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Genetic Linkage

DNA Study Adds Branch to North American Mammoth Family Tree

An international team has assembled billions of DNA snippets from molars that three mammoths left in the permafrost of northeastern Siberia, at widely different times. The research reveals an unrecognized ancestor that contributed half of the genome of the mammoth species that came to North America some 1.5 million years ago. The report appears in Nature.

 

The timescale of the study paints a portrait of mammoth evolution, perhaps even capturing a glimmer of speciation. The finding also sets back the clock of ancient DNA analysis; a horse that lived 780,000 to 560,000 years ago holds the record.

 

The three mammoth specimens were excavated in the 1970s from different locations in Siberia, dating from half a million to roughly 1.2 million years ago. They reside at the Geological Institute, Russian Academy of Sciences, in Moscow. The permafrost helped to preserve the DNA.

 

The Land Bridge Where It Happened

 

To continue reading, go to DNA Science, where this post first appeared.

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Extinction of the Woolly Rhino: Ancient Genomes Point to Climate Change, not Overhunting

Two views of the forces behind extinction of the woolly rhino elegantly illustrate how scientific thinking shifts to embrace new knowledge – a phenomenon that reverberates as new findings about COVID-19 pour in.

 

Several large animal species ("megafauna") vanished with the last ice age, including woolly rhinos and mammoths, huge armadillos, cave lions, and sabertooth tigers. The prevailing view of the extinctions blamed overhunting by humans, a scenario that once roughly fit broad timelines. But in a new report in Current Biology, DNA data from preserved rhinos open a window into the past onto climate change. The new view charts the ebb and flow of long-ago rhino populations, while identifying specific gene variants that flesh out how well the animals had been adapted to the cold – putting them at a disadvantage when the climate warmed.

 

It's interesting to contrast how different types of data support different conclusions.

 

To continue reading, go to my DNA Science blog.

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