Evolutionary Mismatch

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Evolutionary maladaptation or faulty or lack of adaptation is a principally permanent, evolved deviation of a biological characteristic or a population from adaptations to the environment.

Explanation and history

A mismatched trait is a trait in the population of a species that is less beneficial than an adapted trait for its reproductive success ( fitness ). In this context, a characteristic can be both a morphological peculiarity and a behavior . For a trait to be mismatched, it must be hereditary; H. have a genetic basis.

In the early understanding of the Darwinian theory of evolution, the term evolutionary adaptation was often associated with the fact that populations or characteristics of species are always or must be adapted to their environment due to the accumulating mechanism of mutation and selection. Otherwise they would be hindered in their environment and phylogenetically segregated; non-adapted species could not survive. This is a misinterpretation of Darwin's teaching and the synthetic theory of evolution . Darwin himself had already pointed out that feature adjustments are not perfect. The main cause of the organization of every living being is to be seen in heredity . For this reason, although every species is well adapted as an organism for its place in nature, many organismic structures in living beings have no direct relation to their environment.

With the emergence of the synthetic theory of evolution in the middle of the 20th century, a "blind trust" developed to explain phenotype features uncritically as evolutionary adaptations. Beginning in the 1960s, George C. Williams ' book Adaptation and Natural Selection (1966) sparked an ongoing discussion about the extent and applicability of the concept of evolutionary adaptation. Williams advocated that customization was a "special and tedious concept" and should only be used when really necessary. One should speak of a function that has arisen through adaptation with caution. Biologists contrasted a large number of examples with high adaptation with other examples that showed that organisms are sub-optimally adapted. Gradually the realization took hold that all organisms, from bacteria to humans, show features with adaptations and those with mismatches. For a long time, however, the discussion remained strongly case-related. It was not until the 1980s that the question was increasingly asked whether and how mismatches could be inherent in the evolutionary system and mismatches can evolve.

Stephen J. Gould and Richard Lewontin made a critical contribution in 1979, when they pointed out that many characteristics probably have no adaptation. They are often just “ just like that ” appearances, comparable to spandex grooves on the ceilings of Gothic cathedrals. In 1982, Gould and Vrba added that features could originally have had a different function in earlier times and therefore could not have been created for the function they have today. Both contributions sparked an ongoing discussion about evolutionary adaptation.

Ernst Mayr took a critical position on both theses. He could confirm Darwin's restrictive view of perfect adaptation. Mayr emphasized that adaptation always has a posterior character, that is, since it works via inheritance, it can at best take place on the environment of the respective parent generation. There is no teleological potential for the future. According to Mayr and contrary to Williams' thesis, the goal of selection is always a complete individual and less a single gene. Adaptation is therefore always a compromise ( tradeoff ) between the selective advantages of different organs, different sexes, different stages in the life cycle and different environmental influences. According to Mayr, evolutionary change is not a perfect optimization process. Stochastic processes and other constraints prevent perfect adaptation.

According to the theory of multilevel selection first presented by Sober and Wilson in 1998, there are various levels on which natural selection can attack. The common neo-Darwinian theory that only the individual is the object of selection (or primarily the gene in George Williams and Richard Dawkins ) is supported by an overarching theory, in which both below the individual level (organs, cells, genes) and above (group , Population) selection forces - possibly even simultaneously - can act, replaced. According to the multilevel selection, there is no evolutionary adaptation at the individual level by definition.

From today's point of view, evolutionary mismatches exist on the one hand for populations and characteristics limited in time and place due to the imperfection of nature and its permanent change. Natural selection often varies across populations over time. In addition, there are a number of conditions (see Chapter 2) that lead to mismatches in evolution being seen as systemically immanent and evolving. In 2000, maladjustment was first considered in the context of teleonomy , phylogeny , ontogeny, and genetics .

