Most of world's biodiversity can be traced to 'rapid expansions' in few big group of species: Study

New Delhi, Aug 21 (PTI) Majority of the world's biodiversity evolved through a few big groups of species that grew and diversified at an exceptionally rapid pace, a study has found.

Researchers from the US analysed the rates of richness and diversification of species across 'clades' -- groups of multiple species, each of which evolved from a single ancestor.

"Specifically, if we look among the kingdoms of life, among animal phyla (ancestor), and among plant phyla, we find in each case that more than 80 per cent of known species belong to the minority of groups with exceptionally high rates of species diversification," said John J Wiens, a professor at the University of Arizona, US, and a co-author of the study published in the journal Frontiers in Ecology and Evolution.

The authors said it is considered that a few groups among each species tend to predominate -- for example, more than 40 per cent of living insects are beetles, while 60 per cent of birds are passerines (including sparrows), and more than 85 per cent of plants are those that bear flowers.

However, it is not known if such a concentration of species within a few exceptionally large groups is universal to all of life on Earth -- a question that is important for understanding evolution and ecology, the researchers said.

"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," Wiens said.

The team looked at nearly five million species of plants and animals, including 678 families of land plants, 870 families of insects, 12 classes of vertebrates, along with 17 kingdoms and 2,545 families across all of life.

The authors wrote, "We find that among the major clades of living organisms and among land plant phyla and animal phyla, (more than) 80 per cent of known species richness is contained within the few clades in the (top 10 per cent of) diversification rates in each group." Wiens said the results, combined with those from previous studies, also "suggest key traits that might explain these rapid radiations".

"These traits include multicellularity in plants, animals and fungi across the kingdoms of life; the invasion of land and the adoption of a plant-based diet in arthropods (a type of invertebrate) among animal phyla; and the emergence of flowers and insect pollination in flowering plants among plant phyla," the co-author said. PTI KRS KRS KSS KSS