The results of searching the family tree of the woolly mammoth have been surprising; it turns out the beasts we most closely associate with the Ice Age emerged not from a linear lineage, but a relatively complex web of genetic diversity.
A study examining 34 mammoth mitochondrial genomes, with specimens spanning a million years, gives us a glimpse of mammoth evolution. Mitochondrial DNA is a circular strand found in each cell’s powerhouse. It helps researchers trace lineage on the maternal side and is useful to paleontologists because it resists breaking down, unlike less hardy genetic material.
Researchers studied mammoth mitochondrial DNA from as far back as 1.3 million years, with the most recent based on genetic material from a relatively recent mammoth from about 125,000 years ago. The study, published in Molecular Biology and Evolution, describes mammoth evolutionary history over a million years.
Genetic Diversity of the Woolly Mammoth
“Our analyses provide an unprecedented glimpse into how major deep-time demographic events might have shaped the genetic diversity of mammoths through time," J. Camilo Chacón-Duque, a researcher at Stockholm University and an author of the study, said in a press release.
Although biodiversity likely evolved over the past 2.5 million years, very few DNA samples older than 100,000 years have been preserved well enough to study. That gives scientists the equivalent of one short scene to watch from a long-running television series.
Recovering DNA from mammoths as old as a million years, analyzing it, then comparing it to 200 previously published mammoth mitogenomes essentially gives researchers a pretty good sample of scenes over its entire run.
Read More: A Freeze-Dried Woolly Mammoth Yields 52,000-Year-Old Chromosomes
Major Demographic Shifts
The analysis showed that genetic changes in mammoth genomes matched well with major demographic shifts that occurred during the Early and Middle Pleistocene. The study supports an ancient Siberian origin for major mammoth lineages. And the article discusses how shifts in mammoth population in different parts of the world might have resulted in a variety of mammoth genomic subtypes.
For instance, the team identified the oldest known mammoth DNA in North America, dating back 200,000 years from a specimen found in the Yukon Territory of Canada. And the research confirms previous work showing that mammoths from around a million years ago are vastly different than the most recent version of the creatures.
Read More: Where Woolly Mammoths Roamed, Humans Trailed Close Behind
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Molecular Biology and Evolution. A Million Years of Mammoth Mitogenome Evolution
Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