Mismatch can be defined and represented in the model of the fitness landscapes introduced by Sewall Wright as deviations from local peaks of relative fitness. This is a form of graphic representation of the fitness (reproductive success) of different gene combinations, which can represent both a certain phenotypic characteristic (e.g. vertebrate eye, gills, exoskeleton) and the complete phenotype. Valleys in these landscapes mean less reproductive success of the gene combinations, hills represent more favorable gene combinations. In this model, evolutionary maladjustment means a movement controlled by natural selection on a horizontal contour line or downhill. The trait or population remains mismatched to its environment below the local peak.

Causes of mismatches

Ultimate causes of mismatches lie in considerations of the genetic system in relation to changes in its environment. These changes include mutations , genetic drift , inbreeding , natural selection , pleiotropy , linkage imbalances (" linkage disequilibrium "), heterozygous advantages and gene flow . In the recent past there has been an increased focus on coevolution and exaptation . In the context of evolutionary developmental biology (EvoDevo) , development constraints are researched as obstacles to adaptation.

Mutations

Most mutations are neutral, i.e. any non-adaptation before mismatch, since their effects are independent of adaptive significance.

Genetic drift

Genetic drift is a random change in allele frequency within a population's gene pool. A given adaptation can be reduced by an environmental event (e.g. natural disaster), especially in small and isolated populations, since after the event harmful alleles are stochastically scattered and fixed differently than before ( founder effect ).

inbreeding

Inbred phenotypes show lower vitality and resistance to diseases, since the genetic information is the same in both sets of chromosomes and therefore fewer different alleles are present, which therefore cannot react sufficiently to natural selection and adaptation.

Natural selection

The phenotype usually shows too little genotype variation to be able to react as best as possible to constantly changing environmental changes. Different selection pressures lead to different degrees of adjustment or mismatch. Thus, the selection pressure is largely responsible for adjustment and mismatch.

In general, in contrast to the conventional understanding of mutation, selection is a directed process, but individuals are always subject to diverse, unpredictable, random factors, so that an individual organism with a specific genotype in the selection process can only have a greater probability of a certain reproductive success than other members the population, but no certainty. The stochastic character of the selection represents a significant constraint for adaptation; one might mistakenly conclude that adaptation should lead to better solutions.

Pleiotropy

In pleiotropy , individual genes or gene complexes act on different phenotype features of an organism. The best possible adaptation of all features is not possible or very unlikely. There is a partial adaptation of a certain characteristic of the phenotype, whereas other characteristics of the same gene complex may show a slight adaptation. If the adapted trait is important for the fitness of the organism, natural selection “tolerates” the maladjustment of the less or non-adapted traits.

Coupling imbalance

In the event of a linkage imbalance, two alleles of neighboring gene loci appear more or less frequently as a haplotype than the product of their allele frequencies would suggest. The coupling imbalance can be caused by coupling drift or selection. It leads to limiting effects on the phenotype and thus to maladjustment.

Heterozygous advantage

Heterozygous advantage leads to greater reproductive success in individuals who are heterozygous ( heterozygous ) at a certain gene location than in individuals who are homozygous (homozygous) for the allele pair in question. An example of heterozygous benefit is sickle cell anemia , an inherited disease of red blood cells ( erythrocytes ). In heterozygous carriers, only about one percent of all erythrocytes are deformed. In the heterozygous, milder form, it also gives malaria resistance. In regions outside of Africa the sickle cell allele is practically non-existent, as the selection advantage here is not effective due to the lack of malaria ( spread ).

Gene flow

The gene flow between differently adapted populations can lead to mismatches. The extent of this depends on migration rates and the strength of the selection. Mismatch can be magnified by gene flow when metapopulations inhabit heterogeneous patch habitats in which different alleles are required for different local environmental conditions for optimal adaptations. Mismatching can be reduced by gene flow when metapopulations inhabit homogeneous patch habitats, in which they provide the raw material for optimal adaptations and mitigate mismatching effects through inbreeding.

