lobal Patterns of Human Variation

PATTERNS

1. Higher Genetic Diversity in Africa:

2. Implications for Human Evolutionary History:

3. Linkage Disequilibrium (LD):

   1. SNP Studies:

Higher Genetic Diversity in Africa:

• Older Populations: African populations

• have accumulated mutations over ~200,000 years,

• Higher Genetic Diversity in Africa:

  • Older Populations:

    • non-Africans

• descend from a smaller founder group that migrated ~60,000–70,000 years ago, creating a bottleneck.

Higher Genetic Diversity in Africa:

• No Severe Bottleneck: AFRICANS

• Larger, more stable populations

• maintained greater diversity

• Higher Genetic Diversity in Africa:

  • No Severe Bottleneck:

    • non-Africans, who

• underwent repeated founder effects.

1. Implications for Human Evolutionary History:

• Supports the "Out of Africa" model,

• Reflects longer demographic history

1. Implications for Human Evolutionary History:

   • Supports the "Out of Africa" model, as

• all non-African populations show subsets of African genetic diversity.

1. Implications for Human Evolutionary History:

   • Reflects longer demographic history

• in Africa, with sustained large population sizes.

1. Linkage Disequilibrium (LD):

• Low LD in Africans:

• High LD in Non-Africans:

1. Linkage Disequilibrium (LD):

   • Low LD in Africans:

• Due to older populations and more recombination events breaking up haplotype blocks.

• High LD in Non-Africans:

• Result of recent bottlenecks (e.g., migration out of Africa), reducing recombination opportunities.

1. SNP Studies:

• Private SNPs:

• Shared SNPs:

• Private SNPs

• : Rare in non-Africans, consistent with recent expansion from a small founder group.

• Shared SNPs:

• Most alleles exist globally but at differing frequencies, undermining the concept of biologically distinct "races."

Key Evidence:

• Higher heterozygosity in African genomes.

  • Gradual decline in diversity with distance from Africa, matching migration routes.