Centipedes have evolved complex venom five separate times
A team of researchers led by Dr. Ronald Jenner at the Natural History Museum and Eivind Undheim at the University of Oslo and the University of Queensland, have been unravelling the evolution of centipede venom. Through comparative proteotranscriptomic analysis they have discovered that centipedes have evolved complex venoms five separate times in the five different living orders of the group.
Centipedes are among the most ancient groups of venomous predatory land animals. Based on the current understanding of venoms in other groups, such as reptiles, the team had expected to find that the earliest centipedes would have already evolved complex venoms to catch their prey and defend against predators, but that turns out not to be the case.
To better understand the origin of centipede venom the team carried out ancestral state reconstructions.
Dr. Jenner explains, 'To our surprise centipede venom emerged as a simple toxin cocktail of about four components, and centipede venoms remained relatively simple cocktails for about the first 50 million years of centipede evolution.'
It appears that it was only after the five living orders of centipedes had split from each other that complex venoms evolved in parallel in the different orders.
'This degree of parallel evolution of complex venoms within a venomous group is unique and unexpected. We found that different centipede orders have completely different venoms, with no single component shared between all the orders. Hence, there is no such thing as ‘centipede venom’ as it depends entirely on what group of centipedes you are talking about.'
The study has raised more questions about the evolution of these unusual animals but for now these may be difficult to answer. Only one species Strigamia maritima of centipede has currently had its genome sequenced and analysis has shown that this species has lost all four components that were present in the ancestral centipede venom. In short very little can be learned from this species in terms of the evolution and origin of centipede venoms.
Dr. Jenner adds, ‘It turns out in this case that currently the most heavily studied species of the group is the most different from its ancestors, and therefore it can provide little informative about the evolutionary origin of the group. We hope that as more species are studied in greater detail we will be able to understand how this unusual example of parallel venom evolution occurred across the centipede orders.’
The study concludes that the evolution of the toxins that shape centipede venom arsenals are not concentrated in their early evolutionary history but are still happening frequently across the species.
The paper Parallel evolution of complex centipede venoms revealed by comparative proteotranscriptomic analyses is published in the journal of Molecular Biology & Evolution.
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