Coevolution

Coevolution means the sustained, reciprocal change of the selective landscape for the considered species, which evolve in a common ecological environment. With such environmental influences, in which the coevolving species is itself an environmental factor in the ecological sense, populations can only rarely reach adaptive peaks and cannot remain there. In models, conditions can be simulated that in principle do not allow the species under consideration to permanently reach local peaks. Coevolution increases evolutionary complexity. Unlike normal adaptation to physical environmental conditions, adaptation to another species can induce reciprocal genetic responses, since the other species itself evolves in such a way that it improves or worsens the evolutionary influences acting on it.

Mismatches can also arise from interacting evolutionary processes between coevolving island populations that influence the biodiversity of island biogeographies .

Exaptations and Byproducts

Exaptation means the adaptation of a characteristic that is alienated from a phylogenetically original purpose. A modern example is the bird's feather , which did not evolve for flying, but originally as an independent thermoregulation that was not homologous to the reptile scales. Byproducts (byproducts) have no adaptive function at all and therefore cannot be adjusted at all, but still require selection in order to be able to arise as a co-option. An example of a byproduct is the navel , a byproduct of the umbilical cord and thus an adapted function for nourishing the embryo. When it comes to the question of whether a feature can be scientifically assessed as an exaptation or as a byproduct, it has been repeatedly pointed out that the same caution is required here as when assigning adaptive functions for features. The discussion about the adaptation or mismatching of a feature requires knowledge of its function.

At the genomic level, exaptation means the adaptation of a functional DNA sequence that has been phylogenetically alienated from an original purpose (often after duplication) or even the adaptation of a previously functionless DNA sequence. Gould and Brosius described the latter form as a genomic mass with potential for exaptation.

Development constraints

By definition, developmental constraints are ontogenetic obstacles that cannot be changed adaptively at will. As an example, the lungs of whale-like species are given, which can no longer evolve into gills, although gills were present in an earlier phylogenetic phase and would possibly offer fitness advantages in the current phase. Even the vertebrate eye of whale-like species can no longer evolve into the octopus lens eye, which is better adapted for the deep sea, with photoreceptors on the retina that reject light . Often the causes mentioned elsewhere (pleiotropy, coupling imbalance, etc.) are cited under the term development constraints.

Categorization of mismatches

Two classes of maladjustments can be distinguished: firstly, characteristics that can be assumed to have been adapted in earlier times and had a fitness-increasing function, but which no longer work or no longer work as well over time. A large subclass of these are anthropogenic (examples: Section 4.1). A second class of mechanisms are those which, on a genetic, developmental or ecological level, basically prevent better adaptation or a higher degree of fitness from being achieved (Section 2, examples: Section 4.2). The latter can be described as “real” mismatches or mismatches in the narrower sense. In addition to these, there are characteristics with non-adaptation which one must assume that they have no fitness function and as such cannot be adapted or maladjusted. Their discovery, however, has to be seen in the context of the increasing criticism of the unqualified validity of evolutionary adaptation and the exploration of its limits and has had an impact on the understanding of maladjustment.

Examples of mismatches

Mismatches as changes to previously existing adjustments

Climate change

In periods of climate change, such as global warming or cooling, species that were previously climatically well adapted are misadapted to the new climate if they fail to migrate. Incorrect adaptation to climate change with human intervention can arise in situations in which climate protection projects support short-term adaptations, but contain hidden effects that lead to long-term vulnerability or inability of species to adapt to climate change. In the discussion about mismatches caused by climate change, evolutionary mismatches are not necessarily dealt with, but also ecological and economic forms.

Antibiotic resistance

Microorganisms can have properties that enable them to weaken or completely neutralize the effect of antibiotic active substances . Antibiotic producers such as streptomycetes are in most cases resistant to the substances they themselves produce. The maladjustment consists in the resistance to one or more microorganisms (antibiotics), which are used as defense mechanisms against harmful other microorganisms, but no longer work because the organism falsely fends off their damage-limiting effect. Increasing misadapted antibiotic resistance is observed in humans and in factory farming .

