A collaborative effort between Mexican and European researchers has sparked interest in exploring the DNA of the Columbian mammoth beyond its widely known range, which extended into Central America. The focus has shifted to the Basin of Mexico, an area significantly south of the known habitats of woolly mammoths. Despite the warmer climate typically accelerating DNA degradation, the research team benefitted from an abundance of mammoth bones. Over the centuries, extensive construction in the Basin has unearthed numerous remains, with over 100 individual mammoths identified during the construction of Mexico City’s international airport.
The researchers concentrated exclusively on the mitochondrial genome, which offers advantages in degraded environments. Unlike the two sets of chromosomes contained in each cell, mitochondrial DNA exists in hundreds of copies within the many mitochondria present in a cell. While this smaller genetic material may lack depth in ancestral details, it is more likely to remain intact in sufficient quantities for analysis.
Ultimately, the team’s efforts paid off, yielding 61 new mitochondrial genomes from Columbian mammoths in Mexico out of 83 analyzed samples, with 28 being of high enough quality for further research.
A Unique Genetic Heritage
Using the acquired genetic data to construct a family tree alongside samples from other Columbian and woolly mammoths, the researchers aimed to elucidate the relationships among various populations. Early results revealed an intriguing position on that tree for the Mexican mammoths.
Notably, the samples clustered closely together, forming a distinct block with three sub-groupings within it. However, the placement of this block raised questions; woolly mammoths flanked it on either side, suggesting that the lineage might be a branch off the woolly mammoth lineage. This scenario could be expected if all Columbian mammoths were grouped cohesively with their Mexican counterparts. However, findings indicate that some Columbian mammoths from farther north are actually more closely related to woolly mammoths than to their Mexican relatives.
