Comparing Western and Eastern Polynesians

In my last blog entry “Tiny Segments from the Same Common Ancestors“, I began comparing Western Polynesians (Samoans & Tongans), and Eastern Polynesians (Maori and Hawaiians), and compared them to each other in order to show how the tiny segments appeared like missing teeth on the chromosome browser.  Now I will show how people compare to each other based on total centimorgans and their longest block (FTDNA).

First I compare Tongans and Samoans to each other.  Both Samoans and Tongans are Western Polynesians and are the most diverse.   Polynesian settlement began in the west in the Tonga/Samoa/Fiji area.  I mentioned this in a previous entry “Loss of heterozygosity – from Western Polynesia to Eastern Polynesia.”

T = Tongan
S = Samoan
– = no match

I colored it to make it easier to see or compare Tongans to Tongans in light green, and Samoans to Samoans in light blue.  The ones not colored are comparing Samoans to Tongans.  The top number is the total shared in centimorgans, while the bottom number is the longest block (largest segment).  The average totals seem to be between the upper 200s to mid-300s. The lower numbers (in the hundreds) is due to the fact that the person is admixed.  In other words, they are not pure Samoan/Tongan, and usually have some European ancestry.

WestPoly

Comparing Tongans to themselves:
TOTAL
lowest –  117cM (part Tongan)
highest – 340cM
average – 258cM

LONGEST BLOCK
lowest – 5.79cM
highest – 10.51cM
average – 8.54cM

Comparing Samoans to themselves:
TOTAL
lowest – 165cM (part Samoan)
highest – 366cM
average – 271cM

LONGEST BLOCK
lowest – 5.66cM
highest – 16.54cM
average – 9.20cM

Comparing Tongans to Samoans:
TOTAL
lowest –  143cM
highest – 321cM
average – 248cM

LONGEST BLOCK
lowest – 5.79cM
highest – 11.07cM
average – 7.81cM

This is what it looks like when I compare those same Tongans and Samoans to Hawaiians and Maoris who are Eastern Polynesians.

H = Hawaiian
M = Maori
T = Tongan
S = Samoan
? = unable to determine if a match
– = no match

In this graph, I again colored it for easy comparison.  Hawaiian vs. Tongans in light brown, Hawaiians vs. Samoans in golden yellow, Maoris vs. Tongans in pink, and Maoris vs. Samoans in light green.

West-EastPoly

Most of the Eastern Polynesians are admixed except for two Hawaiians and one Maori.  But those that are admixed are still more than 75% Polynesian which still keeps the totals fairly high as you can clearly see it still above one hundred with the exception of one Hawaiian who is admixed to the Tongan that is admixed.  In fact, that admixed Tongan only shares with one Hawaiian and one Maori, both less than 100cM.  Yet their longest block still falls within the range.

Comparing Hawaiians to Tongans:
TOTAL
lowest – 72cM
highest – 341cM
average – 199cM

LONGEST BLOCK
lowest – 5.34cM
highest – 12.12cM
average – 7.94cM

Comparing Hawaiians to Samoans:
TOTAL
lowest –  135cM
highest – 314cM
average – 213cM

LONGEST BLOCK
lowest – 5.09cM
highest – 11.50cM
average -7.57cM

Comparing Maoris to Tongans:
TOTAL
lowest –  68cM
highest – 240cM
average – 202cM

LONGEST BLOCK
lowest – 5.31cM
highest – 10.94cM
average – 7.87cM
Comparing Maoris to Samoans:

TOTAL
lowest –  147cM
highest – 278cM
average – 229cM

LONGEST BLOCK
lowest – 5.28cM
highest – 10.94cM
average -7.81cM

When looking at the average, it seems to be consistent as far as comparing Eastern Polynesians to any Western Polynesian.  However that changes drastically when comparing Eastern Polynesians to themselves.

H = Hawaiian
M = Maori
? = unable to determine if a match
– = no match

I colored Hawaiians in light blue and Maoris in light green when comparing to themselves.  The non-colored portion is when they one group is compared to the other.

EastPoly

Comparing Hawaiians to Hawaiians:
TOTAL
lowest –  225cM
highest – 780cM
average – 463cM

LONGEST BLOCK
lowest – 8.45cM
highest – 23.58cM
average -14.90cM

Comparing Maoris to Maoris:
TOTAL
lowest –  581cM
highest – 694cM
average – 641cM

LONGEST BLOCK
lowest – 12.51cM
highest – 19.98cM
average -16.66cM

Comparing Maoris to Hawaiians:
TOTAL
lowest –  291cM
highest – 773cM
average – 514cM

LONGEST BLOCK
lowest – 8.98cM
highest – 29.68cM
average -16.20cM

So to recap, showing just the average total shared and the average longest block size:Screen Shot 2015-04-20 at 4.45.54 PM

Although I used only 3 Maoris compared to 8 Hawaiians, it was based on the top matches to my mother.  There were a few more Maoris but I did not have access to their data and that would have allowed more “?” in the charts.  But as we can see, the Western Polynesians tend to have lower totals since they are more diverse unlike the Eastern Polynesians.  More admixed Polynesians will result in lower totals, but the longest block is not that much difference from those not admixed.