Mismatches due to the agricultural revolution

The conversion of humans from hunters and gatherers to a rural way of life ( Neolithic Revolution ) brought with it a quantitative increase determined by high calorie density and a simultaneous qualitative decrease in human food supply determined by industrial production. New epidemic maladjustment diseases were the result of the shift to the agricultural way of life. The mismatches made here are now recognized as such.

Metabolic syndrome

A number of cardiovascular diseases are summarized under the term metabolic syndrome . It is clearly associated with obesity ( adiposity ) and this with insulin resistance , the preliminary stage of type II diabetes . The cause is seen as a lack of genetic adaptability to the rapid evolutionary changes in the human way of life since the middle of the 20th century. As an example, the selected and adapted preference for fatty foods in the prehistory and early history of humans is seen as an important fitness feature, which, when there was a shortage of food, had the function of stimulating vital energy reserves in the form of adipose tissue , while the same feature is today in highly developed societies There is an abundance and has tended to become a maladjustment that is damaging to fitness. Lieberman heads a list of non-contagious maladjustment diseases , including hardening of the arteries , high blood pressure , Crohn's disease , high cholesterol , depression , tooth decay , some forms of cancer , and chronic insomnia . They are all due to "that our Stone Age body is poorly or insufficiently adapted to certain modern behaviors". Liebermann speaks of “ dysevolution ” in this context .

An inactive, sedentary lifestyle has detrimental consequences on human health. A correlation between insufficient physical activity and the development of modern chronic diseases, here the degeneration of heart and skeletal muscles and coronary heart disease, has been proven.

Myopia in children

Nearsightedness (myopia) in children is a rapidly increasing disease of civilization . The maladjustment is also associated with a lengthening of the eyeball in postnatal eye development in childhood. The elongated eyeball shortens the focus point for near vision to a point in front of the retina. Too much near vision in childhood is seen as the cause of the phenotypic maladjustment.

Mismatches as unachieved adjustments

Phantom Pain in Man

Phantom pain can arise in individuals who have lost limbs. The brain reacts incorrectly and misinterprets the body part that is no longer there as still there. The cause lies in the neuroplasticity of the brain, the property of synapses , nerve cells or even entire brain areas to adapt their properties depending on the use. In the case of phantom pain, however, the brain's neuroplastic response is a mismatch in that the brain receives pain signals even though there are no neural pathways and signals from the limb. Today the mechanism cannot be explained in a way that increases fitness.

Lack of paternal concern in ducks

Anatinae , a subfamily of ducks, lack paternal care where it is expected and would promote fitness. A delayed genetic response to selection is seen as the reason.

Small clutches in tits

Birds are expected to have clutch size (number of eggs) large enough to maximize offspring reproduction. This is not the case with observed blue tits and great tits . The observation is based on the gene flow between different populations adapted to local habitats.

Suboptimal gender distribution in fig wasps

Fig wasps lay fertilized eggs inside figs. In certain cases, no females emerge from the brood. In some species, males are wingless after hatching and cannot leave the fig to look for other sex partners. Instead, males compete with their brothers for their sisters. After fertilization, the males die. In such a case, it is expected that mothers will change the gender distribution evolutionarily in favor of more female offspring, since only a few males are required for fertilization. When there are too many males, competition between males leads to mating failures, so the production of these males is a mismatched waste of mothers' resources. A mother who allocates more resources to the production of female offspring would thus be more fit than one who produces fewer females. Low selection pressure is seen as the reason for the mismatch.

Lack of disease resistance in plants

Populations of the climbing plant Amphicarpaea bracteata show genetically very different lineages with regard to resistance to the pathogen Synchytrium . A high degree of self-fertilization prevents recombination and results in a high correlation between disease resistance and other ecologically important characteristics, including morphology. Natural selection for these correlated traits leads to misadapted changes in disease resistance. The plant's mating system is seen as a basic constraint for adaptive improvement in resistance.

