The not so popular Australian mammal, the platypus, has been a mystery to scientists since its discovery. New research may finally hold the key to understanding one of the few mammals that lay eggs.
(Photo : Frederick Polydore Nodder / Wikimedia Commons)
This illustration by Frederick Polydore Nodder is the first published illustration of a platypus. It accompanied George Shaw’s 1799 description of the animal in the Naturalist’s Miscellany, or Coloured figures of natural objects”. London:Nodder & Co.
Can Mammals Lay Eggs?
Commonly called platypus, the Ornithorhynchus anatinus is a carnivorous mammal with a swiftly decreasing population.
It is among the most unlikely animals leading scientists who first discovered the animal to doubt its authenticity. The mammalian specimen can only be described as an assortment of familiar species: it has a duck-like bill and webbed feet, a beaver’s tail, an otter’s fur, and body males carry sharp venomous stingers on the heels of their feet.
Truly a remarkable specimen, platypus can live, hunt, and thrive in both land and water.
It is classified under the mammalian group monotremes, which include echidnas. It is a specialized egg-laying predatory group that has been the center of research for decades.
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How Platypus Genomes Could Reveal New Evolutionary Information
A recent study published in the journal Nature, gives a first look at the complete overview of the platypus’ genome revealing new evolutionary information about the mysterious mammalian group and insight on human DNA.
Monotremes, which only include the semi-aquatic platypus and echidnas, share a unique trait: egg-laying.
For the first time since its discovery, scientists are able to provide a complete chromosomal map of the platypus and a lee-complete echidna genome-map.
Using genetic data, scientists analyzed the species habits, from eating habits to swimming routines. One of the discoveries pertains to the mammals’ olfactory, which has far fewer genes than the terrestrial counterpart: the echidnas.
The genetic data gathered also reveals that when platypus are submerged, their nasal cavity and eyes are closed solely relying on other senses suck as electric stimuli for prey detection.
Unique Reproductive Strategy
Egg-laying is by far the most unique in the species. Hence scientists focused explicitly on sex chromosomes. The monotreme has 5 X chromosomes and 5 Y chromosomes, for a total of 10 sex chromosomes.
Humans, on the other hand, have only 2 sex chromosomes.
Researchers have discovered more significant similarities between birds and platypus than between humans and platypus through careful analysis.
Guojie Zhang, the author and a biology professor at the University of Copenhagen, tells in an interview, “Genome sequencing, we found 10 sex chromosomes do not have any homolog with the X/Y chromosomes in humans.”
The complex structure of the platypus’ sex chromosomes displays unusual interaction during cell division (meiosis). Due to the interaction and pairing of chromosomes during meiosis in monotremes, the sex chromosomes can form ring structures, according to Zhang.
The study’s most intriguing findings are regarding the ring structure since the chromosomal structure is often seen in plants but never in animals, making it a groundbreaking discovery.
Comparing platypus genomes to other ancient animals, scientists could map out the ancient mammal’s chromosomes. The research was also able to trace the last common ancestors of humans and platypus dating back to 163 to 191 million years ago.
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