The stress gradient hypothesis (SGH) is an evolutionary theory in microbial ecology and community ecology that provides a framework to predict when positive or negative interactions should be observed in an habitat.[1][2] The SGH states that facilitation, cooperation or mutualism should be more common in stressful environments, compared with benign environments (i.e nutrient excess) where competition or parasitism should be more common.[3]

The stress gradient hypothesis, in which ecological interactions shift in a positive direction with increasing environmental stress, is controversial among ecologists, in part because of contradictory support, yet a 2021 meta analysis study compared SGH across different organisms with intraspecificity and interspecificity interacrions and conclude that the SGH is indeed a broadly relevant ecological phenomena that is currently held back by cross-disciplinary communication barriers.[4]

SGH is well supported by studies that feature bacteria, plants, terrestrial ecosystems, interspecific negative interactions, adults, survival instead of growth or reproduction, and drought, fire, and nutrient stress.

Drought and nutrient stress, especially when combined, shift ecological interactions positively

References

  1. ↑ Bertness, Mark D.; Callaway, Ragan (May 1994). "Positive interactions in communities". Trends in Ecology & Evolution. 9 (5): 191–193. doi:10.1016/0169-5347(94)90088-4. ISSN 0169-5347. PMID 21236818.
  2. ↑ Holmgren, M.; Scheffer, M. (2010). "Strong facilitation in mild environments: the stress gradient hypothesis revisited". Journal of Ecology. 98 (6): 1269–1275. doi:10.1111/j.1365-2745.2010.01709.x. S2CID 83827444.
  3. ↑ Hammarlund, Sarah P.; Harcombe, William R. (2019-07-18). "Refining the stress gradient hypothesis in a microbial community". Proceedings of the National Academy of Sciences. 116 (32): 15760–15762. Bibcode:2019PNAS..11615760H. doi:10.1073/pnas.1910420116. ISSN 0027-8424. PMC 6690025. PMID 31320585.
  4. ↑ Adams, Amy E.; Besozzi, Elizabeth M.; Shahrokhi, Golya; Patten, Michael A. (2021-11-13). "A case for associational resistance: Apparent support for the stress gradient hypothesis varies with study system". Ecology Letters. 25 (1): 202–217. doi:10.1111/ele.13917. hdl:11250/2833572. ISSN 1461-023X. PMID 34775662. S2CID 244115652.


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