R/K selection theory

Last updated
A North Atlantic right whale with solitary calf. Whale reproduction follows a K-selection strategy, with few offspring, long gestation, long parental care, and a long period until sexual maturity. Eubalaena glacialis with calf.jpg
A North Atlantic right whale with solitary calf. Whale reproduction follows a K-selection strategy, with few offspring, long gestation, long parental care, and a long period until sexual maturity.

In ecology, r/K selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of individual parental investment of r-strategists, or on a reduced quantity of offspring with a corresponding increased parental investment of K-strategists, varies widely, seemingly to promote success in particular environments. The concepts of quantity or quality offspring are sometimes referred to as "cheap" or "expensive", a comment on the expendable nature of the offspring and parental commitment made. [1] The stability of the environment can predict if many expendable offspring are made or if fewer offspring of higher quality would lead to higher reproductive success. An unstable environment would encourage the parent to make many offspring, because the likelihood of all (or the majority) of them surviving to adulthood is slim. In contrast, more stable environments allow parents to confidently invest in one offspring because they are more likely to survive to adulthood.

Contents

The terminology of r/K-selection was coined by the ecologists Robert MacArthur and E. O. Wilson in 1967 [2] based on their work on island biogeography; [3] although the concept of the evolution of life history strategies has a longer history [4] (see e.g. plant strategies).

The theory was popular in the 1970s and 1980s, when it was used as a heuristic device, but lost importance in the early 1990s, when it was criticized by several empirical studies. [5] [6] A life-history paradigm has replaced the r/K selection paradigm, but continues to incorporate its important themes as a subset of life history theory. [7] Some scientists now prefer to use the terms fast versus slow life history as a replacement for, respectively, r versus K reproductive strategy. [8]

Overview

A litter of rats with their mother. The reproduction of rats follows an r-selection strategy, with many offspring, short gestation, less parental care, and a short time until sexual maturity. The same applies to mice. Rat litter.jpg
A litter of rats with their mother. The reproduction of rats follows an r-selection strategy, with many offspring, short gestation, less parental care, and a short time until sexual maturity. The same applies to mice.

In r/K selection theory, selective pressures are hypothesised to drive evolution in one of two generalized directions: r- or K-selection. [2] These terms, r and K, are drawn from standard ecological algebra as illustrated in the simplified Verhulst model of population dynamics: [9]

where N is the population, r is the maximum growth rate, K is the carrying capacity of the local environment, and dN/dt, the derivative of N with respect to time t, is the rate of change in population with time. Thus, the equation relates the growth rate of the population N to the current population size, incorporating the effect of the two constant parameters r and K. (Note that decrease is negative growth.) The choice of the letter K came from the German Kapazitätsgrenze (capacity limit), while r came from rate.

r-selection

r-selected species are those that emphasize high growth rates, typically exploit less-crowded ecological niches, and produce many offspring, each of which has a relatively low probability of surviving to adulthood (i.e., high r, low K). [10] A typical r species is the dandelion (genus Taraxacum ).

In unstable or unpredictable environments, r-selection predominates due to the ability to reproduce rapidly. There is little advantage in adaptations that permit successful competition with other organisms, because the environment is likely to change again. Among the traits that are thought to characterize r-selection are high fecundity, small body size, early maturity onset, short generation time, and the ability to disperse offspring widely.

Organisms whose life history is subject to r-selection are often referred to as r-strategists or r-selected. Organisms that exhibit r-selected traits can range from bacteria and diatoms, to insects and grasses, to various semelparous cephalopods and small mammals, particularly rodents.

K-selection

A bald eagle, an individual of a typical K-strategist species. K-strategists have longer life expectancies, produce fewer offspring and tend to be altricial, requiring extensive care by parents when young. Bald eagle about to fly in Alaska (2016).jpg
A bald eagle, an individual of a typical K-strategist species. K-strategists have longer life expectancies, produce fewer offspring and tend to be altricial, requiring extensive care by parents when young.

