The "honey bee reproductive ground plan" hypothesis that originated two decades ago at the University of California, Davis, with bee geneticist Robert E. Page Jr., is drawing international attention.
Page, emeritus professor of entomology at UC Davis and now founding director of the School of Life Sciences at Arizona State University, and his collaborator Gro Amdam, are featured in the Oct. 23rd edition of Science, a publication of the American Association for the Advancement of Science.
Writing in the behavior ecology section in an article headlined, "Sex and Social Structure," journalist Elizabeth Pennisi related that the scientists' research "has shown that reproductive traits help shape a honey bee worker's role in life and that ovaries are active players in the process-even if they play little role in reproduction in worker bees."
The specialized tasks "have their basis in what Amdam and Page call a reproductive ground plan," she wrote. Their work has provided a framework and tools to study division of labor, which now "converges on two genes that may explain both ovary size and behavior."
Page and Amdam, an associate professor in the School of Life Sciences and Norwegian University of Life Sciences, believe that genes and hormones likely control social roles as well as longevity.
Their research centers on the role of the ovary in honey bee colonies, and how the worker bees partition the labor of the colony with duties that include rearing young bees, constructing the nest, foraging for pollen and nectar, and processing the food.
Page, a pioneer in the field of evolutionary genetics and social behavior of bees, has long marveled at how highly social bees are. Worker bees, or infertile females, instinctively divide up their roles to run the hive, freeing the queen to lay eggs.
The worker bees serve as nurse maids, nannies, royal attendants, architects, builders, foragers, guards and undertakers.
But why are some colonies high-pollen collectors and hoarders, while others aren't?
His research on high and low pollen hoarding strains that began two decades led to the "reproductive ground plan" hypothesis. Page continues to keep his specialized bee stock, managed by bee breeder-geneticist M. Kim Fondrk, at UC Davis.
"The reproductive ground plan research is integrating developmental biology into insect sociobiology," Page told the UC Davis Department of Entomology, in response to a query. "It is completing the synthesis by looking for the signatures of levels of selection above the organism, at the level of the genes, physiology, and embryogenesis. It is substantiating the superorganism."
UC Davis is the hub for the development and maintenance of the high and low pollen hoarding strains of bees "that have been fundamental in testing the reproductive ground plan hypothesis and understanding how selection on colonies affects different levels of biological organization from genes to societies," he said.
Page began working with Amdam in 2003 when she was completing her doctoral thesis involving a yolk protein, vitellogenin, found in the blood of a bee. Wrote Pennisi: "High vitellogenin and larger ovaries lead to pollen hoarding, whereas low vitellogenin and smaller ovaries result in bees that are more interested in nectar."
Amdam moved to UC Davis in 2004 to collect bees from Page's colonies and to test them for vitellogenin. "She found that young adults from the high-pollen-hoarding strains had higher levels of vitellogenin than those from the low-pollen-hoarding stains," Pennisi noted.
Page and Amdam reported in the April 2 edition of PLoS One, that two genes may explain both ovary size and behavior. One, PDKI, deals with egg development and food-related behavior, and the other, HR46, with ovary size in workers.
Both researchers participated in the Honey Bee Genome Sequencing Consortium that published the genome of the honey bee in 2006.
Page, who received his doctorate in entomology from UC Davis, retired from UC Davis in 2004 to develop the School of Life Sciences in the College of Liberal Arts and Sciences at the Arizona State University. As its founding director, he has established the school as a platform for discovery in the biomedical, genomic and evolutionary and environmental sciences He is a highly cited author with more than 200 publications on such topics as Africanized bees, genetics and evolution of social organization, sex determination, and division of labor in insect societies.
Page has received numerous awards and honors, including election to the German Academy of Sciences Leopoldina, the American Academy of Art and Sciences, the Brazilian Academy of Science and the American Association for the Advancement of Science.
“Rob Page is a role model,” said chemical ecologist Walter Leal, professor and former chair of the Department of Entomology. “He is both a charismatic administrator and a front runner in his scientific endeavors. I am wondering how many deans made four covers in Nature, one cover in Cell and have his/her research highlighted in Science. His low and high pollen strains are remarkable resources; I am delighted we are helping him keep them in Davis."
Page and Amdam are the co-principal investigators on a federally funded project directed by UC Davis entomology professor James R. Carey. Carey directs the Biodemographic Determinants of Lifespan, a National Institutes of Health/National Institute of Aging-funded program involving scientists from UC Davis, UC Santa Barbara, UC Berkeley, Stanford and seven other academic institutions in the United States, the United Kingdom, and Greece.
The Biodemographic Determinants of Lifespan, Carey said, blends projects, aims, experiments and models. Some projects focus on the ecology and evolution of lifespan, others on the mechanisms of aging, and others on both: the function of lifespan and the mechanisms involved in aging. The scientists study aging in nematodes, honey bees, fruit flies, red deer, soay sheep and humans, and develop mathematical models targeting the evolutionary ecology of aging and lifespan.