Connects a biological entity to its taxon of origin.

x is in taxon y if an only if y is an organism, and the relationship between x and y is one of: part of (reflexive), developmentally preceded by, derives from, secreted by, expressed.

http://www.ncbi.nlm.nih.gov/pubmed/17921072

http://www.ncbi.nlm.nih.gov/pubmed/20973947

http://purl.obolibrary.org/obo/IAO_0000125

https://github.com/obophenotype/uberon/wiki/Taxon-constraints

Chris Mungall