer more attractive partners to produce offspring. Successful males benefit from frequent mating and monopolizing access to one or more fertile females. Females can maximise the return on the energy they invest in reproduction by selecting and mating with the best males.

Sex Trait that determines an individuals sexually reproductive function

Sex is the trait that determines whether a sexually reproducing animal or plant produces male gametes or female ones. Male plants and animals produce smaller gametes while females produce larger ones. Organisms that produce both types of gametes are called hermaphrodites. During sexual reproduction, male and female gametes fuse to form zygotes, which develop into offspring that inherit traits from each parent.

Kin selection Evolutionary strategy favoring relatives

Kin selection is the evolutionary strategy that favours the reproductive success of an organism's relatives, even at a cost to the organism's own survival and reproduction. Kin altruism can look like altruistic behaviour whose evolution is driven by kin selection. Kin selection is an instance of inclusive fitness, which combines the number of offspring produced with the number an individual can ensure the production of by supporting others, such as siblings.

Group selection Proposed mechanism of evolution

Group selection is a proposed mechanism of evolution in which natural selection acts at the level of the group, instead of at the level of the individual or gene.

Sex ratio Ratio of males to females in a population

The sex ratio is the ratio of males to females in a population. The ratio tends to be 1:1 in most sexually reproducing species, which is explained by Fisher's principle. Many species deviate from an even sex ratio, either periodically or permanently. Examples include parthenogenic species, periodically mating organisms such as aphids, some eusocial wasps, bees, ants, and termites.

Survival of the fittest Phrase to describe the mechanism of natural selection

"Survival of the fittest" is a phrase that originated from Darwinian evolutionary theory as a way of describing the mechanism of natural selection. The biological concept of fitness is defined as reproductive success. In Darwinian terms, the phrase is best understood as "Survival of the form that will leave the most copies of itself in successive generations."

Adaptation Process that fits organisms to their environment

In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the population during that process. Thirdly, it is a phenotypic trait or adaptive trait, with a functional role in each individual organism, that is maintained and has evolved through natural selection.

Reproductive success Passing of genes on to the next generation in a way that they too can pass on those genes

Reproductive success is an individual's production of offspring per breeding event or lifetime. This is not limited by the number of offspring produced by one individual, but also the reproductive success of these offspring themselves.

Life history theory is an analytical framework designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles. It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan —have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns" and timing of events that make up an organism's life, such as birth, weaning, maturation, death, etc. These events, notably juvenile development, age of sexual maturity, first reproduction, number of offspring and level of parental investment, senescence and death, depend on the physical and ecological environment of the organism.

Parental care

Parental care is a behavioural and evolutionary strategy adopted by some animals, involving a parental investment being made to the evolutionary fitness of offspring. Patterns of parental care are widespread and highly diverse across the animal kingdom. There is great variation in different animal groups in terms of how parents care for offspring, and the amount of resources invested by parents. For example, there may be considerable variation in the amount of care invested by each sex, where females may invest more in some species, males invest more in others, or investment may be shared equally. Numerous hypotheses have been proposed to describe this variation and patterns in parental care that exist between the sexes, as well as among species.

Fisher's principle is an evolutionary model that explains why the sex ratio of most species that produce offspring through sexual reproduction is approximately 1:1 between males and females. A. W. F. Edwards has remarked that it is "probably the most celebrated argument in evolutionary biology".

In behavioral ecology, adaptive behavior is any behavior that contributes directly or indirectly to an individual's reproductive success, and is thus subject to the forces of natural selection. Examples include favoring kin in altruistic behaviors, sexual selection of the most fit mate, and defending a territory or harem from rivals.

Outline of evolution Hierarchical outline list of articles related to evolution

The following outline is provided as an overview of and topical guide to evolution:

Fecundity selection Mode of natural selection

Fecundity selection, also known as fertility selection, is the fitness advantage resulting from the preference of traits that increase the number of offspring. Charles Darwin formulated the theory of fecundity selection between 1871 and 1874 to explain the widespread evolution of female-biased sexual size dimorphism (SSD), where females were larger than males.

Social selection is a hypothesis proposed by Joan Roughgarden as an alternative to sexual selection. Social selection is argued to be a mode of natural selection based on reproductive transactions and a two-tiered approach to evolution and the development of social behavior. Reproductive transactions refer to a situation where one organism offers assistance to another in exchange for access to reproductive opportunity. The two tiers of the theory are behavioral and population genetic. The genetic aspect states that anisogamy arose to maximize contact rate between gametes. The behavioral aspect is concerned with cooperative game theory and the formation of social groups to maximize the production of offspring.

This glossary of evolutionary biology is a list of definitions of terms and concepts used in the study of evolutionary biology, population biology, speciation, and phylogenetics, as well as sub-disciplines and related fields. For additional terms from related glossaries, see Glossary of genetics, Glossary of ecology, and Glossary of biology.

The terminal investment hypothesis is the idea in life history theory that as an organism's residual reproductive value decreases, its reproductive effort will increase. Thus, as an organism's prospects for survival decreases, it will invest more in reproduction. This hypothesis is generally supported in animals, although results contrary to it do exist.

In life history theory, the cost of reproduction hypothesis is the idea that reproduction is costly in terms of future survival and reproduction. This is mediated by various mechanisms, with the two most prominent being hormonal regulation and differential allocation of internal resources.

References

  1. 1 2 Lack, David (1954). The regulation of animal numbers . Clarendon Press.
  2. ↑ Fisher, R. A. (1930). The genetical theory of natural selection. Oxford University Press.
  3. ↑ Wynne-Edwards, V. C. (1962). Animal dispersion in relation to social behavior. Oliver and Boy.
  4. ↑ Cloudsley-Thompson, J. L. (1955). Cragg, J. B.; Pirie, N. W. (eds.). The numbers of man and animals. Oliver and Boyd. pp. 54–55.
  5. ↑ Williams, George C. (November 1966). "Natural Selection, the Costs of Reproduction, and a Refinement of Lack's Principle". The American Naturalist. 100 (916): 687–690. doi:10.1086/282461. JSTOR   2459305. S2CID   84993886.
  6. ↑ Pasztor, E.; Loeschcke, V. (November 1989). "The Coherence of Cole's Result and Williams' Refinement of Lack's Principle". Oikos. 56 (3): 416–420. doi:10.2307/3565627. JSTOR   3565627.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.