See also

literature

  • David M. Buss , Martie G. Haselton, Todd K. Shackelford, April L. Bleske, Jerome C. Wakefield: Adaptations, Exaptations, and Spandrels. In: American Psychologist. Vol. 53, no. 5, 1998, pp. 533-548.
  • Bernard J Crespi: The evolution of maladaptation. In: Heredity. 84, 2000, pp. 623-629, doi: 10.1046 / j.1365-2540.2000.00746.x
  • Timothy E. Farkas, Andrew P. Hendry, Patrik Nosil, Andrew P. Beckerman: How maladaptation can structure biodiversity: eco-evolutionary island biogeography. In: Trends in Ecology & Evolution. Vol. 30, Issue 3, March 2015, pp. 154-160.
  • Daniel E. Liebermann: Our body. History, present, future. S. Fischer, 2015, ISBN 978-3-10-002223-3 .
  • Ernst Mayr : How to Carry Out the Adaptationist Program? In: The American Naturalist. Vol. 121, no. 3, Mar., 1983, pp. 324-334.
  • Randolph M. Nesse: Maladaptation and Natural Selection. In: The Quarterly Review of Biology. 80/1, 2005, pp. 62–71 (pdf)
  • JN Thompson, SL Nuismer, R. Gomulkiewicz: Coevolution and maladaptation. In: Integr Comp Biol. 42 (2), Apr 2002, pp. 381-387. doi: 10.1093 / icb / 42.2.381
  • Terence J Wilkin and Linda D Voss. Metabolic syndrome: maladaptation to a modern world. In: JR Soc Med. 97 (11), Nov 2004, pp. 511-520. doi: 10.1258 / jrsm.97.11.511 . PMC 1079643 (free full text)

