Sequence variation of the human Y chromosome

Area of Science:

• Genomics
• Human Evolution
• Population Genetics

Background:

• The Y chromosome, inherited paternally, and mitochondrial DNA, inherited maternally, offer distinct perspectives on human evolutionary history.
• Understanding the evolutionary dynamics of the Y chromosome is crucial for reconstructing past human migrations and population structures.

Purpose of the Study:

• To sequence and analyze the nonrecombining portion of the Y chromosome (NRY) in early-branching human lineages and a common chimpanzee.
• To compare the evolutionary patterns and coalescence times of the Y chromosome with those of the mitochondrial genome.

Main Methods:

• Generated over 100 kilobases of sequence data from the NRY of five humans and one chimpanzee.
• Selected human subjects representing the earliest branches of the human mitochondrial tree.
• Analyzed sequence divergence and estimated coalescence times between human and chimpanzee Y chromosomes, and within the human Y chromosome sample.

Main Results:

• Detected minimal sequence variation (three substitution sites) within the human Y chromosome sample.
• Observed a 1.3% sequence divergence between human and chimpanzee Y chromosomes.
• Estimated a more recent coalescence time for the Y chromosome compared to the mitochondrial genome.

Conclusions:

• The recent Y chromosome coalescence time suggests a potential selective sweep of an advantageous Y chromosome or significant male-mediated migration events in recent human history.
• These findings provide a new perspective on human population genetics, highlighting the distinct evolutionary trajectories of paternal and maternal lineages.