July 15, 2014
How Speed Restricts Evolutionary Change Of The Vertebral Column
One of the riddles of mammal evolution explained: the strong conservation of the number of trunk vertebrae. Researchers of the Naturalis Biodiversity Center and the University of Utah show that this conservation is probably due to the essential role of speed and agility in survival of fast running mammals. They measured variation in vertebrae of 774 individual mammal skeletons of both fast and slow running species. The researchers found that a combination of developmental and biomechanical problems prevents evolutionary change in the number of trunk vertebrae in fast running and agile mammals. In contrast, these problems barely affect slow and sturdy mammals. The study is published in PNAS.
In total, 774 skeletons of 90 different species were analyzed. The skeletons belonged to collections of 9 European natural history museums including Naturalis Biodiversity Center, Leiden.
"The stiffness of the back of a mammal is key to whether evolutionary change is possible or not", said Frietson Galis, one of the authors of the study. "The locomotion of slow mammals with a stiff back is only marginally affected by irregular lumbosacral joints, but for fast running mammals such joints are fatal," continued Clara ten Broek another author of the study.
"A combination of developmental, biomechanical and evolutionary insights and a large dataset were necessary to solve this puzzle of mammal evolution," said Frietson Galis.