3 - MRCA
Version 1

Workflow Type: Galaxy

Dating the most recent common ancestor (MRCA) of SARS-CoV-2

Live Resources

usegalaxy.org usegalaxy.eu usegalaxy.org.au usegalaxy.be

Galaxy workflow Galaxy workflow Galaxy workflow Galaxy workflow

Galaxy history Galaxy history Galaxy history Galaxy history

Jupyter Notebook Jupyter Notebook Jupyter Notebook Jupyter Notebook

What's the point?

To estimate the time of COVID-19 emergence we use simple root-to-tip regression (Korber et al. 2000; more complex and powerful phylodynamics methods could certainly be used, but for this data with very low levels of sequence divergence, simpler and faster methods suffice). From the set of all COVID-19 sequences available as of Feb 16, 2020 we obtain an MRCA date of Oct 24, 2019, which is close to other existing estimates Rambaut 2020.


This analysis consists of two components - a Galaxy workflow and a Jupyter notebook. To use a Jupyter Notebook in a Galaxy workflow see these short instructions.

The workflow is used to extract full length sequences of SARS-CoV-2, tidy up their names in FASTA files, produce a multiple sequences alignment and compute a maximum likelihood tree.

The Jupyter notebook is used to correlate branch lengths with collection dates in order to estimate MRCA timing.


One input is required: a comma-separated file containing accession numbers and collection dates:

Accession,Collection_Date MT019531,2019-12-30 MT019529,2019-12-23 MT007544,2020-01-25 MN975262,2020-01-11 ...

An up-to-date version of this file can be generated directly from the NCBI Virus resource by

  1. searching for SARS-CoV-2 (NCBI taxid: 2697049) sequences
  2. configuring the list of results to display only the Accession and Collection date columns
  3. downloading the Current table view result in CSV format

The collection dates will be taken from the corresponding GenBank record's /collection_date tag.


The Galaxy workflow generates a maximum-likelihood phylogenetic tree. This tree and the initial workflow input of accession numbers and collection times are then used in the Jupyter notebook to calculate an estimate of the time to the most recent common ancestor of all samples.

History and workflow

A Galaxy workspace (history) containing the most current analysis can be imported from here.

The publicly accessible workflow can be downloaded and installed on any Galaxy instance. It contains version information for all tools used in this analysis.


Tools used in this analysis are also available from BioConda:

Name Link

ncbi-acc-download Anaconda-Server Badge

picard Anaconda-Server Badge

mafft Anaconda-Server Badge

fasttree Anaconda-Server Badge


ID Name Description Type
CoV acc date CoV acc date n/a
  • File


ID Name Description
1 Remove beginning Remove beginning1
2 Convert Convert characters1
3 Cut Cut1
4 NCBI Accession Download toolshed.g2.bx.psu.edu/repos/iuc/ncbi_acc_download/ncbi_acc_download/0.2.5+galaxy0
5 NormalizeFasta toolshed.g2.bx.psu.edu/repos/devteam/picard/picard_NormalizeFasta/
6 Text transformation toolshed.g2.bx.psu.edu/repos/bgruening/text_processing/tp_sed_tool/1.1.1
7 Collapse Collection toolshed.g2.bx.psu.edu/repos/nml/collapse_collections/collapse_dataset/4.1
8 MAFFT toolshed.g2.bx.psu.edu/repos/rnateam/mafft/rbc_mafft/7.221.3
9 FASTTREE toolshed.g2.bx.psu.edu/repos/iuc/fasttree/fasttree/2.1.10+galaxy1


ID Name Description Type
_anonymous_output_2 _anonymous_output_2 n/a
  • File

Version History

Version 1 (earliest) Created 25th Mar 2020 at 10:02 by Finn Bacall

Added/updated 8 files

Open master fba696f
help Creators and Submitter

Views: 1600   Downloads: 153

Created: 25th Mar 2020 at 10:02

Last updated: 25th Mar 2020 at 11:23

help Tags
help Attributions


Total size: 802 KB
Powered by
Copyright © 2008 - 2024 The University of Manchester and HITS gGmbH