By contrast, K-selected species display traits associated with living at densities close to carrying capacity and typically are strong competitors in such crowded niches, that invest more heavily in fewer offspring, each of which has a relatively high probability of surviving to adulthood (i.e., low r, high K). In scientific literature, r-selected species are occasionally referred to as "opportunistic" whereas K-selected species are described as "equilibrium". [10]

In stable or predictable environments, K-selection predominates as the ability to compete successfully for limited resources is crucial and populations of K-selected organisms typically are very constant in number and close to the maximum that the environment can bear (unlike r-selected populations, where population sizes can change much more rapidly).

Traits that are thought to be characteristic of K-selection include large body size, long life expectancy, and the production of fewer offspring, which often require extensive parental care until they mature. Organisms whose life history is subject to K-selection are often referred to as K-strategists or K-selected. [11] Organisms with K-selected traits include large organisms such as elephants, humans, and whales, but also smaller long-lived organisms such as Arctic terns, [12] parrots and eagles.

Continuous spectrum

Although some organisms are identified as primarily r- or K-strategists, the majority of organisms do not follow this pattern. For instance, trees have traits such as longevity and strong competitiveness that characterise them as K-strategists. In reproduction, however, trees typically produce thousands of offspring and disperse them widely, traits characteristic of r-strategists. [13]

Similarly, reptiles such as sea turtles display both r- and K-traits: although sea turtles are large organisms with long lifespans (provided they reach adulthood), they produce large numbers of unnurtured offspring.

The r/K dichotomy can be re-expressed as a continuous spectrum using the economic concept of discounted future returns, with r-selection corresponding to large discount rates and K-selection corresponding to small discount rates. [14]

Ecological succession

In areas of major ecological disruption or sterilisation (such as after a major volcanic eruption, as at Krakatoa or Mount St. Helens), r- and K-strategists play distinct roles in the ecological succession that regenerates the ecosystem. Because of their higher reproductive rates and ecological opportunism, primary colonisers typically are r-strategists and they are followed by a succession of increasingly competitive flora and fauna. The ability of an environment to increase energetic content, through photosynthetic capture of solar energy, increases with the increase in complex biodiversity as r species proliferate to reach a peak possible with K strategies. [15]

Eventually a new equilibrium is approached (sometimes referred to as a climax community), with r-strategists gradually being replaced by K-strategists which are more competitive and better adapted to the emerging micro-environmental characteristics of the landscape. Traditionally, biodiversity was considered maximized at this stage, with introductions of new species resulting in the replacement and local extinction of endemic species. [16] However, the intermediate disturbance hypothesis posits that intermediate levels of disturbance in a landscape create patches at different levels of succession, promoting coexistence of colonizers and competitors at the regional scale.

Application

While usually applied at the level of species, r/K selection theory is also useful in studying the evolution of ecological and life history differences between subspecies, for instance the African honey bee, A. m. scutellata, and the Italian bee, A. m. ligustica. [17] At the other end of the scale, it has also been used to study the evolutionary ecology of whole groups of organisms, such as bacteriophages. [18] Other researchers have proposed that the evolution of human inflammatory responses is related to r/K selection. [19]

Some researchers, such as Lee Ellis, J. Philippe Rushton, and Aurelio José Figueredo, have attempted to apply r/K selection theory to various human behaviors, including crime, [20] sexual promiscuity, fertility, IQ, and other traits related to life history theory. [21] [22] Rushton's developed "differential K theory" to attempt to explain variations in behavior across human races. [22] [23] Differential K theory has been debunked as being devoid of empirical basis, and has also been described as a key example of scientific racism. [24] [25] [26]

Status

Although r/K selection theory became widely used during the 1970s, [27] [28] [29] [30] it also began to attract more critical attention. [31] [32] [33] [34] In particular, a review in 1977 by the ecologist Stephen C. Stearns drew attention to gaps in the theory, and to ambiguities in the interpretation of empirical data for testing it. [35]

