Population genetic implications from sequence variation in four Y chromosome genes

Area of Science:

• Human evolutionary genetics
• Population genetics

Background:

• The Y chromosome plays a crucial role in human evolution and population studies.
• Understanding genetic diversity within Y chromosome genes provides insights into past population dynamics.

Purpose of the Study:

• To analyze genetic variation in four Y chromosome genes (SMCY, UTY1, DBY, DFFRY).
• To investigate patterns of human population growth and expansion using Y chromosome genetic data.

Main Methods:

• Genomic sequencing of SMCY and UTY1 genes.
• Primer walking to complete UTY1 sequencing.
• Denaturing HPLC to screen for polymorphic sites across continents.
• Analysis of nucleotide diversity and allele frequencies.

Main Results:

• Identified 98 variants across SMCY, UTY1, and DFFRY; DBY showed no variants.
• Nucleotide diversity estimates for coding regions ranged from 2.45 x 10(-5) to 8.54 x 10(-5).
• Noncoding regions exhibited 2- to 3-fold higher diversity (9.16 x 10(-5) to 14.2 x 10(-5)).
• Allele frequency distributions supported exponential population growth, not a constant population model.
• Pairwise mismatch distributions estimated population expansion ~28,000 years ago.

Conclusions:

• Genetic data from Y chromosome genes support a model of exponential human population growth.
• The estimated timing of population expansion correlates with the Aurignacian period and Neanderthal decline.
• Y chromosome gene sequencing is a valuable tool for reconstructing human evolutionary history.