Taxonomy databases¶
Overview¶
ETE4 contains the ncbi_taxonomy and gtdb_taxonomy modules which
provide utilities to efficiently query a local copy of the NCBI or
GTDB taxonomy databases. The classes NCBITaxa and
GTDBTaxa offer methods to convert from taxid to names (and
vice versa), to fetch pruned topologies connecting a given set of
species, or to download rank, names and lineage track information.
It is also fully integrated with PhyloTree instances through
the annotate_ncbi_taxa() and
annotate_gtdb_taxa() methods.
Differences between NCBI and GTDB taxonomies in ETE4¶
The NCBI taxonomy database is a comprehensive resource for organism names and classifications.It is updated daily and offers multiple access points including a web portal, an FTP server. The database releases its data in a package called “taxdump.tar.gz” which contains several .dmp files.
Taxon in NCBI taxonomyis usually a numeric identifier, commonly representing taxa (“TaxID”), but it can also signify other entities like genetic codes or citations, such as 9606 represents Homo Sapiens.
On the other hand, GTDB taxonomy is distributed as simple text files, uses a genome-based approach for classification, and the identifiers are usually specific to genomes rather than taxa.
Since ETE Toolkit version 3, ETE parses taxdump file and stores it in a local sqlite database to fullfill the methods in ncbi_taxonomy module. We applied the same strategy to GTDBTaxa. While the original GTDB taxonomy data differs from NCBI taxonomy files, a conversion step is essential for integration.
To integrate GTDB into the ETE Toolkit v4, a conversion process is necessary. A third-party script (https://github.com/nick-youngblut/gtdb_to_taxdump) is employed to convert the GTDB taxonomy to the NCBI-like taxdump format. We already preprared GTDB taxonomy dump file from different releases version and store in https://github.com/etetoolkit/ete-data/tree/main/gtdb_taxonomy.
Setting up local copies of the NCBI and GTDB taxonomy databases¶
The first time you attempt to use NCBITaxa or GTDBTaxa, ETE will detect that your local database is empty and will attempt to download the latest taxonomy database (NCBI ~600MB, GTDB ~72MB) and will store a parsed version of it in ~/.local/share/ete/ by default. All future imports of NCBITaxa or GTDBTaxa will detect the local database and will skip this step.
NCBI Example:
# Load NCBI module and update the taxonomy database.
from ete4 import NCBITaxa
ncbi = NCBITaxa()
ncbi.update_taxonomy_database()
GTDB Example:
# Load GTDB module and update the taxonomy database.
from ete4 import GTDBTaxa
gtdb = GTDBTaxa()
answer = input('Which version? [file name or "latest"]: ')
if answer == 'latest': # downloads the latest from the internet
gtdb.update_taxonomy_database() # this is the default
else:
fname = answer # it will be a file name like 'gtdb202dump.tar.gz'
gtdb.update_taxonomy_database(fname)
Getting taxid information¶
NCBI taxonomy¶
You can fetch species names, ranks and linage track information for your taxids using the following methods:
|
Return dict with NCBI taxonomy ranks for each list of taxids. |
|
Return lineage track corresponding to the given taxid. |
|
Return dict with the scientific names corresponding to the taxids. |
|
Return dict with taxids corresponding to the given scientific names. |
|
Return list of scientific names corresponding to taxids. |
The so called get-translator functions will return a dictionary converting between taxids and species names. Either species or linage names/taxids are accepted as input.
Example:
from ete4 import NCBITaxa
ncbi = NCBITaxa()
taxid2name = ncbi.get_taxid_translator([9606, 9443])
print(taxid2name)
# {9443: 'Primates', 9606: 'Homo sapiens'}
name2taxid = ncbi.get_name_translator(['Homo sapiens', 'primates'])
print(name2taxid)
# {'Homo sapiens': [9606], 'primates': [9443]}
# When the same name points to several taxa, all taxids are returned.
name2taxid = ncbi.get_name_translator(['Bacteria'])
print(name2taxid)
# {'Bacteria': [2, 629395]}
Other functions allow to extract further information using taxid numbers as a query.
