X-ray image of a female mole rat revealing skeletal changes as she transitions into a queen
JOHNSTON ET AL., ELIFE 10, E65760 (2021)
Honey bees are social animals, with populations consisting of castes of siblings with defined divisions of labor and matching phenotypes. Drones, queens, and workers have specific jobs within the hive for reproduction, rearing the brood, or gathering pollen and nectar. The Damaraland mole rat (Fukomys damarensis) is similarly social. Groups of mole rats consist of a single breeding pair and their offspring, which divide the labor of locating food, burrowing, nest building, and caring for offspring. Knowing that, similar to honey bees, mole rats show phenotypic differences depending on caste, Johnston et al. investigated the molecular basis for these transformations. If a female mole rat is experimentally induced to become a breeding “queen,” her vertebral column lengthens. The authors found that transitions in breeding status were accompanied by skeletal gene-regulatory changes that endowed major skeletal remodeling. In addition to a lengthening of the lumbar vertebrae, gene expression analysis indicated increased bone resorption and changes in estrogen levels in queens that reduced long bone growth and femur density. These morphological costs are thus a trade-off between fertility and bone fragility.
eLife 10, e65760 (2021).