The POMEROY GENETICS PROJECT #4
Phylogenetic Network for POMs belonging in Haplogroup 1
31 of the 51 testees fell into Haplogroup 1 (referred to from now on as HG-1). The resulting phylogenetic network
shown in Chart One is very compact. Few potential nodes are without samples and 7 of the 15 nodes have more than a
single sample. The most common haplotype was recorded in seven of the testees; put another way, almost a
quarter of the testees found to belong in HG-1 belong to this single haplotype and so we can guess that they are
highly likely to share a common male lineage ancestor.
CHART ONE
While this mapping of the number of testees is a useful start we can make the tree more meaningful by replacing
the figures in each node (representing the number of tested POMs found per haplotype) with by that of the sum of all the adult
living male UK POMs we know are linked to the tested POMs in each haplotype. To recap, each person that was tested is part of a known
family tree. If it is a small tree they may be the only living adult male known to belong to it, but if it is a
relatively big tree then there might be several living adult male POMS linked
to it. All testees were not therefore equal, and indeed the broadest tree represented by a single testee has
49 living adult males in it, around one in twenty-five of the entire UK population of POMs!
CHART TWO
Chart Two above sums all the living adult male POMs in each haplotype. If you compare charts One and Two you will notice some
small differences. The largest group is still the largest, but second-, third- and fourth-ranking have all changed order.
Some of the single-testee haplotypes now look more significant than others and some of the double-testee ones
much less so. Totalling 215 living adult males, the trees linked by the DNA tests probably cover a quarter of all
UK-based adut male POMs.
The count figure in Chart Two is significant within the test set of POMs. But the figures for each haplotype are only
really important if their frequency of occurance is significantly greater than that of the control population.
Within our own test set a large count *may* be significant and indicate a mutational link and a common male ancestor
shared with a haplotype that is one-step (or one node) away, but if that nearby haplotype is much rarer in the control
population than in our test set we can be much more confident that the link it is as the result of a genetic mutation
rather than because of some non-POM interloper's DNA.
CHART THREE
In Chart Three above the circles in red indicate haplotypes where the count of testees is ten or more times frequent
than in the control group and those in black indicate where it is less than ten times.
The single rosy-coloured circle indicates
that this particular haplotype was not found in the control group at all, and since we had four POM testees with
this same haplotype we can be very confident they all share the same male ancestor.
Chart Three is already indicating the most significant haplotypes (compared to the control population in the UK)
and the ones with the largest number of living adult male UK-based POMs in them. But this is perhaps biased towards
shallow but broad family trees, families that have expanded most recently. Perhaps the picture would different if we
substituted the figures for all POMs, male and female, known in the trees that have been built up from documentary evidence
and that are now linked by the DNA tests to each haplotype instead of restricting ourselves to just the living adult male POMs?
CHART FOUR
The most interesting feature of Chart Four above is that each of the significant haplotypes (the red circles) are
revealed also as the deepest, most-populous trees as a result of current documentary research. To give a sense of
perspective, the circle in the centre marked 66 is my own family which we can trace back only 150 years. Clearly there
is a set of five haplotypes visible each with more than 200 historical POMs in their trees, and then a
second set with fewer than 35 in them. Note also that one major historical tree with 315 POMs
in it is represented by just a single testee.
CHART FIVE
The hunt for us is to try and identify the major groups of POMs that probably have unique male ancestors.
These are groups that are unrelated to each other in any timeframe that a family historian would usefully recognise.
Chart Five above sketches out our current idea of four distinct ancestor groups.
(Again, I'll consider later on why and how that idea might need to be changed.)
Group ONE in the upper left corner is a single-step mutation between two haplotypes that are very rare in the
control population. With 550 known members in the trees of these four testees they represent perhaps one in twenty
of all POMs that have ever lived in the past five hundred years in the UK. It's a major group!
Group FOUR in the lower
right-hand corner is comprised of four testees whose haplotype does not appear in the control population. The fact
that the total number of POMs in their historic trees is lower than Group ONE is not necessarily important as this
could simply be that less documentary research has been done on them to date.
Groups TWO and THREE are also significant vis-a-vis the control population, but not in
the same degree as Groups ONE and FOUR. They are probably distinct ancestor groups, but they could conceivably
represent more than one founding family.
Next: Phylogenetic Network for 20 POMs in Haplogroup 2
Last updated: 3 October 2001 |
