The evolutionary tree of elephants has been rewritten
Elephants and mammoths engaged in interspecific interbreeding
The extraction of DNA from the remains of long-extinct animals has forced scientists to reconsider their views on the evolutionary history of elephants.
Modern elephants are divided into three species: the Indian elephant (Elephas maximus) and two African elephants – forest (Loxodonta cyclotis) and savanna (Loxodonta africana). The division of African elephants, originally considered a single species, was finally confirmed only in 2010.
According to the fossil finds, scientists assumed that the ancestor of the current Indian elephants was a straight-tusked elephant (Paleoloxodon antiquus), which lived in Europe and became extinct about 100 thousand years ago.
Straight-tusked elephant, reconstruction (Wikimedia Commons)
However, genetic analysis showed that the straight-tusked elephant was closer to African elephants, and more to forest than to savanna. Also, geneticists have found that in the past, various elephants have crossed with mammoths more than once.
The discovery was announced at the Seventh International Symposium on Biomolecular Archaeology in Oxford. The team of scientists who studied the genome of the straight-tusked elephant was led by evolutionary geneticist Eleftheria Palkopoulou and population geneticist David Reich from Harvard Medical School, as well as Michael Hofreiter from the University of Potsdam. DNA samples were extracted from two 120,000-year-old tusks found in Germany.
Palkopoulou and her colleagues also demonstrated the genomes of other extinct animals, including four woolly mammoths (Mammuthus primigenius) and, for the first time in history, complete genomic sequences of the Columbus mammoth (Mammuthus columbi) and two American mastodons (Mammut americanum). Researchers have found evidence that many of these species interbred. Straight-tusked elephants interbred with both Indian elephants and mammoths. Two species of African elephants, hybrids of which are still known in some areas of the Democratic Republic of the Congo, seem to have interbred in the distant past. Palkopoulou and her colleagues hope to establish when these crosses took place.
The genome of straight-tusked elephants, sequenced by scientists, did not set a record of antiquity. It belongs to DNA from horse remains between 560000 and 780,000 years old, which were found in permafrost in the Canadian Arctic. But these samples were the oldest of those isolated from the remains that were in a warm climate. A few years ago, this seemed impossible, so the story of the study was greeted with awe by scientists.
If you are OK with a sense of humor, you can listen to the musical commentary on this news – VM.
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20.09.2016