First Close Relative for Haas and Zolder lines

A close match appeared at Family Tree DNA among my maternal uncle's matches.  This is the first close match from his father's side of the family.  The common ancestors are Samuel Haas (1867-1945) and Mary Zolder (1870-1948).

Use of a full name is encouraged at Family Tree DNA.
Unlike 23andMe, FamilyTreeDNA testers do not have to "consent to share genomes" to view the matching DNA segments,
while AncestryDNA does not show shared segments.

The only information about this match is his name, email address, and the amount and location of identical DNA.  This was enough to figure out how he is related to my uncle:  they are first cousins, once removed.  This cousin is the generation after my uncle, though my uncle is younger than this cousin.

Family Finder Chromosome Browser

Here is a graph that Family Tree DNA can create for a physical representation of the identical segments shared by relatives, called a Chromosome Browser.  (23andMe also creates such graphs.  AncestryDNA does not.)

The orange lines are the segments shared by my uncle and his first cousin on his mother's side of the family- ODonnell and Preston.  The blue lines are the segments my uncle shares with the first cousin, once removed, from his father's side- Haas and Zolder.

Note that in some areas, such as chromosome 11, that both cousins appear in the same areas.  This is because every person has two pairs of chromosomes numbers 1 through 22.  One came from the mother; the other from the father.  Current DNA analysis does distinguish which side the segment is on.

For distant DNA cousins, usually only one or two segments are shared.  Other people will often share the same spot on a chromosome.  If they do not match each other, this means that one is from the mother's side and the other from the father's side.  (Unless the segments are too small to report, or there is an error in reading the DNA in that spot.)

Samuel Haas and Zolder were from what is now Slovakia.  They spoke German.  There do not seem to be many of their relations in the DNA matches of my uncle.  Family Tree DNA provides and "in common with" tool.  Out of the 400+ matches to my uncle, only three also match his new close paternal cousin.  In comparison, seventy matches are shared by my uncle and his maternal first cousin on their common Irish lines.  Certain populations are more numerous than others in the DNA databases.