Monday, September 18, 2017

Guest post: Our taxonomy is not your taxonomy

Bob mesibov The following is a guest post by Bob Mesibov.

Do you know the party game "Telephone", also known as "Chinese Whispers"? The first player whispers a message in the ear of the next player, who passes the message in the same way to a third player, and so on. When the last player has heard the whispered message, the starting and finishing versions of the message are spoken out loud. The two versions are rarely the same. Information is usually lost, added or modified as the message is passed from player to player, and the changes are often pretty funny.

I recently compared ca 100 000 beetle records as they appear in the Museums Victoria (NMV) database and in DarwinCore downloads from the Atlas of Living Australia (ALA) and the Global Biodiversity Information Facility (GBIF). NMV has its records aggregated by ALA, and ALA passes its records to GBIF. The "Telephone" effect in the NMV to ALA to GBIF comparison was large and not particularly funny.

Many of the data changes occur in beetle names. ALA checks the NMV-supplied names against a look-up table called the National Species List, which in this case derives from the Australian Faunal Directory (AFD). If no match is found, ALA generalises the record to the next higher supplied taxon, which it also checks against the AFD. ALA also replaces supplied names if they are synonyms of an accepted name in the AFD.

GBIF does the same in turn with the names it gets from ALA. I'm not 100% sure what GBIF uses as beetle look-up table or tables, but in many other cases their GBIF Backbone Taxonomy mirrors the Catalogue of Life.

To give you some idea of the magnitude of the changes, of ca 85000 NMV records supplied with a genus+species combination, about one in five finished up in GBIF with a different combination. The "taxonRank" changes are summarised in the overview below, and note that replacement ALA and GBIF taxon names at the same rank are often different:


Of the species that escaped generalisation to a higher taxon, there are 42 names with genus triples: three different genus names for the same taxon in NMV, ALA and GBIF.

Just one example: a paratype of the staphylinid Schaufussia mona Wilson, 1926 is held in NMV. The record is listed under Rytus howittii (King, 1866) in the ALA Darwin Core download, because AFD lists Schaufussia mona as a junior subjective synonym of Tyrus howitti King, 1866, and Tyrus howittii in AFD is in turn listed as a synonym of Rytus howittii (King, 1866). The record appears in GBIF under Tyraphus howitti (King, 1865), with Rytus howittii (King, 1866) listed as a synonym. In AFD, Rytus howittii is in the tribe Tyrini, while Tyraphus howitti is a different species in the tribe Pselaphini.

ALA gives "typeStatus" as "paratype" for this record, but the specimen is not a paratype of Rytus howittii. In the GBIF download, the "typeStatus" field is blank for all records. I understand this may change in future. If it does, I hope the specimen doesn't become a paratype of Tyraphus howitti through copying from ALA.

There are lots of "Telephone" changes in non-taxonomic fields as well, including some geographical howlers. ALA says that a Kakadu National Park record is from Zambia and another Northern Territory record is from Mozambique, because ALA trusts the incorrect longitude provided by NMV more than it does the NMV-supplied locality text. GBIF blanks this locality text field, leaving the GBIF user with two African records for Australian specimens and no internal contradictions.

ALA trusts latitude/longitude to the extent of changing the "stateProvince" field for localities near Australian State borders, if a low-precision latitude/longitude places the occurrence a short distance away in an adjoining State.

Manglings are particularly numerous in the "recordedBy" field, where name strings are reformatted, not always successfully. Complex NMV strings suffer worst, e.g. "C Oke; Charles John Gabriel" in NMV becomes "Oke, C.|null" in ALA, and "Ms Deb Malseed - Winda-Mara Aboriginal Corporation WMAC; Ms Simone Sailor - Winda-Mara Aboriginal Corporation WMAC" is reformatted as in ALA "null|null|null|null"

Most of the "Telephone" effect in the NMV-ALA-GBIF comparison appears in the NMV-ALA stage. I contacted ALA by email and posted some of the issues on the ALA GitHub site; I haven't had a response and the issues are still open. I also contacted Tim Robertson at GBIF, who tells me that GBIF is working on the ALA-GBIF stage.

Can you get data as originally supplied by NMV to ALA, through ALA? Well, that's easy enough record-by-record on the ALA website, but not so easy (or not possible) for a multi-record download. Same with GBIF, but in this case the "original" data are the ALA versions.