In the future I will probably attempt to look at admixed Polynesians and compare them to show the average longest block sizes compared to those not admixed.

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Tiny segments from the same common ancestors

Disclaimer: This post demonstrates the use of 1+cM when comparing specific groups of people in order to see patterns of multiple descent from a few ancestors.  It should not be used to validate connections with matches, particularly in this example where connections are beyond a genealogical time frame reaching at least up to 500 years.

Recently I have been comparing both western Polynesian (Tongan and Samoan) and eastern Polynesian (Hawaiian and Maori) matches.  I compared western Polynesians among themselves, and  did the same thing with eastern Polynesians comparing them among themselves.  Then I compared the two groups to each other.

To those who are not familiar with Polynesian origins and/or are new to reading my blog, I will recap.  The ancestors of Polynesians originated from the Melanesia area and thrived there for thousands of years. Thousands of years later a group of “Austronesians” originating from Southeast Asia moved into the area, intermingled briefly and continued to move into western Polynesia where Polynesian culture was born.  At least a couple of thousand of years would pass before they would continue to expand further eastward.  As Polynesians moved from west to east, their genome became less diverse due to repeated founder’s effects and bottle necking.

oceania

I analyzed my mother’s results and compared her to a Hawaiian (orange), and a Maori (blue) below.  The Hawaiian is her top match, sharing a total of 693.60cM, longest block 15.52cM, consisting of 158 segments.  The Maori is her 4th top match sharing a total of 517.90cM, longest block 18.08cM, consisting of 119 segments.  FTDNA counts all the tiny segments as low as 1cM once the criteria of a match is met, which is why the number of segments is high.

tinyseg-mom

With the default at 5+cM I did not see anything unusual other than ordinary small segment matches.  But when I reduced the setting down to 1+cM (above), you can see a lot of tiny segments resembling a comb.  The slightly bigger gaps are just the missing teeth of a comb.  Some of these patterns begin to appear at 3+cM, although most do not appear until you reduce it down to 1+cM.  In my mother’s example above I show only chromosomes 1 – 20 since there were no segments that looked like a comb on the other chromosomes.

Then I looked at a Maori woman’s results (below) and compared hers to other Maoris and one Hawaiian.  She also shows the missing teeth at 1+cM, but only in a few areas.  Some areas have the comb pattern while other areas seem random.  The random segments could be IBS (Identical by State) or IBD (Identical by Descent).  Polynesians lack genetic diversity, particularly eastern Polynesians more than western Polynesians, so the random looking segments could be both IBS and IBD segments.

tinyseg-mary

Then I looked at two Tongan men and compared them to other Tongans and Samoans.  With Tongans & Samoans there seem to be more randomness.  A few of the tiniest segments may be close to each other, but nothing resembling too much like my mother’s results, a definite comb-pattern.  Take the purple and green colors for example for this one Tongan man below.  Notice how on some chromosomes they seem to be closer together while on others it just looks random.  Again, these are only using the bare minimum 1+cM.

tinyseg-peni

The other Tongan example.

tinyseg-keni

As you can see, it is hard to look for patterns that resembles a comb, and instead you see random colors all over the chromosomes.  What was interesting to see was how little X these Tongans had.  Unlike with the Maoris and Hawaiians, many of them shared multiple segments with each other.

But what does all of this mean?  These are very small island populations.  They have had repeated emigration from these small islands that resulted in a series of founder’s population.  There there was also bottle necking that occurred a few times.  All of these combined would leave only a few closely related ancestors to populate and repopulate new areas every time.

So the multiple, very small segments that represents a comb with missing teeth is the result of people descending from just a few ancestors who contributed that particular segment, but was inherited from multiple lines going back to the same ancestor over and over again.

Below is an image where I compare my mother with two Samoans (yellow & green) and three Tongans (orange, blue & purple).  There seems to be more randomness, however, there are a few of those comb patterns.

tiny-mom&western

Notice how the X chromosome is much more full, unlike what we saw when comparing the western Polynesians (Tongans & Samoans) among themselves. The yellow color belongs to a Samoan woman. The fact that women have 2 X chromosomes may be the reason why there is a long match versus using two Tongan men whose matches included two women in their examples above.  But these are Polynesians, so you would expect more of a match on the X.  My observance of matches for the past 2 years was limited to only my mother being compared to others, which means I have seen a lot of X matches for her, and the same for myself and my brother.

