Literature on the effect of environmental stress caused by changes in the climate is more relevant today than it has been before, especially in the context of global warming (Beniston 2010). Schulte (2014) and Somero (2010) published articles on environmental stress and climate change respectively. Reading the two articles offers an understanding of how the two variables are interrelated and the effect that they have on living organisms. The manner in which the arguments are constructed presents with various positives and negatives. This critique will highlight the positives and negatives with the help of literature from other scholars.
Schulte (2014) offers an understanding of the various definitions of environmental stressors. In understanding of the interplay between environmental stressors and climate change as well as their effect on living organisms, the review of the various definitions is a positive move. This is because it delineates the extent of what can be described as an environmental stressor. One of the definitions of environmental stressors reviewed by Schulte (2014) is the threat they pose to homeostasis.
This is the definition adopted by Konturek, Brzozowski and Konturek (2011) in exploring the effect of stress of the pathophysiology of the gastrointestinal system. The same definition is also adopted by Kyrou and Tsiqos (2007), Ferguson (2008) and Fink (2009). The positive in this approach is that it introduces the significance of the internal environment in the understanding of stressors. Tomljenovic (2014) argues that the internal cell environment has implications on the homeostasis of living organisms. Variabilities in the internal cell environment amount to stressors and their effect will depend on the ability of the cell to adapt to the variabilities by restoring homeostasis (Oken, Chamine and Wakeland 2015).
The aim of Schulte (2014) was to provide a unified approach through which environmental stressors can be understood. After the evaluation of the various perspectives on the definition of environmental stressors. The use the evolutionary framework to understanding environmental stressors and the response of the animals. This is one of the positives in the article by Schulte (2014) and the subject area. The evolutionary framework has been used effectively by Wenger and Michel (2013) to study how pest insects adapt themselves to changes in the environment when stressors are introduced.
Through the framework, one can understand that the effect of environmental stressors is not felt immediately there is environmental variability. Rana (2013) argues that there is a range of optimal conditions where an organism will function normally. Carter (2017) refers to this as the tolerance range. It consists of a minimum and maximum value. As these values tend towards the periphery of the limits organisms will acclimatize themselves to the changing environment, especially of the changes endure (Seebacher and Franklin 2012 and Sorte 2013).
This finding is another positive, and one that is highlighted by Somero (2010) in the other article. Climate change results in variations in some of the abiotic factors that influence the conditions in which the organisms live. For instance, an increase in the atmospheric temperatures will forces organisms to live within their thermal limits (Brierley and Kingsford 2009; Clarke 2014).
The positive in the arguments by Somero (2010) is that they recognize that different organisms have different tolerance ranges below or above which the stress responses of the organisms will be insufficient. Stressor factors become more significant within the environment of the organism, the organism will employ its acclimatization capacities to adjust itself to the changes in the environment. The persistence of the environmental variabilities enable adaptation at the genetic level where the similar organism living in areas with different environmental conditions will show both phenotypic and genotypic variabilities in their performance as a proxy for their fitness, life span, and response to stress (Somero 2010).
These arguments are illustrated by Schulte (2014) using empirical evidence from the killifish. There are intraspecific variabilities in the tolerance levels and the sensitivity to stressors among the killifish. In some species of killifish can survive the very low temperatures during the winter months as well as the low salinity of the water. This subspecies is dominant in the northern end of the range of the species. The subspecies of killifish on the lower and of the species’ range are found in environments where the temperatures are high and the salinity of the water is high (Schulte 2014).
The findings reported by Schulte (2014) illustrate the influence of the tolerance range as well as the acclimation and adaptation of the organisms to the stressors in their environment within their tolerance range.
Even though Schulte (2014) recommended the use of the evolutionary framework in understanding the environmental stressors, one negative is that his article was not able to recommend one universal definition of stress. Another negative is that the efforts did not yield conclusive information on how stressors interact. The efforts were also impeded by the paucity if information on whether constant environments could be described as sources of stress (Schulte 2014).
