Figure 2. Winter warming changes topological characteristics and key genes of functional molecule ecological networks (fMENs):(a) the fMEN of control samples; (b) the fMEN of warmed samples. Each dot or diamond represents a node (fungal functional gene), and each line represents an edge (potential interaction). Networks are separated into modules by using the greedy modularity optimization method and shown as separate circles. Diamond nodes represent key genes of fMENs. Diamond nodes inside modules represent module hubs. Diamond nodes outside modules represent connectors. Different colors of diamond nodes represent different functional genes, and the number marked on each diamond node represents fungal species containing the functional gene. Red lines represent negative links, and black lines represent positive links.