Analysis of Ecological Networks

Through my on-going collaborations with Giovanni Strona (EU-supported researcher in Italy) and Dan McGarvey (Virginia Commonwealth University), I’ve become interested in ecological networks. Giovanni and I have been involved with developing new statistical methods to analyze structure in networks. Dan and I have been analyzing species co-occurrence networks developed from large continental databases of the distribution and abundance of stream and river fishes in the USA. We are examining the roles of species functional traits to network properties and specific roles of certain species in networks. We are also investigating the geographic underpinnings of modularity in the networks. My colleague, Ivan Castro-Arellano, here at Texas State University is also interested in ecological networks and metacommunities. He and I have plans for collaborative research in the near future.

In the broadest context, a network consists of nodes connected with each other through linkages (edges) and sometimes internal structuring in the form of modules (subsets of the overall network consisting of highly connected nodes). A linkage almost always entails that the two linked nodes share a feature, property, or entity in common. For example, in species co-occurrence networks, two linked species (nodes) co-occur at a greater-than-randomly-expected number of survey sites, hence they share locations in common. In bipartite networks such as plant-pollinator, two linked pollinator species may share many of the same plant species, and vice versa. Two nodes always share something. Given this perspective it should be possible to apply network-thinking and build networks to investigate a wide array of ecological pattern and process particularly when the nodes are species or particular places in nature.