Researchers Examine Ancient Stallions' Genetic Diversity

Researchers Examine Ancient Stallions' Genetic Diversity

The research team found that DNA samples from the Y chromosomes of horses living thousands of years ago were incredibly diverse compared to modern stallions' DNA.


Whoever says, "men are all alike," might also be able to say this about modern domestic stallions. According to new Y chromosome-specific DNA research on ancient horses, stallions were far more genetically diverse before humans domesticated them.

By sequencing DNA base pairs of the equine Y chromosome--the "sex chromosome" that is found only in males--geneticists have discovered that today's stallions have a surprising lack of diversity compared to many other species and to ancient wild horses. Because Y chromosomes are passed from sire to colt and never to fillies, the research provides an interesting view into paternal-line equine evolution over hundreds of years of domestication and breeding practices, according to Sebastian Lippold, PhD, researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

This revelation provides a previously unseen view of the scientific and cultural history of the horse.

"It shows how breeding practices could influence and shape genetic diversity and how different this can be between males and females," Lippold said.

In the pilot study on ancient Y chromosome sequencing in a population of any species, Lippold and his team studied DNA samples from the remains of horses living thousands of years ago (the oldest dating to more than 47,000 years) and compared these same sequences of codes for each Y chromosome. The team found that these codes in horses were incredibly diverse compared to modern stallions' DNA. Lippold based his findings on the results of a 2004 Swedish study that showed a particular DNA sequence in the Y chromosomes of 52 modern-day stallions representing 15 different breeds was absolutely identical.

This doesn't mean modern stallions have no diversity of all, Lippold cautioned. The researchers only studied one part of the Y chromosome, and the Y chromosome is only one of 32 chromosomes in the horse, so there is plenty of room for diversity in other genes.

The usefulness of looking specifically at the Y chromosome is in better understanding the "scientific history" of the horse, he said. "Also, the higher the diversity the less likely you are to run into inbreeding issues," Lippold said.

The study, "Discovery of lost diversity of paternal horse lineages using ancient DNA," will be published in an upcoming issue of Nature Communication. The abstract is available online.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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