The human populations with haplogroup I expanded around 15kya, which coincides with estimates for the TMRCA and divergence of subclades of I. It is at this time that subclade I1 is thought to populate Fennoscandia (present day countries of Norway, Sweden, and Finland). The migration likely took place through present day France, Germany and Denmark, though the exact routes are not known with certainty. Subsequent expansion and migration of an I1 subclade and its subclades populated the British Isles and Iceland. The Vikings were the likely candidates for the spread of I1 subclades and there are studies that link the Celtic, Anglo-Saxon and Germanic heritages to I1. The Balkan refuge, representing subclade I2 likely spread northeast into Russia. The populations comprising I2 are tightly linked with Slavs. The subclade, I2a2, found almost exclusively in Sardinia where it makes up nearly 40% of all haplogroups on this island is also present in France and Iberia and makes these locations the likely source of this unique branch of I.
The further refinement of Y-chromosome ancestry can be obtained by using the Y-chromosome Haplogroup I Subclade Testing Panel from Genebase. This panel is based upon a collection of 22 SNPs that identify 21 different subclades of Y-chromosome haplogroup I. The phylogenetic relationships for the I subclade branches are also provided in the table below.
Subclade
Mutations
Previous nomenclature
I*
M258 (2004)
I*
I1
M258 (2004)
M253 (2004)
I1
I1a
M258 (2004)
M253 (2004)
M21 (2001)
I1a
I1b
M258 (2004)
M253 (2004)
M227 (2004)
I1b
I1b1
M258 (2004)
M253 (2004)
M227 (2004)
M72 (2000)
I1b1
I1c
M258 (2004)
M253 (2004)
P259 (May 2008)
I1d
I1d
M258 (2004)
M253 (2004)
L22 (Dec 2008)
I1d1
M258 (2004)
M253 (2004)
P109 (May 2008)
I1c
I2
M258 (2004)
M438 (May 2008)
I2
I2a
M258 (2004)
M438 (May 2008)
P37.2 (2002)
I2a
I2a1
M258 (2004)
M438 (May 2008)
P37.2 (2002)
M26 (2004)
I2a2
I2a1a
M258 (2004)
M438 (May 2008)
P37.2 (2002)
M26 (2004)
M161 (2000)
I2a2a
I2a2
M258 (2004)
M438 (May 2008)
P37.2 (2002)
M423 (May 2008)
I2a1
I2a2a
M258 (2004)
M438 (May 2008)
P37.2 (2002)
M423 (May 2008)
P41.2 (2002)
I2a1a
I2a2b
M258 (2004)
M438 (May 2008)
P37.2 (2002)
M423 (May 2008)
L69(=T) (Jan 2009)
I2b
M258 (2004)
M438 (May 2008)
M436 (May 2008)
I2b
I2b1
M258 (2004)
M438 (May 2008)
M436 (May 2008)
M223 (2001)
I2b1
I2b1a
M258 (2004)
M438 (May 2008)
M436 (May 2008)
M223 (2001)
M284 (2004)
I2b1a
I2b1b
M258 (2004)
M438 (May 2008)
M436 (May 2008)
M223 (2001)
M379 (2006)
I2b1b
I2b1c
M258 (2004)
M438 (May 2008)
M436 (May 2008)
M223 (2001)
P78 (2005)
I2b1c
I2b1d
M258 (2004)
M438 (May 2008)
M436 (May 2008)
M223 (2001)
P95 (2005)
I2b1d
I2b2
M258 (2004)
M438 (May 2008)
M436 (May 2008)
L38 (Dec 2008)
If you are a confirmed member of Y-DNA Haplogroup I, you can dig further with the Y-DNA I Subclade SNP Test and find out which Subclade of I you descended from.
Y-DNA I Subclade
The human populations with haplogroup I expanded around 15kya, which coincides with estimates for the TMRCA and divergence of subclades of I. It is at this time that subclade I1 is thought to populate Fennoscandia (present day countries of Norway, Sweden, and Finland). The migration likely took place through present day France, Germany and Denmark, though the exact routes are not known with certainty. Subsequent expansion and migration of an I1 subclade and its subclades populated the British Isles and Iceland. The Vikings were the likely candidates for the spread of I1 subclades and there are studies that link the Celtic, Anglo-Saxon and Germanic heritages to I1. The Balkan refuge, representing subclade I2 likely spread northeast into Russia. The populations comprising I2 are tightly linked with Slavs. The subclade, I2a2, found almost exclusively in Sardinia where it makes up nearly 40% of all haplogroups on this island is also present in France and Iberia and makes these locations the likely source of this unique branch of I. 