One other negative is that while Schulte (2014) alluded to constant environments in trying to discern whether they were stressors, he did not offer an operational definition of the word constant. Even if the environments are what are maintained in a laboratory, which is a controlled environment, the reader can get skeptical about the ability of an individual to keep all the abiotic factors in that environment unchanged. It would benefit the reader an operational definition of the word constant was included as well as the measures used to achieve the constant environment.
This is significant especially when findings by Akbarzadeh et al. (2014) that the significant inter-individual variation in killifish that were held in laboratory conditions reported by Schulte (2014) were not as significant. The antagonistic findings for the same species underscore the sentiments that more research is required in the field. Nonetheless, the arguments that the evolutionary framework is crucial for understanding environmental stress and the response of organisms is apparent and supported (Schulte 2014). More research is required to complete the gaps in knowledge.
References
Akbarzadeh, A., Noori, A., Parto, P., Asadi, M., Yousefzadi, M., Dehghani, H., and Makrani, E. 2014. Responses of the killifish (Aphanius dispar) to long-term exposure to elevated temperatures: growth, survival and microstructure of gill and heart tissues. Mar Freshw Behav Physiol. 47(6): 429-434.
Beniston, M. 2010. Climate change and its impacts: growing stress factors for human societies. Int'l Rev Red Cross. doi:10.1017/S1816383110000342
Brierley, A. and Kingsford, M. 2009. Impacts of climate change on marine organisms and ecosystems. Curr. Biol. 19(14): 602-614.
Carter, K. 2017. What is the ability of an organism to withstand changes in abiotic & biotic factors in an ecosystem? Available from http://sciencing.com/ability-organism- withstand-changes-abiotic-biotic-factors-ecosystem-12648.html [accessed 22 January 2017].
Clarke, A. 2014. The thermal limits to life on earth. Int. J. Astrobiol. 13 (2): 141–154.
Ferguson, D. 2008. Remodeling neuroendocrine receptors to enhance cognitive function and decrease stress-induced anxiety and memory impairments with herpes simplex viral vectors. ProQuest.
Fink, G. 2009. Stress science: neuroendocrinology. Burlington: Elsevier Science.
Konturek, P., Brzozowski, T. and Konturek, S. 2011. Stress and the gut: pathophysiology, clinical consequences, diagnostic approach and treatment options. J. Physiol. Phar. 62(6): 591-599.
Kyrou, I. and Tsiqos, C. 2007. Stress mechanisms and metabolic complications. Horm Metab Res. 39(6): 430-438.
Oken, B., Chamine, I., and Wakeland, W. 2015. A systems approach to stress, stressors and resilience in humans. Behav. Brain Res. 282: 144-154.
Rana, S. V. S. 2013. Essentials of ecology and environmental science. New Delhi. Prentice- Hall Of India Pv.
Schulte, P. 2014. What is environmental stress? Insights from fish living in a variable environment. J. Exp. Biol. 217: 23-24.
Seebacher, F. and Franklin, C. 2012. Determining environmental causes of biological effects: the need for a mechanistic physiological dimension in conservation biology. Phil. Trans. R. Soc. B. 367(1596): 1607-1614.
Somero, G. 2010. The physiology of climate change: how potentials for acclimatization and genetic adaptation will determine ‘winners’ and ‘losers’. J. Exp. Biol. 213: 912-920.
Sorte, C. 2013. Predicting persistence in a changing climate: flow direction and limitations to redistribution. Oikos. 122: 161-170.
Tomljenovic, A. 2014. Effects of internal and external environment on health and well- being: from cell to society. Coll Antropol. 1: 367-372.
Wenger, J. and Michel, A. 2013. Implementing an evolutionary framework for understanding genetic relationships of phenotypically defined insect biotypes in the invasive soybean aphid (Aphis glycines). Evol Appl. 6(7): 1041-1053.
