Most known species evolved during 'explosions' of diversity, shows first analysis across 'tree of life'

tomwt — Wed, 20 Aug 2025 16:02:33 +0000

Most known species evolved during 'explosions' of diversity, shows first analysis across 'tree of life' tomwt Wed, 08/20/2025 - 09:02 More CNAS in the Media Michiel Dijkstra | Frontiers August 19, 2025

FRONTIERS - The British evolutionary biologist JBS Haldane is said to have quipped that any divine being evidently had ‘an ordinate fondness for beetles’. This bon mot conveyed an important truth: the ‘tree of life’ – the family tree of all species, living or extinct – is very uneven. In places, it resembles a dense thicket of short twigs; elsewhere it has only sparse but long branches. A few groups tend to predominate: as Haldane pointed out, more than 40% of extant insects are beetles, while 60% of birds are passerines, and more than 85% of plants are flowering plants.

But is such a concentration of species within a few exceptionally large groups a universal phenomenon of life on Earth? This question, important for our understanding of evolution and ecology, has long been the subject of controversy among biologists. But until recently, it was difficult to answer due to our poor knowledge of the number of species in existence, their evolutionary relationships, and the age of each group. But now, scientists in the US finally have provided an answer, published in Frontiers in Ecology and Evolution.

“Here we show for the first time that most living species do indeed belong to a limited number of rapid radiations: that is, they form groups with many species which evolved in a relatively short period of time,” said Dr John J. Wiens, a professor at the University of Arizona.

“Specifically, if we look among the kingdoms of life, among animal phyla, and among plant phyla, we find in each case that more than 80% of known species belong to the minority of groups with exceptionally high rates of species diversification.”

Wiens and his co-author Dr. Daniel Moen, an assistant professor at the University of California Riverside, here analyzed the distribution of species richness and diversification rates across ‘clades’ – groups of species that each evolved from a single ancestor, such as phyla, classes, or families.

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