Environmental Errors and Developmental Symbiosis
Environmental Errors and Developmental Symbiosis
In their book, Hernandez and Blazer (2006) discuss genetic and environmental bases for developmental errors in animals. Although much can be speculated and a great deal is known, the use of animals in the research has allowed greater manipulation of various factors. As such, medical science has been more successful in disentangling the nature versus nurture argument that continues to plague human development. While not all of the information learned through animal study can be generalized to humans, it has opened new pathways for research and understanding.
As science has known for some time both genetics and environment play a role in the development of organisms. It has always been unclear however to what degree. Hernandez and Blazer (2006) worked to separate those things that are influenced more greatly by one or the other.
For instance, in their research Hernandez and Blazer (2006) looked at various genetic factors responsible for breast and ovarian cancer. As they manipulated genetic influence in the domesticated rodents, they could manipulate the manifestations of cancer including changing what organs were more likely to be affected and where in the body cancer was likely to appear. However, the same work in wild rats gave different outcomes. According to their work, when wild rats were used the same results did not follow. The genetic errors which caused cancer in domesticated rats yielded different results in wild rat populations. Their results suggested that even those things which are clearly predictable from a genetic aspect in some populations may not be so in other populations where environments are more natural to the species. Hernandez and Blazer suggested that environments more reflective of an animal’s natural habitat might be more effective in studying genetic effects.
The environment alone is certainly capable of causing developmental errors. As an organism develops following its genetic instructions, there may be windows of increased sensitivity to environmental influences. Nutrition, teratogens, and even trauma are all environmental errors which can cause developmental errors (Weiten, 2005). One of the most famous examples was the kitten experiment in which kittens were divided into two groups and one was exposed only to horizontal lines while the other was exposed to only vertical lines. This environment prevented the appropriate development in the visual cortex and once the window for such development had passed the opportunity to learn to see those lines had passed (Weiten).
Developmental symbiosis is when two organisms create a relationship in order for at least one of them to properly develop. There are variations on the types of the relationships. Some of those relationships may be harmful to one while it helps the other. Many seem to have no harmful effects on either but is tantamount to the appropriate development of one, and a relationship of mutualism benefits both organisms involved in the symbiotic relationship.
One common developmental symbiotic relationship occurs in coral reefs (Bucher, Wolfowicz, Voss, Hableton & Guse, 2016). Algae and coral work together to ensure the safety and necessary food supply for the other. Coral polyps close during the sunniest part of the day which allows the algae to access as much light as possible for food production; when the sun is no longer useful, the polyps open, feeding the organism on plankton in the water. This relationship is renewed every generation when the larval organism forms a new relationship and the system of mutualism is renewed (Bucher, Wolfowicz, Voss, Hableton, & Guse).
References
Bucher, M. Wolfowicz, I., Voss, P., Hableton, E., & Guse, A. (2016). Development and symbiosis establishment in the Cnidarian endosymbiosis model Aiptasia sp. Scientific Reports, 6. Doi: 10.1038/srep19867
Hernandez, L. & Blazer, D. (2006). Genes, Behavior, and the Social Environment: Moving Beyond the Nature/Nurture Debate. Washington, DC: National Academies Press.
Weiten, W. (2005). Psychology: Themes and variations (6th ed.). Belmont, CA: Thomson Wadsworth.
