This is the most pervasive element in the phylogeny module, cataloging the "phylonodes" of tree graphs. Edges are implied by the parent_phylonode_id reflexive closure. For all nodes in a nested set implementation the left and right index will be between the parents left and right indexes.

For example, for orthology, paralogy group identifiers; could also be used for NCBI taxonomy; for sequences, refer to phylonode_feature, feature associated dbxrefs.

This linking table should only be used for nodes in taxonomy trees; it provides a mapping between the node and an organism. One node can have zero or one organisms, one organism can have zero or more nodes (although typically it should only have one in the standard NCBI taxonomy tree).

This is for relationships that are not strictly hierarchical; for example, horizontal gene transfer. Most phylogenetic trees are strictly hierarchical, nevertheless it is here for completeness.

Global anchor for phylogenetic tree.

Tracks citations global to the tree e.g. multiple sequence alignment supporting tree construction.

A phylotree can have any number of slot-value property tags attached to it. This is an alternative to hardcoding a list of columns in the relational schema, and is completely extensible.