Example:
from ete4 import NCBITaxa
ncbi = NCBITaxa()
print(ncbi.get_rank([9606, 9443]))
# {9443: 'order', 9606: 'species'}
print(ncbi.get_lineage(9606))
# [1, 131567, 2759, 33154, 33208, 6072, 33213, 33511, 7711, 89593, 7742,
# 7776, 117570, 117571, 8287, 1338369, 32523, 32524, 40674, 32525, 9347,
# 1437010, 314146, 9443, 376913, 314293, 9526, 314295, 9604, 207598, 9605,
# 9606]
Example combining all at once:
from ete4 import NCBITaxa
ncbi = NCBITaxa()
lineage = ncbi.get_lineage(9606)
print(lineage)
# [1, 131567, 2759, 33154, 33208, 6072, 33213, 33511, 7711, 89593, 7742,
# 7776, 117570, 117571, 8287, 1338369, 32523, 32524, 40674, 32525, 9347,
# 1437010, 314146, 9443, 376913, 314293, 9526, 314295, 9604, 207598, 9605,
# 9606]
names = ncbi.get_taxid_translator(lineage)
print([names[taxid] for taxid in lineage])
# ['root', 'cellular organisms', 'Eukaryota', 'Opisthokonta', 'Metazoa',
# 'Eumetazoa', 'Bilateria', 'Deuterostomia', 'Chordata', 'Craniata',
# 'Vertebrata', 'Gnathostomata', 'Teleostomi', 'Euteleostomi',
# 'Sarcopterygii', 'Dipnotetrapodomorpha', 'Tetrapoda', 'Amniota',
# 'Mammalia', 'Theria', 'Eutheria', 'Boreoeutheria', 'Euarchontoglires',
# 'Primates', 'Haplorrhini', 'Simiiformes', 'Catarrhini', 'Hominoidea',
# 'Hominidae', 'Homininae', 'Homo', 'Homo sapiens']
GTDB taxonomy¶
In the NCBI taxonomy database, each species is assigned a unique numeric taxid. For example, the taxid 9606 refers to Homo sapiens. These taxids serve as essential keys for tracking lineages within the database.
However, the GTDB database doesn’t originally offer numeric taxids like NCBI does. In the GTDBTaxa module, we’ve introduced taxids for each species to facilitate lineage tracking. These taxids, while not officially recognized in the GTDB database, serve as convenient keys. They help in connecting the lineage and taxonomic ranks within the local database, making it easier for users to fetch and relate taxonomic information.
Like NCBITaxa, GTDBTaxa contains similar methods:
|
Give a list of GTDB string taxids, return a dictionary with their corresponding ranks. |
|
Given a valid taxname, return its corresponding lineage track as a hierarchically sorted list of parent taxnames. |
Getting descendant taxa¶
Given a taxid or a taxa name from an internal node in the NCBI/GTDB taxonomy tree, their descendants can be retrieved as follows:
NCBI taxonomy example:
from ete4 import NCBITaxa
ncbi = NCBITaxa()
descendants = ncbi.get_descendant_taxa('Homo')
print(ncbi.translate_to_names(descendants))
# ['Homo sapiens neanderthalensis', "Homo sapiens subsp. 'Denisova'",
# 'Homo heidelbergensis', 'Homo sapiens environmental sample', 'Homo sp.']
# You can easily ignore subspecies, so only taxa labeled as "species" will be reported:
descendants = ncbi.get_descendant_taxa('Homo', collapse_subspecies=True)
print(ncbi.translate_to_names(descendants))
# ['Homo sapiens environmental sample', 'Homo sapiens', 'Homo heidelbergensis', 'Homo sp.']
# Or even returned as an annotated tree
tree = ncbi.get_descendant_taxa('Homo', collapse_subspecies=True, return_tree=True)
print(tree.to_str(props=['sci_name','taxid']))
# ╭╴environmental samples,2665952╶╌╴Homo sapiens environmental sample,2665953
# │
# ├╴Homo sapiens,9606
# ╴Homo,9605╶┤
# ├╴Homo heidelbergensis,1425170
# │
# ╰╴unclassified Homo,2813598╶╌╴Homo sp.,2813599
GTDB taxonomy example:
from ete4 import GTDBTaxa
gtdb = GTDBTaxa()
descendants = gtdb.get_descendant_taxa('f__Thorarchaeaceae')
print(descendants)
# ['GB_GCA_003662765.1', 'GB_GCA_003662805.1', ..., 'GB_GCA_013138615.1']
# Ignore subspecies, so only taxa labeled as "species" will be reported.
descendants = gtdb.get_descendant_taxa('f__Thorarchaeaceae', collapse_subspecies=True)
print(descendants)
