Extinction Cascades
In class, we have discussed general examples of cascading behavior in networks. While most of the examples brought forward have been related to human behavior, new research has shown that a similar processes can take place in biology as well. In this article, published by the University of Exeter, research demonstrates that an initial extinction of a species creates what are called “extinction cascades.” In the article, Dr. Sanders of the University of Exeter describes that “more complex food webs will be less vulnerable to extinction cascades because there is a greater chance that other species can step in and buffer against the effects of species loss.” In the study, researchers aimed to test this statement by using “networks” of plants and insects. Researchers found that the removal of one species of wasp led to extinctions of other species in the network. They found the results to be much more profound in small, simple systems. Dr. Sanders summarized by describing that the results prove how loss of biodiversity can create cascades and increase the chances of further extinctions.
This article directly relates to what we are learning in class because it is an example of cascading behavior in a network. In this example, the “adoption” of an idea, as we have been referring to it in class, is essentially the “adoption” of extinction. Rather than the spread of innovations or ideas, we are looking at the spread of extinction. While this is clearly an example of a cascade, this article also remined me of the relationship between clusters and cascades. As we learned in lecture, clusters are obstacles to cascades. According to the textbook, the spread of a new behavior, when nodes have threshold q, stops when it reaches a cluster of density greater than (1-q). Similarly, as Dr. Sanders described, the chances of an extinction cascade are much greater in smaller ecosystems and food webs. This is because there are many more clusters and species to counteract the effects of an extinction and prevent a large cascade. Finally, I believe the creation of a network coordination game may help further clarify the more specific impacts of extinction on an ecosystem.