Venomous animals diversify at double the rate

In a new study from Swansea University, experts are describing how venom has contributed to the species diversity of insects and fish. The researchers found that venomous animals diversify twice as fast as non-venomous animals. 

Insects and fish have a larger number of species than any other groups in the animal kingdom. Scientists have identified over one million species of insects, and 31,269 species of fish. 

Overall, 16 percent of all insect families and ten percent of fish families contain venomous species, such as wasps or stingrays. The new study has revealed that venom has evolved independently at least 19 times in fish and at least 28 times in insects throughout their evolutionary history.   

Venom helps animals to repel predators and catch prey. This may allow venomous animals to exploit more opportunities in their environment, potentially leading to the formation of new species as they diversify in their ecology, explained the researchers.

The study is one of the first to examine the role of venom in driving biodiversity. By finding that venom has evolved so many times, and that it is associated with faster diversification, the research indicates that venom has played an important role in promoting species diversity.

“Our results provide evidence that venom has played a part in generating the diversity of insects and fishes, which have the largest number of species amongst invertebrates and vertebrates respectively,” said study lead author Dr. Kevin Arbuckle.

“Venom is not the only factor driving species richness in these animal groups, but we show that it has played an important but previously unrecognised role in generating the amazing diversity we see today amongst insects and fishes.”

Among insects, venom evolved fairly evenly over time. In fish, however, most venomous species can be traced back to the Late Cretaceous and Eocene periods.

“Mosasaurs – the aquatic behemoths made famous in the Jurassic World series – originated and peaked in diversity in the Late Cretaceous, at a time when other large marine predator groups were declining,” explained Dr. Arbuckle.

“Similarly, whales originated and peaked in diversity in the Eocene, when most other large marine predators had gone extinct at the end-Cretaceous mass extinction, which killed off the dinosaurs.”

“Both early whales and mosasaurs are thought to have been active predators with similar styles of movement. As a result, we cautiously speculate that most origins of fish venom were linked to similar predation pressures imposed by mosasaurs in the Late Cretaceous and early whales in the Eocene.”

The study is published in the journal BMC Ecology and Evolution.

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By Chrissy Sexton, Earth.com Staff Writer