PageRank and Saving the Environment
https://www.wired.com/2009/09/googlefoodwebs/
This article describes an interesting application of the PageRank algorithm we have been using. The author describes how scientists began looking at a food web in an ecosystem as a strongly connected component of a network, and applying the algorithm to figure out the most crucial parts of the structure. While we discussed that food webs are a good example of networks in nature, it is pretty shocking that the Google-made PageRank algorithm for search optimization can be used to predict ecological collapse.
The application of the model is very similar to what we have seen in class.
“Species are important if they support important species.” This idea makes perfect sense in relation to the PageRank algorithm, which says that hubs are good lists if they point to well endorsed authorities. This circular definition can determine the most important pieces of a network, and therefore the ones that would be most destructive if they disappear. We have seen in class that while it might seem strange to use a recursive idea like this, it does a really good job of narrowing down the most important aspects of a network. Scientists used to believe that the way to determine the most important species in a network was the species that had the most others relying on them for food. However, the PageRank idea shows that importance is all relative. The importance of each species, which can be compared to the authoritativeness of certain pages, is found by the amount of other nodes (hubs) in the network that points to it. Therefore, the most important species are the ones that eat a lot of different species, but also have a lot of species eating them. It also depends on the relative importance of the other species involved in the interaction.
This application of the PageRank algorithm can actually help scientists preserve the environment. They can figure out which species hold the most importance in the structure of a web in a certain area, and work to save them from endangerment/extinction. They can use this to determine the most crucial parts of each ecosystem. It is always interesting to see our networks-based thinking apply in nature as well. Even though the Google PageRank algorithm is man-made, it can help conserve nature!