In 1981, a review of the r/K selection literature by Parry demonstrated that there was no agreement among researchers using the theory about the definition of r- and K-selection, which led him to question whether the assumption of a relation between reproductive expenditure and packaging of offspring was justified. [36] A 1982 study by Templeton and Johnson showed that in a population of Drosophila mercatorum under K-selection the population actually produced a higher frequency of traits typically associated with r-selection. [37] Several other studies contradicting the predictions of r/K selection theory were also published between 1977 and 1994. [38] [39] [40] [41]

When Stearns reviewed the status of the theory again in 1992, [42] he noted that from 1977 to 1982 there was an average of 42 references to the theory per year in the BIOSIS literature search service, but from 1984 to 1989 the average dropped to 16 per year and continued to decline. He concluded that r/K theory was a once useful heuristic that no longer serves a purpose in life history theory. [43]

More recently, the panarchy theories of adaptive capacity and resilience promoted by C. S. Holling and Lance Gunderson have revived interest in the theory, and use it as a way of integrating social systems, economics and ecology. [44]

Writing in 2002, Reznick and colleagues reviewed the controversy regarding r/K selection theory and concluded that:

The distinguishing feature of the r- and K-selection paradigm was the focus on density-dependent selection as the important agent of selection on organisms' life histories. This paradigm was challenged as it became clear that other factors, such as age-specific mortality, could provide a more mechanistic causative link between an environment and an optimal life history (Wilbur et al. 1974; [31] Stearns 1976, [45] 1977 [35] ). The r- and K-selection paradigm was replaced by new paradigm that focused on age-specific mortality (Stearns, 1976; [45] Charlesworth, 1980 [46] ). This new life-history paradigm has matured into one that uses age-structured models as a framework to incorporate many of the themes important to the r–K paradigm.

— Reznick, Bryant and Bashey, 2002 [7]

Alternative approaches are now available both for studying life history evolution (e.g. Leslie matrix for an age-structured population) and for density-dependent selection (e.g. variable density lottery model [47] ).

See also

Related Research Articles

<span class="mw-page-title-main">Evolution</span> Change in the heritable characteristics of biological populations

Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. The process of evolution has given rise to biodiversity at every level of biological organisation.

<span class="mw-page-title-main">Ecology</span> Study of organisms and their environment

Ecology is the natural science of the relationships among living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps with the closely related sciences of biogeography, evolutionary biology, genetics, ethology, and natural history.

<span class="mw-page-title-main">Heredity</span> Passing of traits to offspring from the species parents or ancestor

Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic information of their parents. Through heredity, variations between individuals can accumulate and cause species to evolve by natural selection. The study of heredity in biology is genetics.

<span class="mw-page-title-main">Natural selection</span> 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 is intentional, whereas natural selection is not.

Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book On the Origin of Species. He also identified sexual selection as a likely mechanism, but found it problematic.

Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and population structure.

Allopatric speciation – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.

<span class="mw-page-title-main">Richard Lewontin</span> American evolutionary biologist and mathematician (1929–2021)

Richard Charles Lewontin was an American evolutionary biologist, mathematician, geneticist, and social commentator. A leader in developing the mathematical basis of population genetics and evolutionary theory, he applied techniques from molecular biology, such as gel electrophoresis, to questions of genetic variation and evolution.

<span class="mw-page-title-main">Niche construction</span> Process by which an organism shapes its environment

Niche construction is the process by which an organism alters its own local environment. These alterations can be a physical change to the organism’s environment or encompass when an organism actively moves from one habitat to another to experience a different environment. Examples of niche construction include the building of nests and burrows by animals, and the creation of shade, influencing of wind speed, and alternation of nutrient cycling by plants. Although these alterations are often beneficial to the constructor, they are not always.

In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection 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.

