Corbiculate bees (IMAGE) Entomological Society of America Caption A new study has mounted perhaps the most intricate, detailed look ever at the diversity in structure and form of bees, offering new insights in a long-standing debate over how complex social behaviors arose in certain branches of bees' evolutionary tree. Published today in Insect Systematics and Diversity, the report is built on an analysis of nearly 300 morphological traits in bees, how those traits vary across numerous species, and what the variations suggest about the evolutionary relations between bee species. The result offers strong evidence that complex social behavior developed just once in pollen-carrying bees, rather than twice or more, separately, in different evolutionary branches--but researchers say the case is far from closed. The bee varieties studied were all "corbiculate" bees--those that possess corbicula, or pollen baskets, on their hind legs--which encompass honey bees, stingless bees, bumble bees, and orchid bees. Examples of bee species analyzed include (clockwise from top left) Apis dorsata, a member of the honey bee tribe Apini; Bombus pauloensis, of the bumble bee tribe Bombini, Melipona quadrifasciata, of the stingless bee tribe Meliponini, and Exaerete smaragdina, of the orchid bee tribe Euglossini. Note: Images are not to scale. (Photos by Eduardo Alemeida, Ph.D., University of São Paulo) Credit Eduardo Alemeida, Ph.D., University of São Paulo Usage Restrictions Maintain attribution License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.