Bees survived dinosaur wipe out, they emerged over 120 million years ago

Bossert and associate professor Eduardo Almeida from the University of São Paulo, Brazil, worked with a diverse team to sequence and compare genes from over 200 bee species. 

To understand the bees' evolutionary history and distribution, they compared these genes with traits from 185 bee fossils and extinct species.

They conducted one of the most extensive genomic studies of bees ever done. For accuracy, hundreds to thousands of genes were analyzed simultaneously, ensuring their inferred relationships were reliable. 

"This is the first time we have broad genome-scale data for all seven bee families," said co-author Elizabeth Murray, a WSU assistant professor of entomology.

In previous studies, researchers discovered that the earliest bees evolved from wasps, transitioning from predators to gatherers of nectar and pollen.

This new research reveals that this transformation occurred in dry regions of western Gondwana during the early Cretaceous period.

As the continents formed, bees migrated northward, diversifying and thriving in tandem with flowering plants called angiosperms. Over time, they colonized India and Australia, expanding their global presence.

Interestingly, all major bee families appeared before the Tertiary period, around 65 million years ago, when dinosaurs went extinct. 

The researchers also found that the tropical regions of the Western Hemisphere have an incredibly diverse flora, likely influenced by their long association with bees.

Bees play a crucial role in the ecosystem, as one-quarter of all flowering plants belong to the extensive and varied rose family. These plants serve as essential hosts for bees, especially in tropical and temperate regions.

The team plans to continue studying more species of bees and their genetics and history. Future discoveries like these could help preserve pollinator populations and ensure our natural ecosystems' health.

"People are paying more attention to the conservation of bees and are trying to keep these species alive where they are," Murray said. "This work opens the way for more studies on the historical and ecological stage."

The complete study was published in Current Biology on July 27 and can be found here.

Study abstract:

Bees are the most significant pollinators of flowering plants. This partnership began ca. 120 million years ago, but the uncertainty of how and when bees spread across the planet has greatly obscured investigations of this key mutualism. We present a novel analysis of bee biogeography using extensive new genomic and fossil data to demonstrate that bees originated in Western Gondwana (Africa and South America). Bees likely originated in the Early Cretaceous, shortly before the breakup of Western Gondwana, and the early evolution of any major bee lineage is associated with either the South American or African land masses. Subsequently, bees colonized northern continents via a complex history of vicariance and dispersal. The notable early absences from large landmasses, particularly in Australia and India, have important implications for understanding the assembly of local floras and diverse modes of pollination. How bees spread around the world from their hypothesized Southern Hemisphere origin parallels the histories of numerous flowering plant clades, providing an essential step to studying the evolution of angiosperm pollination syndromes in space and time.