Individual evidence

  1. ^ Charles Darwin: On the Origin of Species. 1st edition. John Murray, London 1859, pp. 199-201.
  2. ↑ a b c David M. Buss, Martie G. Haselton, Todd K. Shackelford, April L. Bleske, Jerome C. Wakefield: Adaptations, Exaptations, and Spandrels. In: American Psychologist . Vol. 53, no. 5, 1998, pp. 533-548.
  3. ↑ George Williams: Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought. Princeton University Press, Princeton 1966.
  4. ↑ a b Randolph M. Nesse: Maladaptation and Natural Selection . In: The Quarterly Review of Biology . tape 80 , no. 1 , 2005, p. 62-71 ( PDF ).
  5. ^ A b S. J. Gould, RC Lewontin: The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Program . In: Proceedings of the Royal Society B: Biological Sciences . tape 205 , no. 1161 , September 1979, p. 581-598 , doi : 10.1098 / rspb.1979.0086 ( PDF ).
  6. ↑ a b Stephen Jay Gould, Elisabeth S. Vrba: Exaptation - a missing term in the science of form . In: Paleobiology . tape 8 , no. 1 , 1982, pp. 4–15 , doi : 10.1017 / S0094837300004310 ( PDF ).
  7. ↑ a b c d Ernst Mayr: How to Carry Out the Adaptationist Program? In: The American Naturalist . tape 121 , no. 3 , March 1983, doi : 10.2307 / 2461153 ( PDF ).
  8. ^ Elliott Sober, David Sloan Wilson, Unto Others: The Evolution and Psychology of Unselfish Behavior. Harvard University Press, Cambridge 1988.
  9. ^ A b Bernard J. Crespi: The evolution of maladaptation . In: Heredity . tape 84 , no. 6 , June 2000, p. 623-629 , doi : 10.1046 / j.1365-2540.2000.00746.x ( PDF ).
  10. ^ A b John N. Thompson, Scott L. Nuismer, Richard Gomulkiewicz: Coevolution and Maladaptation . In: Integrative and Comparative Biology . tape 42 , no. 2 , April 2002, p. 381-387 , doi : 10.1093 / icb / 42.2.381 ( PDF ).
  11. ^ S. Wright: Proceedings of the Sixth International Congress on Genetics . 1932, The roles of mutation, inbreeding, crossbreeding, and selection in evolution, p. 355-366 (English, blackwellpublishing.com [PDF]).
  12. ↑ Richard Dawkins : Summit of the Improbable: Miracles of Evolution. rororo, 2008, p. 85ff.
  13. ↑ Coupling imbalance (Spektrum.de)
  14. ↑ Heterozygote advantage (Spektrum.de)
  15. ↑ a b c d Timothy E. Farkas, Andrew P. Hendry, Patrik Nosil, Andrew P. Beckerman: How maladaptation can structure biodiversity: eco-evolutionary island biogeography . In: Trends in Ecology & Evolution . tape 30 , no. 3 , March 2015, p. 154 , doi : 10.1016 / j.tree.2015.01.002 .
  16. ↑ Jürgen Brosius, Stephen Jay Gould: On "genomenclature": a comprehensive (and respectful) taxonomy for pseudogenes and other "junk DNA". In: PNAS . Volume 89, No. 22, 1992, pp. 10706-10710, full text (PDF; 1.2 MB)
  17. ↑ a b Alexandre Magnan: Avoiding maladaptation to climate change: towards guiding principles . In: SAPIEN.S . No. 7.1 , March 30, 2014 ( revues.org ).
  18. ↑ Maladaptation. The negative spin-off: exploring the issue of increased risk as a result of adaptation activities.
  19. ^ Daniel E. Liebermann: Our body. History, present, future. S. Fischer, 2015, pp. 261ff, 311f.
  20. ↑ Editorial: Maladaptation. ( Memento from September 28, 2015 in the Internet Archive ) In: Global Environmental Change. 20, 2010, pp. 211-213.
  21. ^ Terence J. Wilkin, Linda D. Voss: Metabolic syndrome: maladaptation to a modern world . In: Journal of the Royal Society of Medicine . tape 97 , no. November 11 , 2004, doi : 10.1258 / jrsm.97.11.511 , PMC 1079643 (free full text).
  22. ^ Daniel E. Liebermann: Our body. History, present, future. S. Fischer, 2015, p. 216ff.
  23. ↑ Harvard professor shares insights on human evolution and dysevolution
  24. ↑ Robert Tyler Morris: maladaptation of cardiac and skeletal muscle in chronic disease: effects of exercise. Dissertation. 2007.
  25. ^ Study Forecasts Future Myopia in Children. One test before first grade predicts myopia by eighth grade.
  26. ↑ Myopia Myopia children.  ( Page no longer available , search in web archives ) ZDF Mediathek, September 25, 2015.@1@ 2Template: Toter Link / www.zdf.de
  27. ↑ Elena Nava, Brigitte Röder: Adaptation and maladaptation: insights from brain plasticity . In: AM Green, CE Chapman, JF Kalaska, F. Lepore (Eds.): Progress in Brain Research . tape 191 , 2011, chap. 12 , p. 177-194 , doi : 10.1016 / B978-0-444-53752-2.00005-9 ( PDF ).
  28. ↑ Kevin P. Johnson, Frank McKinney, Michael D. Sorenson: Phylogenetic constraint on male parental care in the dabbling ducks . In: Proceedings of the Royal Society B: Biological Sciences . tape 266 , no. 1421 , April 1999, p. 759-763 , doi : 10.1098 / rspb.1999.0702 ( PDF ).
  29. ^ André A. Dhondt, Frank Adriaensen, Erik Matthysen, Bart Kempenaers: Nonadaptive clutch sizes in tits . In: Nature . tape 348 , no. 6303 , December 27, 1990, pp. 723-725 , doi : 10.1038 / 348723a0 ( PDF ).
  30. ^ Edward Allen Herre: Optimality, plasticity and selective regime in fig wasp sex ratios . In: Nature . tape 329 , no. 6140 , October 21, 1987, p. 627-629 , doi : 10.1038 / 329627a0 ( PDF ).
  31. ↑ Matthew A. Parker: nonadaptive Evolution of Disease Resistance in at Annual Legume . In: evolution . tape 45 , no. 5 , January 1991, pp. 1209-1217 , doi : 10.2307 / 2409728 .