One of the tools is
GISAID. In this tool
one can easily produce phylogenetic trees of SARS-CoV-2 genomes. There are
3848 genomes sampled between Dec 2019 and Dec 2020. Many thousands of
variants of SARS-CoV-2 are circulating. To simplify the matter, they are
grouped in clades.
A clade is a genetically well defined lineage that has reached a
frequency of 20% globally and has spread globally (see Tutorials:
Clade Naming & Definitions).
Clade 19A and 19B are sampled in 2019 and 20A, 20B, 20C are sampled
Below is a radial phylogenetic tree with 5 clades:
Radial Phylogenetic Tree of SARS-COV-2
click on image for full size
I like the radial display with 5 clades because the clades are visually
well separated. The direction of time is from the centre outwards to the
circumference. The tree starts at 30th December 2019 with the reference genome (Wuhan, China) and ends at
One can easily switch from one display type to another. The most common
tree type is the Rectangular tree. The reader is encouraged to try out
different display options and data selections (left panel). A map and a
time lapse animation are
The clades are not geographically restricted. To show this, select 'Color by Region':
SARS-COV-2 Rectangular tree with 6 regions indicated.
Time runs from left to right. click on image for full size.
Remarkable: geographic locations are distributed all over the tree. No clade is restricted to one geographic region. This is unnatural for a species. This means different SARS-CO-2 clades have been transported all over the globe. Species have been transported all over the world even before the popularity of air travel, and even before travel by ship, but the genetic fingerprints of SARS-COV-2 offer us unprecedented opportunities to trace the movements of people carrying the virus from continent to continent.
To be continued.