Using Network Theory to Understand and Predict Biological Invasions
https://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347(19)30134-X#%20
The application of network and graph theory to ecological systems has many implications from the study of evolution within a specific region to the analysis of anthropogenic events over certain periods of time. With the study of network structure and characteristics, trends in evolutionary biology and ecology can be furthered solidified as well as produce fresh perspectives into established fields, such as biological invasions. This paper focuses on the prediction of biological invasions using networks to illustrate their understanding and provide insight into the patterns of ecological network structures that have been derived from the influence of an invasive species, anthropogenic effects, or community resistance. This can be introduced to networks as a changing structure, from the presence of a subset of nodes to the elimination of edges representing interactions between certain species. This paper specifically addresses the representation of biological invasions through graph and networks by defining nodes as sets of organisms (species, individuals, higher taxa, or guilds) and links/edges are their ecological interaction. The most intriguing part of the study was the discussion on the role of network nestedness, the event in which nodes tend to interact with subsets of another node that have better-connected links. I also found the discussion of using bipartite networks to model host-parasite relationships as well as observing patterns to determine the behavior and influence one relationship may have on the entire network structure, such as the relationship between plants-pollinators.
The study of networks in predicting biological invasions is most relevant to the course’s discussion on graph theory and network structures, more specifically the conversation surrounding connectivity in social networks, positive and negative relationships, and network hubs and centrality. This paper most aligns with chapters 2 and 4 of the course textbook as well as the discussion around stable and balanced networks. For instance, the study of ecological networks may aid in predicting which keystone species in a certain network system is integral to that network’s stability and whether its edges or links are positive/negative depending on its interactions with other species. This in turn can show how an invader will influence the entirety of the network thus allow researchers to study and provide further empirical evidence to support the network prediction. This closely aligns to the network datasets or particularly networks in the natural world section within chapter 2 because it is a concrete implication of the study of graphs and networks within evolution and ecology. Through this chapter we discussed how a food web may be represented by a graph and may help reason on issues such as cascading extinctions and chain reactions. The paper is interesting in its discussion on how certain events can be triggered by invasive species and how network-level characteristics interact with other factors such as a species’ phylogenetic and functional trait to influence the outcome of invasions. Much of the paper discussions in depth how the study of networks furthers the study of ecological trends and how future directions within graph and network theory can be applied to analyze and predict accurate occurrences as well as defining concrete network metrics.
https://www.cell.com/action/showPdf?pii=S0169-5347%2819%2930134-X