Human behavioral ecology (HBE) or human evolutionary ecology applies the principles of evolutionary theory and optimization to the study of human behavioral and cultural diversity. HBE examines the adaptive design of traits, behaviors, and life histories of humans in an ecological context. One aim of modern human behavioral ecology is to determine how ecological and social factors influence and shape behavioral flexibility within and between human populations. Among other things, HBE attempts to explain variation in human behavior as adaptive solutions to the competing life-history demands of growth, development, reproduction, parental care, and mate acquisition. HBE overlaps with evolutionary psychology, human or cultural ecology, and decision theory. It is most prominent in disciplines such as anthropology and psychology where human evolution is considered relevant for a holistic understanding of human behavior.

Life history theory (LHT) 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.

Enquiry into the evolution of ageing, or aging, aims to explain why a detrimental process such as ageing would evolve, and why there is so much variability in the lifespans of organisms. The classical theories of evolution suggest that environmental factors, such as predation, accidents, disease, and/or starvation, ensure that most organisms living in natural settings will not live until old age, and so there will be very little pressure to conserve genetic changes that increase longevity. Natural selection will instead strongly favor genes which ensure early maturation and rapid reproduction, and the selection for genetic traits which promote molecular and cellular self-maintenance will decline with age for most organisms.

<span class="mw-page-title-main">Evolutionary physiology</span> Study of changes in physiological characteristics

Evolutionary physiology is the study of the biological evolution of physiological structures and processes; that is, the manner in which the functional characteristics of individuals in a population of organisms have responded to natural selection across multiple generations during the history of the population. It is a sub-discipline of both physiology and evolutionary biology. Practitioners in the field come from a variety of backgrounds, including physiology, evolutionary biology, ecology, and genetics.

Semelparity and iteroparity are two contrasting reproductive strategies available to living organisms. A species is considered semelparous if it is characterized by a single reproductive episode before death, and iteroparous if it is characterized by multiple reproductive cycles over the course of its lifetime. Iteroparity can be further divided into continuous iteroparity and seasonal iteroparity Some botanists use the parallel terms monocarpy and polycarpy.

Ecoimmunology or Ecological Immunology is the study of the causes and consequences of variation in immunity. The field of ecoimmunology seeks to give an ultimate perspective for proximate mechanisms of immunology. This approach places immunology in evolutionary and ecological contexts across all levels of biological organization.

Interlocus sexual conflict is a type of sexual conflict that occurs through the interaction of a set of antagonistic alleles at two or more different loci, or the location of a gene on a chromosome, in males and females, resulting in the deviation of either or both sexes from the fitness optima for the traits. A co-evolutionary arms race is established between the sexes in which either sex evolves a set of antagonistic adaptations that is detrimental to the fitness of the other sex. The potential for reproductive success in one organism is strengthened while the fitness of the opposite sex is weakened. Interlocus sexual conflict can arise due to aspects of male–female interactions such as mating frequency, fertilization, relative parental effort, female remating behavior, and female reproductive rate.

<span class="mw-page-title-main">Reinforcement (speciation)</span> Process of increasing reproductive isolation

Reinforcement is a process of speciation where natural selection increases the reproductive isolation between two populations of species. This occurs as a result of selection acting against the production of hybrid individuals of low fitness. The idea was originally developed by Alfred Russel Wallace and is sometimes referred to as the Wallace effect. The modern concept of reinforcement originates from Theodosius Dobzhansky. He envisioned a species separated allopatrically, where during secondary contact the two populations mate, producing hybrids with lower fitness. Natural selection results from the hybrid's inability to produce viable offspring; thus members of one species who do not mate with members of the other have greater reproductive success. This favors the evolution of greater prezygotic isolation. Reinforcement is one of the few cases in which selection can favor an increase in prezygotic isolation, influencing the process of speciation directly. This aspect has been particularly appealing among evolutionary biologists.

<span class="mw-page-title-main">Laboratory experiments of speciation</span> Biological experiments

Laboratory experiments of speciation have been conducted for all four modes of speciation: allopatric, peripatric, parapatric, and sympatric; and various other processes involving speciation: hybridization, reinforcement, founder effects, among others. Most of the experiments have been done on flies, in particular Drosophila fruit flies. However, more recent studies have tested yeasts, fungi, and even viruses.

