Metamorphosis Drives Insect Evolution: Butterflies May be Less Likely to Become Extinct

Insects have the potential to change quickly, as far as evolution goes. Now, though, scientists have found that there's one set of insects that speed ahead more quickly than the others. It turns out that metamorphosing insects diversify far more quickly than other insects, and are the biggest contributors to the evolution of insect diversity.

In this case, the researchers used a complete fossil catalogue that showed the timescales of origination and extinction of different families of insects. In all, they collated a database of 1,500 fossil families, a third of which were entirely new to the record since 1993. By updating this fossil record, the researchers found that families of insects that undergo metamorphosis, like butterflies, were less prone to extinction.

Insects that undergo metamorphosis include a pupal stage that separates two different juvenile and adult stages. Insects that undergo metamorphosis include moths and butterflies, beetles, wasps, bees, ants and true flies. These insects display a greater turnover of species and therefore have a higher rate of diversification, which means that they're huge drivers of evolution.

"I have been working on the evolutionary reasons for insect diversity for over a decade," said Peter Mayhew, one of the researchers, in a news release. "An important task is to pin down in which groups of insects the rates of diversification or extinction have changed, and which are therefore responsible for most of their richness. Intuitively, people have long suspected that insects with metamorphosis have experienced different rates of diversification, because the richest insect orders mostly have metamorphosis."

The new datasets reveal that metamorphosis is important for insect evolution. Why this is, though, is another question that scientists hope to answer in the future.

"Metamorphosis might reduce extinction, and promote speciation, in a number of different ways," said Mayhew. "It might reduce competition between larvae and adults, it might promote dietary specialization, it might reduce development times, it might improve survival in times of hardship, or something else. Future work needs to address this question."

The findings are published in the journal Proceedings of the Royal Society B: Biological Sciences.