# ['s__MP8T-1 sp002825535', 's__MP8T-1 sp003345545', ..., 's__TEKIR-12S sp004524435']
# Returned as an annotated tree.
descendants = gtdb.get_descendant_taxa('f__Thorarchaeaceae', collapse_subspecies=True, return_tree=True)
print(descendants.to_str(props=['sci_name','rank']))
# ╭╴s__MP8T-1 sp002825535,species
# │
# ├╴s__MP8T-1 sp003345545,species
# │
# ╭╴g__MP8T-1,genus╶┼╴s__MP8T-1 sp002825465,species
# │ │
# │ ├╴s__MP8T-1 sp004524565,species
# │ │
# │ ╰╴s__MP8T-1 sp004524595,species
# │
# │ ╭╴s__SMTZ1-83 sp011364985,species
# │ │
# ├╴g__SMTZ1-83,genus╶┼╴s__SMTZ1-83 sp011365025,species
# │ │
# │ ╰╴s__SMTZ1-83 sp001563325,species
# │
# ├╴g__TEKIR-14,genus╶╌╴s__TEKIR-14 sp004524445,species
# │
# ├╴g__SHMX01,genus╶╌╴s__SHMX01 sp008080745,species
# │
# │ ╭╴s__OWC5 sp003345595,species
# ├╴g__OWC5,genus╶┤
# ╴f__Tho[...]╶┤ ╰╴s__OWC5 sp003345555,species
# │
# ├╴g__JACAEL01,genus╶╌╴s__JACAEL01 sp013388835,species
# │
# ├╴g__B65-G9,genus╶╌╴s__B65-G9 sp003662765,species
# │
# │ ╭╴s__SMTZ1-45 sp001563335,species
# │ │
# │ ├╴s__SMTZ1-45 sp011364905,species
# │ │
# ├╴g__SMTZ1-45,genus╶┼╴s__SMTZ1-45 sp001940705,species
# │ │
# │ ├╴s__SMTZ1-45 sp004376265,species
# │ │
# │ ╰╴s__SMTZ1-45 sp002825515,species
# │
# ├╴g__WTCK01,genus╶╌╴s__WTCK01 sp013138615,species
# │
# ╰╴g__TEKIR-12S,genus╶╌╴s__TEKIR-12S sp004524435,species
Getting species tree topology¶
Getting the taxonomy tree for a given set of species is one of the
most useful ways to get all information at once. The methods
NCBITaxa.get_topology() or GTDBTaxa.get_topology() allow
to query your local NCBI/GTDB database and extract the smallest tree
that connects all your query taxids. It returns a normal ETE tree in
which all nodes, internal or leaves, are annotated for lineage,
scientific names, ranks, and so on.
NCBI taxonomy example:
from ete4 import NCBITaxa
ncbi = NCBITaxa()
tree = ncbi.get_topology([9606, 9598, 10090, 7707, 8782])
print(tree.to_str(props=['sci_name', 'rank']))
# ╭╴Dendrochirotida,order
# │
# │ ╭╴Homo sapiens,species
# ╴Deuterostomia,clade╶┤ ╭╴Homininae,subfamily╶┤
# │ ╭╴Euarchontoglires,superorder╶┤ ╰╴Pan troglodytes,species
# │ │ │
# ╰╴Amniota,clade╶┤ ╰╴Mus musculus,species
# │
# ╰╴Aves,class
# All intermediate nodes connecting the species can also be kept in the tree.
tree = ncbi.get_topology([2, 33208], intermediate_nodes=True)
print(tree.to_str(props=['sci_name']))
# ╭╴Eukaryota╶╌╴Opisthokonta╶╌╴Metazoa
# ╴cellular organisms╶┤
# ╰╴Bacteria
GTDB taxonomy example:
from ete4 import GTDBTaxa
gtdb = GTDBTaxa()
tree = gtdb.get_topology(['p__Huberarchaeota', 'o__Peptococcales', 'f__Korarchaeaceae'])
print(tree.to_str(props=['sci_name', 'rank']))
