Scientists don’t know much about what the very first mammal looked like, but they do know that it lived around 180-250 million years ago and that every mammal on Earth – from blue whales to platypuses – is descended from it.
New research has revealed the genome of this organism.
Scientists from around the world have computationally compiled a possible genome for the common ancestor of mammals using 32 genomes of living organisms.
This analysis covered a broad range of species from all three types, including bats pangolins, narwhals and humans for placental mammals and wombats and Tasmanian devils for marsupials.
As a non-mammal group, chickens and Chinese alligators were used.
Researchers reconstructed all 16 chromosomes from the common ancestor of all mammals. (A NodeThis is the last common ancestral line between two distinct genetic lines.
Researchers found that 38 chromosomes were present in the species of mammal at the beginning of the mammal tree’s phylogenetic tree.
It was shared NineThe smallest chromosomes are those that were shared with mammals, birds and reptiles’ common ancestor, which is an even further back in our tree.
“This astonishing finding shows the evolutionary stability in the order and orientation genes on chromosomes across a longer evolutionary timeframe of over 320,000,000 years.” SaysHarris Lewin is a senior author and evolutionary biologist.
These areas are often highly conserved and contain genes that play a role in the development of children.
The researchers looked at how chromosomes are broken down, combined, deleted or repeated over time.
The ‘Rearrangements-Affected Sections’ are the names given to the chromosomes.Breakpoints“, a rich source genetic variation that plays a part in the seperation of species through evolutionary processes.
The highest breakpoint rate was recorded when Therians – marsupial and placental mammals that give birth to live young – split from the egg-laying monotremes.
“Our results are important for understanding evolution of mammals and conservation efforts.” Says Lewin.
Most likely, the earliest mammal was a rat-like creature. MorganucodonIt lived about 200 million years ago, and it hatched eggs. Its fossil was found in a limestone crack in Wales in the UK, in 1949.
This genus can be referred to living mammals but not humans. It isn’t considered to be a common ancestorThis makes it a sister group with the mammal line.
Another sister mammalian clade is rodent-like Tritylodont genus. Fossils discovered in North America and Africa are too special to be common ancestors for all mammals. But they would have lived about the same time period as the first mammal genus.
This paper was published by theProceedings of the National Academy of Sciences.
