The last population of woolly mammoths on Wrangel Island faced extinction 10,000 years ago when rising sea levels cut them off from the Siberian coast. It was initially thought that in-breeding caused by this isolation led to their demise. However, a new genetic analysis published in Cell challenges this theory.
Contrary to expectations, the study found that there was a relative lack of harmful genetic mutations in the mammoth population on Wrangel Island. This was surprising, as a previous study had suggested that harmful mutations may have accumulated over time. The population, starting from fewer than 10 individuals, grew to 200-300 mammoths over 6,000 years and 20 generations.
The genetic analysis revealed that two genetic forces, natural selection, and genetic drift, were at play in the mammoth population. Natural selection works to eliminate harmful mutations, while genetic drift preserves mutations across generations, particularly in smaller populations like the one on Wrangel Island.
Despite the competition between natural selection and genetic drift, it seems that the mammoths were not wiped out by inbreeding. Other factors such as disease outbreaks, tundra fires, or short-term climatic changes could have played a role in their extinction. This highlights the delicate balance of factors that can lead to a species’ demise.
The implications of this genetic study extend to conservation efforts today. By understanding how natural selection and genetic drift interact in small populations, conservationists can better plan strategies to preserve endangered species. For instance, moving a few individuals between isolated populations can help slow genetic drift and maintain genetic diversity.
While the study authors have yet to analyze DNA from the most recent Wrangel Island mammoths, fossils from the last 300 years of their existence are being studied. This ongoing research will provide further insights into the genetic factors that contributed to the extinction of these iconic creatures.
In conclusion, the genetic analysis of the last mammoth population on Wrangel Island sheds light on the complex interplay between natural selection and genetic drift in small populations. By learning from the past, we can better inform conservation efforts and ensure the survival of endangered species in the future.