# ╭╴p__Huberarchaeota,phylum
# ╭╴d__Archaea,superkingdom╶┤
# ╴root,no rank╶┤ ╰╴f__Korarchaeaceae,family
# │
# ╰╴o__Peptococcales,order
# All intermediate nodes connecting the species can also be kept in the tree.
tree = gtdb.get_topology(['p__Huberarchaeota', 'o__Peptococcales', 'f__Korarchaeaceae'], intermediate_nodes=True, collapse_subspecies=True, annotate=True)
print(tree.to_str(props=['sci_name', 'rank']))
# ╭╴p__Huberarchaeota,phylum
# ╭╴d__Archaea,superkingdom╶┤
# ╴root,no rank╶┤ ╰╴p__Thermoproteota,phylum╶╌╴c__Korarchaeia,class╶╌╴o__Korarchaeales,order╶╌╴f__Korarchaeaceae,family
# │
# ╰╴d__Bacteria,superkingdom╶╌╴p__Firmicutes_B,phylum╶╌╴c__Peptococcia,class╶╌╴o__Peptococcales,order
Automatic tree annotation using NCBI/GTDB taxonomy¶
NCBI/GTDB taxonomy annotation consists of adding additional information to any internal or leaf node in a tree. Only a property containing the taxid associated to each node is required for the nodes in the query tree. The annotation process will add the following features to the nodes:
sci_name
taxid
named_lineage
lineage
rank
Note that, for internal nodes, taxid can be automatically inferred
based on their sibling nodes. The easiest way to annotate a tree is to
use a PhyloTree instance where the species name attribute is
transparently used as the taxid attribute. Note that the
annotate_ncbi_taxa() or
annotate_gtdb_taxa() function will also return the
used name, lineage and rank translators.
Remember that species names in PhyloTree instances are automatically extracted from leaf names. The parsing method can be easily adapted to any formatting
Here are some examples using the NCBI taxonomic annotation.
Using the whole leaf name as taxonomic identifier:
from ete4 import PhyloTree
tree = PhyloTree('((9606, 9598), 10090);')
# pass name as taxid identifier to annotate_ncbi_taxa
tax2names, tax2lineages, tax2rank = tree.annotate_ncbi_taxa(taxid_attr='name')
print(tree.to_str(props=['name', 'sci_name', 'taxid']))
# ╭╴9606,Bacteriovorax stolpii,9606
# ╭╴⊗,Bdellovibrionota,3018035╶┤
# ╴⊗,Bacteria,2╶┤ ╰╴9598,Bdellovibrio bacteriovorus,9598
# │
# ╰╴10090,Ancylobacter aquaticus,10090
Using sp_naming_function to define the species attribute for each node:
from ete4 import PhyloTree
# a) Load the whole leaf name as species attribute of each node.
tree = PhyloTree('((9606, 9598), 10090);', sp_naming_function=lambda name: name)
# Pass `species` as taxid identifier to annotate_ncbi_taxa.
tax2names, tax2lineages, tax2rank = tree.annotate_ncbi_taxa(taxid_attr='species')
# Or annotate using only the name as taxid identifier.
tree = PhyloTree('((9606, 9598), 10090);')
tax2names, tax2lineages, tax2rank = tree.annotate_ncbi_taxa(taxid_attr='name')
print(tree.to_str(props=['name', 'sci_name', 'taxid']))
# ╭╴9606,Homo sapiens,9606
# ╭╴⊗,Homininae,207598╶┤
# ╴⊗,Euarchontoglires,314146╶┤ ╰╴9598,Pan troglodytes,9598
# │
# ╰╴10090,Mus musculus,10090
# b) Only take part of the leaf name as species attribute of each node.
# Split names by '|' and return the first part as the species taxid.
tree = PhyloTree('((9606|protA, 9598|protA), 10090|protB);', sp_naming_function=lambda name: name.split('|')[0])
tax2names, tax2lineages, tax2rank = tree.annotate_ncbi_taxa(taxid_attr='species')
print(tree.to_str(props=['name', 'sci_name', 'taxid']))
# ╭╴9606|protA,Homo sapiens,9606
# ╭╴⊗,Homininae,207598╶┤
# ╴⊗,Euarchontoglires,314146╶┤ ╰╴9598|protA,Pan troglodytes,9598
# │
# ╰╴10090|protB,Mus musculus,10090
Using custom property as taxid identifier:
from ete4 import PhyloTree
tree = PhyloTree('((9606|protA, 9598|protA), 10090|protB);')
# Add custom property with namespace "spcode" to each node.
tree['9606|protA'].add_prop('spcode', 9606)
tree['9598|protA'].add_prop('spcode', 9598)
tree['10090|protB'].add_prop('spcode', 10090)
# passing the custom property name as taxid identifier to annotate_ncbi_taxa
tax2names, tax2lineages, tax2rank = tree.annotate_ncbi_taxa(taxid_attr='spcode')
print(tree.to_str(props=['name', 'sci_name', 'spcode']))
# ╭╴9606|protA,Homo sapiens,9606
# ╭╴(empty),Homininae,207598╶┤
# ╴(empty),Euarchontoglires,314146╶┤ ╰╴9598|protA,Pan troglodytes,9598
# │
# ╰╴10090|protB,Mus musculus,10090
Similar to the above examples but using the GTDB taxonomic annotation:
