Overview

Reconciliation-Assisted Divergence Time Estimation (RADTE / rædˈti:) is a method to date gene trees with the aid of dated species trees. This program can handle a rooted gene tree containing duplication/loss events. The divergence time of duplication nodes are estimated while constraining speciation nodes by transferring the known or pre-estimated divergence time from the species tree to the gene tree.

Dependency

• R: Started developing with 3.5 and most recently tested with 4.1.
• ape
• treeio: required for --generax_nhx

In addition to the above dependencies, RADTE needs an output from a phylogeny reconciliation program. NOTUNG and GeneRax are supported.

• NOTUNG
• GeneRax

Installation

After installing the above dependencies, please download the radte.r script by, for example, git or svn, and change the file permission. You can also download a zipped repository from Code -> Download ZIP above.

# With git
git clone https://github.com/kfuku52/RADTE
cd RADTE

# With svn
svn export https://github.com/kfuku52/RADTE/trunk/radte.r

# Change permission
chmod +x ./radte.r

Options

--species_tree

Species tree with estimated divergence time. Leaves (species) should be labeled as GENUS_SPECIES (e.g., Homo_sapiens). The tree is expected to be ultrametric and branch lengths should represent evolutionary time (e.g., million years). Internal nodes including the root node must be uniquely labeled and the same file should be consistently used for NOTUNG/GeneRax and RADTE. Don't know how to label internal nodes? Try this R one-liner.

R -q -e "library(ape); t=read.tree('species_tree_noLabel.nwk'); \
t[['node.label']]=paste0('s',1:Nnode(t)); \
write.tree(t, 'species_tree.nwk')"

--gene_tree

Rooted newick tree. Leaves (genes) should be labeled as GENUS_SPECIES_GENEID (e.g., Homo_sapiens_ENSG00000102144). The tree is expected to be non-ultrametric and branch lengths should represent substitutions per site. Use the tree that NOTUNG produces because its internal nodes are correctly labeled in accordance with the NOTUNG parsable file, another input for this program.

--notung_parsable

An output file from NOTUNG (tested with version 2.9) can be used to acquire the species–gene relationships in phylogeny reconciliation. See Examples for details.

--generax_nhx

Instead of the NOTUNG output, the NHX tree from GeneRax can also be used as an input. If specified, --gene_tree and --notung_parsable will be ignored. See Examples for details.

--max_age

If duplication nodes are deeper than the root node of the species tree, this value will be used as an upper limit of the root node.

--chronos_lambda

Passed to chronos for divergence time estimation. See chronos in the ape documentation.

--chronos_model

Passed to chronos for divergence time estimation. See chronos in the ape documentation.

--pad_short_edge

Prohibit dated branches shorter than this value. If detected, the branch length is readjusted by transferring a small portion of branch length from the parent branch.

Example 1: RADTE after NOTUNG

For input data, see data/example_notung_01.

# Run NOTUNG in the reconciliation mode
# Don't forget to specify --parsable
java -jar -Xmx2g Notung-2.9.jar \
-s species_tree.nwk \
-g gene_tree.nwk \
--reconcile \
--infertransfers "false" \
--treeoutput newick \
--parsable \
--speciestag prefix \
--maxtrees 1 \
--nolosses \
--outputdir .

# Run RADTE
./radte.r \
--species_tree=species_tree.nwk \
--gene_tree=gene_tree.nwk.reconciled \
--notung_parsable=gene_tree.nwk.reconciled.parsable.txt \
--max_age=1000 \
--chronos_lambda=1 \
--chronos_model=discrete \
--pad_short_edge=0.001

species_tree.nwk

gene_tree.nwk.reconciled

radte_gene_tree_output.nwk

Example 2: RADTE after GeneRax

For input data, see data/example_generax_01. For your own data, please run GeneRax and obtain a nhx file for the gene tree. In Generax, --rec-model UndatedDTL may not be compatible with RADTE, so please use --rec-model UndatedDL.

./radte.r \
--species_tree=species_tree.nwk \
--generax_nhx=gene_tree.nhx \
--max_age=1000 \
--chronos_lambda=1 \
--chronos_model=discrete \
--pad_short_edge=0.001

species_tree.nwk

gene_tree.nhx

radte_gene_tree_output.nwk

Output files

See data/example_notung_01 and data/example_generax_01 for example files.

radte_gene_tree_output.nwk

This is the main output file of RADTE. Branch lengths represent the estimated evolutionary time. Node ages represent the estimated divergence time. The unit of the branch length is the same as that in the input species tree.

radte_*.pdf

RADTE generates pdf files for input and output trees in which nodes are colored (see above examples). Red and blue respectively indicate unconstrained and constrained nodes. While the divergence time of blue nodes is transferred from the species tree, that of red nodes is estimated. When the root node is blue, it means the divergence time is either transferred from the species tree or bounded by --max_age.

radte_calibration_all.tsv

This table contains all identified calibration nodes where the divergence time may be transferred from the species tree to the gene tree.

radte_calibration_used.tsv

This table is a subset of radte_calibration_all.tsv and contain only calibration nodes that are used to transfer the divergence time. A part of calibration points may be dropped if the estimation with all available nodes failed.

radte_gene_tree.tsv

This table summarizes gene tree nodes. In the column event, S and D respectively denote speciation node or duplication node inferred by Notung or GeneRax. The root node is indicated as S(R) or D(R). lower_sp_node and upper_sp_node together indicate which node/branch of the species tree the gene tree node is mapped.

radte_species_tree.tsv

This table summarizes species tree nodes.

radte_calibrated_nodes.txt

This file records what types of gene tree nodes are constrained in the divergence time estimation. RADTE first attempts to constrain all available calibration points transferred from the species tree (R, root node; S, speciation node) for the divergence time estimation by chronos from the ape package. If the estimation succeeded, the content of this file should be RS, because both R and S nodes were used. If the first estimation failed, the constraints are gradually relaxed until successful estimation is obtained. As of version 0.2.0, the order of trials is as follows: RS -> S -> R. This differs from the method described in Fukushima and Pollock (2020), where duplication nodes (D) may be constrained with the upper and lower limits.

Citation

The prototype of RADTE is described in this publication.

Fukushima K, Pollock DD. 2020. Amalgamated cross-species transcriptomes reveal organ-specific propensity in gene expression evolution. Nature Communications 11: 4459 (DOI: 10.1038/s41467-020-18090-8)

Licensing

This program is MIT-licensed. See LICENSE for details.