This glossary of genetics and evolutionary biology is a list of definitions of terms and concepts used in the study of genetics and evolutionary biology, as well as sub-disciplines and related fields, with an emphasis on classical genetics, quantitative genetics, population biology, phylogenetics, speciation, and systematics. Overlapping and related terms can be found in Glossary of cellular and molecular biology, Glossary of ecology, and Glossary of biology.

References

  1. ↑ "r and K selection". www.bio.miami.edu. Retrieved 2020-10-27.
  2. 1 2 Pianka, E.R. (1970). "On r and K selection". American Naturalist. 104 (940): 592–597. doi:10.1086/282697. S2CID   83933177.
  3. ↑ MacArthur, R.; Wilson, E.O. (1967). The Theory of Island Biogeography (2001 reprint ed.). Princeton University Press. ISBN   978-0-691-08836-5.
  4. ↑ For example: Margalef, R. (1959). "Mode of evolution of species in relation to their places in ecological succession". XVTH International Congress of Zoology.
  5. ↑ Roff, Derek A. (1993). Evolution Of Life Histories: Theory and Analysis. Springer. ISBN   978-0-412-02391-0.
  6. ↑ Stearns, Stephen C. (1992). The Evolution of Life Histories. Oxford University Press. ISBN   978-0-19-857741-6.
  7. 1 2 Reznick, D; Bryant, MJ; Bashey, F (2002). "r-and K-selection revisited: the role of population regulation in life-history evolution" (PDF). Ecology. 83 (6): 1509–1520. doi:10.1890/0012-9658(2002)083[1509:RAKSRT]2.0.CO;2. Archived from the original (PDF) on 2010-12-30. Retrieved 2013-05-11.
  8. ↑ Jeschke, Jonathan M.; Kokko, Hanna (2009). "The roles of body size and phylogeny in fast and slow life histories". Evolutionary Ecology. 23 (6): 867–878. doi:10.1007/s10682-008-9276-y. S2CID   38289373.
  9. ↑ Verhulst, P.F. (1838). "Notice sur la loi que la population pursuit dans son accroissement". Corresp. Math. Phys. 10: 113–121.
  10. 1 2 For example: Weinbauer, M.G.; Höfle, M.G. (1 October 1998). "Distribution and Life Strategies of Two Bacterial Populations in a Eutrophic Lake". Appl. Environ. Microbiol. 64 (10): 3776–3783. Bibcode:1998ApEnM..64.3776W. doi:10.1128/AEM.64.10.3776-3783.1998. PMC   106546 . PMID   9758799.
  11. ↑ "r and K selection" Archived 2014-09-05 at the Wayback Machine . University of Miami Department of Biology. Retrieved February 4, 2011.
  12. ↑ John H. Duffus; Douglas M. Templeton; Monica Nordberg (2009). Concepts in Toxicology. Royal Society of Chemistry. p. 171. ISBN   978-0-85404-157-2.
  13. ↑ Hrdy, Sarah Blaffer (2000), "Mother Nature: Maternal Instincts and How They Shape the Human Species" (Ballantine Books)
  14. ↑ Reluga, T.; Medlock, J.; Galvani, A. (2009). "The discounted reproductive number for epidemiology". Mathematical Biosciences and Engineering. 6 (2): 377–393. doi:10.3934/mbe.2009.6.377. PMC   3685506 . PMID   19364158.
  15. ↑ Gunderson, Lance H.; Holling, C.S. (2001). Panarchy: Understanding Transformations In Human And Natural Systems. Island Press. ISBN   978-1-55963-857-9.
  16. ↑ McNeely, J. A. (1994). "Lessons of the past: Forests and Biodiversity". Biodiversity and Conservation. 3: 3–20. CiteSeerX   10.1.1.461.5908 . doi:10.1007/BF00115329. S2CID   245731.
  17. ↑ Fewell, Jennifer H.; Susan M. Bertram (2002). "Evidence for genetic variation in worker task performance by African and European honeybees". Behavioral Ecology and Sociobiology. 52 (4): 318–25. doi:10.1007/s00265-002-0501-3. S2CID   22128779.
