December 7, 2023

Increased Homozygosity Linked to Decreased Fertility in Human Population, Study Reveals

A recent study conducted by researchers from the University of California, Davis, has provided direct evidence of the negative effects of increased homozygosity on fertility in human populations. The findings, published in the Proceedings of the National Academy of Sciences journal, shed light on the consequences of inbreeding within isolated communities.

The research focused on Namibia’s Himba community, an agro-pastoralist population known for their unique marriage and reproduction practices. In this community, individuals often marry partners from within the same group, leading to a higher likelihood of shared ancestry. The researchers studied 681 individuals from the Himba population to analyze the genetic markers associated with inbreeding.

The study revealed that the Himba population showed higher levels of homozygosity, indicated by long runs of homozygosity (ROH) in their genomes. These ROH markers suggest that the individuals’ parents were likely to have had a common ancestor. Interestingly, none of the individuals in the sample population had parents who were first cousins, highlighting the complexity of genetic inheritance and the accumulation of inbreeding effects over time.

The researchers discovered that inbreeding events, such as population bottlenecks, can have genetic echoes that manifest generations later. The analysis indicated that these events occurred within the past 12 to 18 generations of the Himba population, highlighting the long-term effects of inbreeding on genetic diversity.

To assess the impact of long ROH on fertility, the researchers measured the reproductive success of post-reproductive women in the sample population. Their reproductive success was defined as the number of children who survived until at least the age of 5. Statistical models were employed to analyze the relationship between the proportion of the genome in ROH and the number of children a woman had.

The findings showed a clear correlation between increased homozygosity and decreased fertility. Women with a higher proportion of the genome in ROH were more likely to have fewer children throughout their lifetimes compared to women with less ROH. This suggests that individuals with more closely related parents have a higher risk of reduced fertility.

The study highlights the importance of genetic diversity in maintaining healthy populations. Inbreeding, which leads to increased homozygosity, can have detrimental effects on fertility and potentially compromise future generations. Understanding the consequences of inbreeding and its impact on evolutionary fitness is crucial for designing appropriate interventions and promoting genetic diversity within populations.

The research conducted by the University of California, Davis, provides valuable insights into the effects of increased homozygosity on fertility in human populations. By studying the Himba community in Namibia, the researchers have demonstrated the long-term consequences of inbreeding and the importance of genetic diversity in maintaining healthy populations. The findings contribute to our understanding of the complex relationship between genetics and fertility and highlight the need for further research in this area.

1. Source: Coherent Market Insights, Public sources, Desk research
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