Around 120 million years ago, at the start of the Cretaceous period, groups of dinosaurs still walked the earth when the first bees appeared in what is currently South America and Africa, then connected as part of the Gondwana supercontinent. “The common ancestor of the bees probably appeared in the driest climate that this region had. To this day, the majority of the over 20,000 catalogued species prefer drier areas, where they are more diversified,” explained biologist Eduardo Almeida, from the Ribeirão Preto campus of the University of São Paulo (USP), while preparing to present the results about the evolution of bees at a workshop in the city of Portal, Arizona, USA, in mid-August.
Alongside German colleague Silas Bossert, from Washington State University, he led the study published in August in the journal Current Biology, which added more detail to the picture outlined in previous studies by using DNA sequence analysis of different parts of the genome of 216 bee species from all seven families and 28 subfamilies known today. The samples came from all continents except Antarctica (the only continent uninhabited by the bees), thanks to the data and specimens deposited in research museums — Almeida is the curator of the Prof. J. M. F. Camargo entomological collection, which houses hundreds of thousands of examples of bees.
The researcher compared genetic estimates of age and geographic distribution data of these species with information from 220 fossils and the locations where they were collected. All this information allowed the group to trace the family tree (phylogeny) of the bees, estimating the evolutionary kinship relationships between the main lineages and the ages of the evolutionary events. The result is a timeline that shows where and when the first species would have appeared and how the groups divided, diversified colors, shapes, behaviors, and modes of organization, and spread across the planet over time, following the rearrangement of the continents.
According to the results of the group from Ribeirão Preto, from the moment that the common ancestor of the bees emerged around 124 million years ago, a continuous process of diversification was influenced by the configuration of the continents at the time and the rise and fall of the sea level and the climate changes that took place during the different geological periods.
“The separation of the supercontinent led to a change in the configuration of how the bees were spread across the world,” says Almeida. The data suggest that, of the current seven families, only Melittidae did not already exist around 100 million years ago in the region which today corresponds to South America. Possibly because of this, the bees resisted the falling asteroid said to have been responsible for the mass extinction of the dinosaurs, in the Gulf of Mexico, around 60 million years ago. “They were already spread across the planet, in a distribution close to the current one,” ponders Almeida. He notes that, from this period on, some tropical environments began to expand to more elevated latitudes, which allowed the groups that lived in the tropical and subtropical regions in the Southern Hemisphere to advance towards North America, Europe, Asia, and North Africa.
Groups of bees probably reached Australia between 70 and 35 million years ago, with the first originating in South America and following a route crossing Antarctica, which connected the two continents to the south and had a milder climate than it currently does. Later, other bees that were already on the Asian continent would have also colonized Australia. They likely arrived in present-day India around 50 million years ago, after the territory — which had broken away from Gondwana prior to the origin of bees — collided with the Asian continent and met the local fauna.
The appearance of the ancestral bee is still unknown: would it have been large or small? Did it live in organized societies in hives or was it solitary? Almeida hazards a guess: it was probably solitary, since 85% of the species today have this type of habit, with their members living in individual burrows in the ground. Almeida has also been investigating means of reconstructing the ancestral morphology of these insects.
Adriana Tiba e Julio PupimA male of the Centris varia species on a guanhuma flower (Cordia superba) in Capão da Canoa, Rio Grande do SulAdriana Tiba e Julio Pupim
The notion that the bees appeared in the western part of Gondwana, which included South America and Africa, is not new. It was proposed by the US entomologist Charles Michener (1918–2015) back in 1979 in an article published in the journal Annals of the Missouri Botanical Garden.
Michener, Almeida’s academic “grandfather,” is a reference in the study of the evolution of bees and even spent a year in Brazil in 1956, working with Brazilian entomologist Jesus Santiago Moure (1912–2010), known as Father Moure, at UFPR in Curitiba. “Forty years later, the advance in genetic and computational analysis, besides the discovery of many bee fossils, allowed us to bring more evidence and new data for his hypothesis,” observes the researcher from Ribeirão Preto.
Biologist Vera Lucia Imperatriz Fonseca, from the São Paulo campus of USP, who did not participate in the study, observes that it is the broadest phylogenetic study of bees ever made. “In the past we used to study the bees in our backyard. Today, we can study the bees of the world,” she says, stressing the importance of preserving and expanding the country’s collection of insects, including bees, in order for this type of research to be expanded.
“The association between bees and flowers over the millions of years is another point that the work helps to think about,” says biologist Guilherme Cunha Ribeiro, of the Federal University of ABC (UFABC), who also did not participate in the study. In an article published in 2022 in the journal Cretaceous Research, Ribeiro and colleagues describe a new species of extinct wasp in the Crabronidae family, the fossil of which was located in the Crato Formation, in Nova Olinda, Ceará. Its age has been estimated at between 125 million and 115 million years.
“We argued that, if the Crabronidae family, considered by some studies as a sister of the bees, already existed in this time period, then the bees would have also existed,” says Ribeiro. As fossils of bees have not yet been found, despite the great abundance of insects already collected, he suggests that one of the explanations could be that they diversified further south on Gondwana.
Almeida explains that, at some point, carnivorous wasps became vegetarians, changing to feeding on pollen, and, after this, the bees appeared. “They became dependent on flowers and the main group responsible for pollination.” For this reason, one of the conclusions of the work coordinated by him is that the rich biodiversity of South American plants is related to the fact that this is the continent where bees have existed the longest. They took millions of years to establish themselves, adapt, and diversify. “If climate change radically transforms environments, we don’t know if they will be able to adapt,” he warns.
Projects
1. Phylogenomic systematics, comparative morphology, and biogeography of bees (Hymenoptera: Anthophila) (nº 18/09666-5); Grant Mechanism Regular Research Grant; Principal Investigator Eduardo Andrade Botelho de Almeida (USP); Investment R$144,943.60.
2. The paleoentomofauna of the Crato formation (lower Cretaceous; Araripe basin): systematics and paleoecology (nº 20/02844-5); Grant Mechanism Regular Research Grant; Principal Investigator Guilherme Cunha Ribeiro (UFABC); Investment R$63,301.40.
Scientific articles
ALMEIDA, E. A. B. et al. The evolutionary history of bees in time and space. Current Biology. vol. 33. pp. 1–14. aug. 21, 2023.
ROSA, B. B. et. al. The first crabronid wasps (Hymenoptera, Apoidea) from the Crato formation (Northeastern Brazil) and implications for the evolution of apoid wasps and bees during the Early Cretaceous. Cretaceous Research. vol. 137, 105248. Sept. 2022.
