 Therefore, the concept of " tree-based " phylogenetic networks, which was introduced by Francis and Steel, has attracted much attention of theoretical biologists in the last few years.
<meaning-changed>  Therefore, the concept of " tree-based " phylogenetic networks, which was introduced by Francis and Steel, has attracted much attention of theoretical biologists in the last few years.
 Therefore, the concept of " tree-based " phylogenetic networks, which are defined by a spanning tree called a subdivision tree, have attracted attention of theoretical biologists in the last few years.