Collaborative Research: IntBIO: Mammalian Tail Innovations & Variety Revealed By the Intersection of Genetics, Biomechanics, and Macroevolution

About This Grant

Mammals evolved from a reptile-like ancestor that used its limbs and tail together for walking and running. In early mammals, however, the limbs moved independently from the tail. This allowed mammal tails to evolve entirely new functions or to disappear in species like humans and other apes. Mammal tails play essential roles in movement, social interaction, energy storage, and protection. These many functions are enabled by variation in the shape, size, and number of individual vertebrae. Yet, little is known about how such variety arose during mammal evolution, how different tails develop from embryo to adult, or how different bone-tendon-muscle connections determine how a tail is used. This interdisciplinary research program will answer these questions and provide training for students and postdoctoral fellows across three laboratories. The research will also inspire an interactive exhibit in collaboration with the University of Michigan Natural History Museum. This exhibit will include 3-D printed mammal tails, representing both real and imaginary forms, strung with cables that will allow visitors to explore how tails function. In doing so, visitors will gain an intuitive understanding of how changes in tail anatomy favor specific uses. This collaborative proposal leverages over ten years of synergy among the research team members, combining insights from phylogenetic comparative models, evolutionary developmental biology, and biomechanics. In Aim 1, a broad survey of tail morphology in extant and extinct mammals will determine how the modularity of tail shape evolved. The evolution of tail morphology across mammals will be modeled to test whether speciation rates and ecological adaptation influenced tail variations. These insights will pinpoint specific evolutionary and ecological factors that shaped tail differences. In Aim 2, studies address a gap in our understanding of the genetic mechanisms that drive this variation. Laboratory mice and bipedal jerboas will be used to elucidate the genetic controls of vertebral elongation, which will shed light on the broader evolutionary influences on tail morphology across mammals. Finally, in Aim 3, robotic models will be used to understand how inter- and intraspecific variation in vertebral proportion affect tail function. This approach seeks to understand the functional implications of varying tail designs, linking physical attributes directly to their ecological, evolutionary, and genetic origins. The work has potential for the development of new biotechnology particularly in the field of robotics. This project was co-funded by the Physiological Mechanisms and Biomechanics Program and the Developmental Systems Cluster in the Division of Integrative Organismal Systems, the Systematics and Biodiversity Science Cluster in the Division of Environmental Biology, and by the Division of Emerging Frontiers, all in the Directorate for Biological Sciences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.