Meeting Abstract

S8-1.6  Jan. 6  Developmental evolution of BMPs: from postnatal epigenetic remodeling to adaptive genetic divergence YOUNG, Rebecca L*; BADYAEV, Alexander V; University of Arizona; University of Arizona

Evolutionary studies of ecomorphological adaptations in vertebrates have revealed a common role for bone morphogenetic proteins (BMPs) in inducing developmental changes in skeletal morphology. Whereas the importance of BMPs for adaptive evolution is widely documented, the ultimate mechanism behind the ubiquity of their involvement is not known. Here we propose two hypotheses for the origins of BMP-mediated mechanisms in ecomorphological adaptations that capitalize on the strong epigenetic regulation of BMP pathways. First, high mutability of regulatory elements of BMPs (e.g., transcription factors or promoter regions) can result in changes in spatiotemporal expression of BMP such as ectopic expression and changes in receptivity. Such modifications should lead to increases in morphological variants available to natural selection and, thus, facilitate rapid adaptation of BMP regulatory pathways and corresponding skeletal structures to novel or fluctuating environments. Alternatively, the ubiquity of BMP-mediated mechanisms in ecomorphology can be due to sensitivity of BMP pathways to external stimulation, such as muscle loading or postnatal bone remodeling. Such responsiveness might enable the development of locally adaptive plasticity in bone growth and remodeling throughout postnatal ontogeny. In turn, when a particular environment consistently induces a morph and exerts selection favoring the morph, it should favor reliable developmental incorporation of environmentally-induced pathways. We review recent empirical and experimental studies examining genetic, epigenetic, and biomechanical regulation of cartilage and bone formation, remodeling, and repair to test these alternative hypotheses.