Evolutionary tradeoff

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An evolutionary tradeoff is a situation in which evolution cannot advance one part of a biological system without distressing another part of it. In biology, and more specifically in

alleles at different loci during the gametic phase).[3]

Background and theory

The general concept behind evolutionary tradeoffs is that in order to increase fitness (or function) in one trait it must come at the expense of the decrease in fitness/function of another trait.[4] The 'Y-model' states that, within an individual, any two traits are determined by resources from a common pool. Although a useful tool that has provided valuable insight, the 'Y-model' has been oversimplified in much of the literature.[3] Researchers have made different mathematical expansions to the 'Y model' in order to gain insights about evolutionary tradeoffs.

An important point that many authors make when discussing the concept of how tradeoffs affect evolutionary change is the ambiguous use of the word 'constraint'. The term 'constraint' has two meanings: hindering (slowing), but not stopping evolution in particular directions, or that there are certain evolutionary trajectories that are not available to selection. The distinction between the two senses of the word is important because according to the first definition all character states, or forms, are possible, where as according to the later definition some character states are unattainable. When discussing evolutionary tradeoffs it is important to make clear which sense of the word is being used.[3]

Life history examples

Evolutionary tradeoffs can be present in a form called life history tradeoffs, which can be defined as the decrease in fitness (essentially, lifetime reproductive success) caused by one life history trait as a result of the increase in fitness caused by a different life history trait.[5] Life history traits are traits closely linked to fitness, such as traits associated with growth rate, body size, stress response, timing of reproduction, offspring quantity/quality, longevity and dispersal.[6]

A classic example of life history tradeoffs is a negative relationship between the age and the size of maturity. Growth rates are negatively correlated with maximal size so that the fastest growing individuals produce the smallest adults and slowly growing individuals produce large adults.

testes mass are negatively associated with investment in precopulatory weaponry.[9]

Life history tradeoffs can also be thought of in the context of adaptation to a specific environment. The general theory is that increased fitness within a selected environment will cause a loss of fitness in other nonelected environments. Researchers have used experimental evolution to test this theory in Escherichia coli evolved in a 20 °C environment. They were able to see that, although not universal (meaning all individuals showed it), generally there was a decrease in fitness of the evolved E. coli when grown in a 40 °C.[10]

Human/clinical examples

Examples of tradeoffs can also be found in studies involving human subjects. A tradeoff can be seen between growth and immune function in human populations in which energy is a limiting factor. A study conducted on rural Bolivia found that children experiencing an elevated

ovarian steroids act as both bone trophic hormones and mitotic stimulants in breast tissue.[13]

See also

References

  1. ^ Garland, T. (2014). Trade-offs. Current Biology, 24(2), R60-R61.
  2. ^ Garland, T., Downs, C. J., & Ives, A. R. (2022). Trade-offs (and constraints) in organismal biology. Physiological and Biochemical Zoology, 95(1), 82–112.
  3. ^ a b c Roff, D. A., & Fairbairn, D. (2007). The evolution of trade‐offs: where are we? Journal of evolutionary biology, 20(2), 433–447.
  4. ^ Ou, Qiang; Vannier, Jean; Yang, Xianfeng; Chen, Ailin; Mai, Huijuan; Shu, Degan; Han, Jian; Fu, Dongjing; Wang, Rong (April 29, 2020). "Evolutionary trade-off in reproduction of Cambrian arthropods".
  5. ^ Zera, A. J., & Harshman, L. G. (2001). The physiology of life history trade-offs in animals. Annual Review of Ecology and Systematics, 32(1), 95–126.
  6. ^ Lancaster, L. A.-O., Morrison, G., & Fitt, R. N. (2017). Life history trade-offs, the intensity of competition, and coexistence in novel and evolving communities under climate change. Philosophical Transactions of the Royal Society BLID https://doi.org/10.1098/rstb.2016.0046 (Electronic)).
  7. ^ Stearns, S. C. (1989). Trade-offs in life-history evolution. Functional Ecology, 3(3), 259–268.
  8. ^ Partridge, L., & Farquhar, M. (1981). Sexual activity reduces lifespan of male fruit flies. Nature, 294(5841), 580–582.
  9. ^ Fitzpatrick, J. L., Almbro, M., Gonzalez‐Voyer, A., Kolm, N., & Simmons, L. W. (2012). Male contest competition and the coevolution of weaponry and testes in pinnipeds. Evolution: International Journal of Organic Evolution, 66(11), 3595–3604.
  10. ^ Bennett, A. F., & Lenski, R. E. (2007). An experimental test of evolutionary trade-offs during temperature adaptation. Proceedings of the National Academy of Sciences, 104(suppl 1), 8649–8654.
  11. ^ McDade, T. W., Reyes‐García, V., Tanner, S., Huanca, T., & Leonard, W. R. (2008). Maintenance versus growth: investigating the costs of immune activation among children in lowland Bolivia. American Journal of Physical Anthropology, 136(4), 478–484.
  12. ^ Scholl, T. O., Hediger, M. L., Schall, J. I., Khoo, C. S., & Fischer, R. L. (1994). Maternal growth during pregnancy and the competition for nutrients. The American Journal of Clinical Nutrition, 60(2), 183–188. https://doi.org/10.1093/ajcn/60.2.183.
  13. ^ Nyirjesy, I. (2003). Breast cancer and hormone-replacement therapy: the Million Women Study. The Lancet, 362(9392), 1330.
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