From what I am noticing so far is that these patterns look like what is mentioned in research papers about Polynesian genome and the loss of heterozygosity going from west to east.  The last place in Polynesia to be settled was in the east, ending at the extreme points of the Polynesian triangle, namely Rapa Nui (Easter Island) in the south east, Aotearoa (New Zealand) to the south west, and the Hawaiian islands in the north.  This explains why my mother and the Maori woman have less random looking tiny segments compared to the Tongans and Samoans.  And if we compare western and eastern Polynesians to each other, we may see some randomness but not as much as we would see with western Polynesians alone.  Other types of Polynesians getting DNA tested would help to exhibit any other additional patterns that I cannot currently see with the majority of Hawaiians and Maoris getting tested.

Loss of heterozygosity – from Western Polynesia to Eastern Polynesia

Genetic research on Polynesians will frequently mention the loss of heterozygosity.  This is more noticeable when comparing eastern Polynesians to western Polynesians.

oceania

Map outlining migratory paths of Austronesian speaking populations, including estimated dates. Adapted from Bellwood et al., (2011) “Are ‘Cultures’ Inherited? Multidisciplinary Perspectives on the Origins and Migrations of Austronesian-Speaking Peoples Prior to 1000 BC.” [doi: 10.137/journal.pone.0035026.g001

Polynesian populations are relatively homogenous both phenotypically and genetically. Over a span of 3,200 years they moved throughout the Pacific, and unlike in Europe and other large continents, they did not mix with other populations due to isolation.  These small founder populations have experienced several bottleneck effects, which further caused this loss of heterozygosity ending with the settlement of eastern Polynesia.  Polynesians’ lack of genetic diversity is less evident in western  Polynesia where initial settlement began.  Hawai’i, New Zealand and Easter Island are considered to be eastern Polynesia, and these places were the last places of Polynesia to be settled.

Recently I have been able to look at the autosomal matches among Samoans and Tongans of western Polynesia.  Previously, I have been only studying Hawaiian matches and noticed that top matches were both Hawaiians and Maori people.  Looking at Samoans and Tongans was very interesting as I now could compare the two different regions.

My mother is 80% Hawaiian, while I am 40%.  And as admixed as I am, I still get 1st – 3rd cousin predictions on Family Tree DNA (FTDNA), while on 23andme I get 2nd cousin and 3rd to distant cousin predictions.  The centimorgan totals that I show with my matches reach as high as 369cM on FTDNA, and 161cM on 23andme.  For my mother, 693cM on FTDNA and 376cM on 23andme.  I see the same happening with Maoris, ranging between 300cM – 700cM (FTDNA) for the top 20 people.  And for a non-admixed Hawaiian, their top matches are in the 600 – 700cM range.   An admixed Polynesian would logically have lower totals. But even an admixed person can still have a fairly high amount of totals shared, as when I am comparing myself being less than half Hawaiian.

When comparing two Tongans, the highest that they shared was 335cM.   A Samoan compared to another Samoan was 366cM.  And both of these Tongans and Samoans had their remaining top matches in the range of 100cM to 200cM.  Many of their matches are the same Hawaiians and Maori that match each other at a much higher total.  It is amazing to see these autosomal matches and how diverse the western Polynesians are, or rather how Hawaiians and Maoris are not as diverse.  And even if it is an admixed Hawaiian or Maori, the matches to each other are still pretty high, and as high as what non-admixed western Polynesians would have to each other.

When comparing the longest block (largest segment) with Tongans and Samoans, they seem to rarely get close to 15cM, averaging around 10cM.  Anything more than that could indicate a possible closer relationship or perhaps a specific common geographic origin.  The Hawaiians and Maoris usually range between 10cM – 15cM for the largest segment, but can go as high as 28cM which is usually in admixed Hawaiians and Maoris compared to each other.  In other words, all Polynesians in general will have high totals exceeding 100cM, but whose largest segment rarely exceeding 10cM.

I look forward to more western Polynesians getting tested so we can see if there is any pattern to specific islands in their own island group, something I have been trying to do with Hawaiians with the few haplogroups that there are for Polynesians.  What also needs to be analyzed are people from Tahiti and the Marquesas being that they were key dispersal points for eastern Polynesians.  I managed to only see the results of one admixed Tahitian woman and her match totals are identical to mine when comparing totals.  I am curious to find out what non-admixed Tahitians will show, if it is more identical to eastern Polynesians, or to western Polynesians.