Bee evolution occurred tens of millions of years earlier than previously believed

A new study has revealed that bee evolution predates previous estimates by tens of millions of years.

A team of researchers hailing from Washington State University (WSU) and the University of São Paulo, Brazil, have successfully traced bee genealogy back a staggering 120 million years. They evolved on an ancient supercontinent known as Gondwana, encompassing the present-day continents of Africa and South America.

This study presents an unexpected and comprehensive history of bee evolution, demonstrating that the creatures not only originated much earlier but also diversified at a faster pace and spread over larger territories than was previously believed. These findings, published in the eminent journal Current Biology, reshuffle our understanding of bee evolution.

Assistant professor with WSU’s Department of Entomology, Silas Bossert, stated, “There’s been a longstanding puzzle about the spatial origin of bees.” Bossert, alongside Eduardo Almeida, an associate professor at the University of São Paulo, spearheaded this research project.

How bee evolution was studied

In this extensive effort, the researchers worked closely with collaborators from around the globe to gather samples and conduct computational analyses. Over 200 bee species were scrutinized, their genes sequenced and compared.

Their traits were then weighed against 185 different bee fossils and extinct species. This detailed effort resulted in an evolutionary map and genealogical models depicting historical bee distribution.

In a notable achievement, the team undertook what could arguably be the most extensive genomic study of bees, analyzing hundreds to thousands of genes simultaneously to ensure the accuracy of the relationships inferred.

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

Bees originated in Gondwana

Previously, studies had established that the first bees likely evolved from wasps, transitioning from being predators to collectors of nectar and pollen. However, the current research indicates that bee evolution began in the arid regions of western Gondwana during the early Cretaceous period.

Bossert clarified, “For the first time, we have statistical evidence that bees originated on Gondwana,” adding, “We now know that bees are originally southern hemisphere insects.”

As the continents began to form, the researchers discovered evidence of bees moving north, diversifying and spreading in sync with the evolution of angiosperms, or flowering plants. The bees then colonized areas like India and Australia.

Bee evolution happened as dinosaurs were vanishing

Furthermore, it appears that all major families of bees diverged before the onset of the Tertiary period, 65 million years ago — a time when dinosaurs became extinct.

According to the authors, the rich flora of the western hemisphere’s tropical regions may owe its diversity to the prolonged interaction with bees. Notably, the rose family, which comprises a significant proportion of the tropical and temperate host plants for bees, makes up a quarter of all flowering plants.

The team, led by Bossert, intends to continue exploring the history and genetics of more bee species. These findings are a critical first step in understanding the co-evolution of bees and flowering plants. Moreover, gaining insight into how bees spread and adapted to their current ecological niches could aid efforts to maintain healthy pollinator populations.

“People are paying more attention to the conservation of bees and are trying to keep these species alive where they are,” Murray noted. “This work opens the way for more studies on the historical and ecological stage.” This research, therefore, not only redraws our understanding of bee evolution but also paves the way for essential conservation work in the future.

More about bees

Bees are flying insects closely related to wasps and ants, known for their role in pollination and. Also, in the case of the best-known bee species, the European honey bee, for producing honey and beeswax. They belong to the vast order of insects called Hymenoptera, which also includes ants, wasps, and sawflies.

Bee evolution and classification

Over 20,000 species of bees inhabit every continent except Antarctica, specifically in habitats containing insect-pollinated flowering plants.

The diversity of bee species is broad, ranging from the tiny stingless bee species to the large carpenter bees. Scientists classify bees into seven recognized biological families. The Apidae family includes well-known species like the honey bee and bumblebee.

Anatomy

The anatomy of a bee comprises three primary body parts: the head, thorax, and abdomen. The head houses antennae for sensing their environment, and compound eyes for vision.

The thorax carries the wings and legs, and the abdomen contains the digestive and reproductive organs. Many species possess a stinger for defense.

Diet

Bees primarily feed on nectar and pollen, the former for energy and the latter for protein and other nutrients. This diet, rich in sugar, aids in the high-energy flight and body temperature regulation.

Life cycle

The bee life cycle consists of four stages: egg, larva, pupa, and adult. The queen bee lays the eggs that hatch into larvae, and worker bees care for them. Larvae metamorphose into pupae and finally emerge as adult bees.

Social structure

Bees exhibit a range of social structures. Honey bees, for example, live in complex, highly organized colonies. They are led by a queen and serviced by thousands of worker bees. Conversely, many species are solitary, with individual females living and breeding independently.

Role in the ecosystem

Bees are key pollinators. They transfer pollen from the male parts of a flower to the female parts. This facilitates the reproduction of many plant species. They play a crucial role in the global ecosystem and human agriculture, with their decline posing serious threats to biodiversity and food security.

Threats and conservation

Bees face numerous threats, including habitat loss, pesticide exposure, disease, and climate change. These factors have led to declines in bee populations worldwide.

In response, conservation efforts aim to protect and enhance bee habitats, limit pesticide use, and raise awareness about their importance.

Cultural significance

Bees hold a significant place in human culture, symbolizing various attributes like industriousness, loyalty, and bravery in different societies. Their products, such as honey and beeswax, have been used for food, medicine, and crafting materials since ancient times.

Bees are an integral part of our natural world. They are crucial to the survival of many plant species and play a vital role in human food production. Understanding and protecting these industrious insects is key to preserving biodiversity and maintaining our ecosystems.