  18. ↑ Keen, E. C. (2014). "Tradeoffs in bacteriophage life histories". Bacteriophage. 4 (1): e28365. doi:10.4161/bact.28365. PMC   3942329 . PMID   24616839.
  19. ↑ VAN BODEGOM, D.; MAY, L.; MEIJ, H. J.; WESTENDORP, R. G. J. (2007). "Regulation of Human Life Histories: The Role of the Inflammatory Host Response". Annals of the New York Academy of Sciences. 1100 (1): 84–97. Bibcode:2007NYASA1100...84V. doi:10.1196/annals.1395.007. PMID   17460167. S2CID   43589115.
  20. ↑ Ellis, Lee (1987-01-01). "Criminal behavior and r/K selection: An extension of gene-based evolutionary theory". Deviant Behavior. 8 (2): 149–176. doi:10.1080/01639625.1987.9967739. ISSN   0163-9625.
  21. ↑ Figueredo, Aurelio José; Vásquez, Geneva; Brumbach, Barbara Hagenah; Schneider, Stephanie M. R. (2007-03-01). "The K-factor, Covitality, and personality". Human Nature. 18 (1): 47–73. doi:10.1007/bf02820846. ISSN   1045-6767. PMID   26181744. S2CID   10877330.
  22. 1 2 Weizmann, Fredric; Wiener, Neil I.; Wiesenthal, David L.; Ziegler, Michael (1990). "Differential K theory and racial hierarchies". Canadian Psychology. 31 (1): 1–13. doi:10.1037/h0078934.
  23. ↑ Peregrine, P (2003). "Cross-cultural evaluation of predicted associations between race and behavior". Evolution and Human Behavior. 24 (5): 357–364. doi:10.1016/s1090-5138(03)00040-0.
  24. ↑ Winston, Andrew S. (29 May 2020). "Scientific Racism and North American Psychology". Oxford Research Encyclopedias: Psychology. doi:10.1093/acrefore/9780190236557.013.516. ISBN   978-0-19-023655-7.
  25. ↑ Weizmann, Frederic; Wiener, Neil I.; Wiesenthal, David L.; Ziegler, Michael (1989). "Scientific racism in contemporary psychology". International Journal of Dynamic Assessment & Instruction. 1 (1): 81–93.
  26. ↑ "Statement from the Department of Psychology regarding research conducted by Dr. J. Philippe Rushton". Department of Psychology, University of Western Ontario.
  27. ↑ Gadgil, M.; Solbrig, O.T. (1972). "Concept of r-selection and K-selection — evidence from wild flowers and some theoretical consideration" (PDF). Am. Nat. 106 (947): 14–31. doi:10.1086/282748. JSTOR   2459833. S2CID   86412666.
  28. ↑ Long, T.; Long, G. (1974). "Effects of r-selection and K-selection on components of variance for 2 quantitative traits". Genetics. 76 (3): 567–573. doi:10.1093/genetics/76.3.567. PMC   1213086 . PMID   4208860.
  29. ↑ Grahame, J. (1977). "Reproductive effort and r-selection and K-selection in 2 species of Lacuna (Gastropoda-Prosobranchia)". Mar. Biol. 40 (3): 217–224. doi:10.1007/BF00390877. S2CID   82459157.
  30. ↑ Luckinbill, L.S. (1978). "r and K selection in experimental populations of Escherichia coli". Science. 202 (4373): 1201–1203. Bibcode:1978Sci...202.1201L. doi:10.1126/science.202.4373.1201. PMID   17735406. S2CID   43276882.
  31. 1 2 Wilbur, H.M.; Tinkle, D.W.; Collins, J.P. (1974). "Environmental certainty, trophic level, and resource availability in life history evolution". American Naturalist. 108 (964): 805–816. doi:10.1086/282956. JSTOR   2459610. S2CID   84902967.
  32. ↑ Barbault, R. (1987). "Are still r-selection and K-selection operative concepts?". Acta Oecologica-Oecologia Generalis. 8: 63–70.