from ete4 import PhyloTree
from ete4 import GTDBTaxa
# Update gtdb taxonomy database.
gtdb = GTDBTaxa()
gtdb.update_taxonomy_database()
# Load the whole leaf name as species taxid.
newick = '((p__Huberarchaeota,f__Korarchaeaceae)d__Archaea,o__Peptococcales);'
tree = PhyloTree(newick)
tax2name, tax2track, tax2rank = tree.annotate_gtdb_taxa(taxid_attr='name')
print(tree.to_str(props=['sci_name', 'rank']))
# ╭╴p__Huberarchaeota,phylum
# ╭╴d__Archaea,superkingdom╶┤
# ╴root,no rank╶┤ ╰╴f__Korarchaeaceae,family
# │
# ╰╴o__Peptococcales,order
# Load the whole leaf name(representing genome) as species taxid.
newick = '((GB_GCA_020833055.1),(GB_GCA_003344655.1),(RS_GCF_000019605.1,RS_GCF_003948265.1));'
tree = PhyloTree(newick, sp_naming_function=lambda name: name)
tax2name, tax2track, tax2rank = tree.annotate_gtdb_taxa(taxid_attr='species')
print(tree.to_str(props=['name', 'sci_name', 'rank']))
# ╭╴⊗,GB_GCA_020833055.1,subspecies╶╌╴GB_GCA_020833055.1,s__Korarchaeum sp020833055,subspecies
# │
# ╴⊗,g__Korarchaeum,genus╶┼╴⊗,GB_GCA_003344655.1,subspecies╶╌╴GB_GCA_003344655.1,s__Korarchaeum sp003344655,subspecies
# │
# │ ╭╴RS_GCF_000019605.1,s__Korarchaeum cryptofilum,subspecies
# ╰╴⊗,s__Korarchaeum cryptofilum,species╶┤
# ╰╴RS_GCF_003948265.1,s__Korarchaeum cryptofilum,subspecies
# Split names by '|' and return the first part as the species taxid.
newick = '((GB_GCA_020833055.1|protA:1):1,(GB_GCA_003344655.1|protB:1):1,(RS_GCF_000019605.1|protC:1,RS_GCF_003948265.1|protD:1):1):1;'
tree = PhyloTree(newick, sp_naming_function=lambda name: name.split('|')[0])
tax2name, tax2track, tax2rank = tree.annotate_gtdb_taxa(taxid_attr='species')
print(tree.to_str(props=['name', 'sci_name', 'rank']))
# ╭╴⊗,GB_GCA_020833055.1,subspecies╶╌╴GB_GCA_020833055.1|protA,s__Korarchaeum sp020833055,subspecies
# │
# ╴⊗,g__Korarchaeum,genus╶┼╴⊗,GB_GCA_003344655.1,subspecies╶╌╴GB_GCA_003344655.1|protB,s__Korarchaeum sp003344655,subspecies
# │
# │ ╭╴RS_GCF_000019605.1|protC,s__Korarchaeum cryptofilum,subspecies
# ╰╴⊗,s__Korarchaeum cryptofilum,species╶┤
# ╰╴RS_GCF_003948265.1|protD,s__Korarchaeum cryptofilum,subspecies
# Using custom property as taxid identifier:
newick = '((protA:1),(protB:1):1,(protC:1,protD:1):1):1;'
tree = PhyloTree(newick)
annotate_dict = {
'protA': 'GB_GCA_020833055.1',
'protB': 'GB_GCA_003344655.1',
'protC': 'RS_GCF_000019605.1',
'protD': 'RS_GCF_003948265.1',
}
for key, value in annotate_dict.items():
tree[key].add_prop('gtdb_spcode', value)
tax2name, tax2track, tax2rank = tree.annotate_gtdb_taxa(taxid_attr='gtdb_spcode')
print(tree.to_str(props=['name', 'sci_name', 'rank']))
# ╭╴⊗,GB_GCA_020833055.1,subspecies╶╌╴protA,s__Korarchaeum sp020833055,subspecies
# │
# ╴⊗,g__Korarchaeum,genus╶┼╴⊗,GB_GCA_003344655.1,subspecies╶╌╴protB,s__Korarchaeum sp003344655,subspecies
# │
# │ ╭╴protC,s__Korarchaeum cryptofilum,subspecies
# ╰╴⊗,s__Korarchaeum cryptofilum,species╶┤
# ╰╴protD,s__Korarchaeum cryptofilum,subspecies