  33. ↑ Kuno, E. (1991). "Some strange properties of the logistic equation defined with r and K – inherent defects or artifacts". Researches on Population Ecology. 33: 33–39. doi:10.1007/BF02514572. S2CID   9459529.
  34. ↑ Getz, W.M. (1993). "Metaphysiological and evolutionary dynamics of populations exploiting constant and interactive resources – r-K selection revisited". Evolutionary Ecology. 7 (3): 287–305. doi:10.1007/BF01237746. S2CID   21296836.
  35. 1 2 Stearns, S.C. (1977). "Evolution of life-history traits – critique of theory and a review of data" (PDF). Annu. Rev. Ecol. Syst. 8: 145–171. doi:10.1146/annurev.es.08.110177.001045. Archived from the original (PDF) on 2008-12-16.
  36. ↑ Parry, G.D. (March 1981). "The Meanings of r- and K-selection". Oecologia. 48 (2): 260–4. Bibcode:1981Oecol..48..260P. doi:10.1007/BF00347974. PMID   28309810. S2CID   30728470.
  37. ↑ Templeton A.R.; Johnson, J.S. (1982). "Life History Evolution Under Pleiotropy and K-selection in a Natural Population of Drosophila mercatorum". In Barker, J.S.F.; Starmer, William T. (eds.). Ecological genetics and evolution: the cactus-yeast-drosophila model system. Academic Press. pp. 225–239. ISBN   978-0-12-078820-0.
  38. ↑ Snell, Terry W.; King, Charles E. (December 1977). "Lifespan and Fecundity Patterns in Rotifers: The Cost of Reproduction". Evolution. 31 (4): 882–890. doi:10.2307/2407451. JSTOR   2407451. PMID   28563718.
  39. ↑ Taylor, Charles E.; Condra, Cindra (November 1980). "r- and K-Selection in Drosophila pseudoobscura". Evolution. 34 (6): 1183–93. doi:10.2307/2408299. JSTOR   2408299. PMID   28568469.
  40. ↑ Hollocher, H.; Templeton, A.R. (April 1994). "The molecular through ecological genetics of abnormal abdomen in Drosophila mercatorum. VI. The non-neutrality of the Y chromosome rDNA polymorphism". Genetics. 136 (4): 1373–84. doi:10.1093/genetics/136.4.1373. PMC   1205918 . PMID   8013914.
  41. ↑ Templeton, A.R.; Hollocher, H.; Johnston, J.S. (June 1993). "The molecular through ecological genetics of abnormal abdomen in Drosophila mercatorum. V. Female phenotypic expression on natural genetic backgrounds and in natural environments". Genetics. 134 (2): 475–85. doi:10.1093/genetics/134.2.475. PMC   1205491 . PMID   8325484.
  42. ↑ Stearns, S.C. (1992). The Evolution of Life Histories. Oxford University Press. ISBN   978-0-19-857741-6.
  43. ↑ Graves, J. L. (2002). "What a tangled web he weaves Race, reproductive strategies and Rushton's life history theory". Anthropological Theory. 2 (2): 2 131–154. doi:10.1177/1469962002002002627. S2CID   144377864.
  44. ↑ Gunderson, L. H. and Holling C. S. (2001) Panarchy: Understanding Transformations in Human and Natural Systems Island Press. ISBN   9781597269391.
  45. 1 2 Stearns, S.C. (1976). "Life history tactics: a review of the ideas". Quarterly Review of Biology. 51 (1): 3–47. doi:10.1086/409052. PMID   778893. S2CID   37813334.
  46. ↑ Charlesworth, B. (1980). Evolution in age structured populations. Cambridge, UK: Cambridge University Press.
  47. ↑ Bertram, Jason; Masel, Joanna (October 2019). "Density-dependent selection and the limits of relative fitness". Theoretical Population Biology. 129: 81–92. doi: 10.1016/j.tpb.2018.11.006 . PMID   30664884.
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.