Constraints on the evolvability of the vertebral column in mammals
Friday seminar by Frietson Galis from Naturalis Biodiversity Center, The Netherlands
The spectacular diversification of the vertebrate body plan since the Ordovician is to an important extent due to the evolvability of the segmented vertebral column. Alongside the remarkable evolutionary diversification, there has also been impressive conservation of the vertebral column. The number of vertebrae within specific vertebral regions is for instance highly conserved in many vertebrate taxa.
Earlier, we have shown that changes of cervical numbers occur commonly in humans and other mammals, but are extremely strongly selected against due to the unavoidable coupling with pleiotropic effects. In this talk I present new data on humans and on other extant and extinct species and discuss this in the light of our earlier findings on cervical vertebare. Another example of conservation is the number of trunk vertebrae in mammals. This number is highly conserved in many taxa, but not in others. We propose that next to developmental constraints, biomechanical constraints are of primary importance in the conservation of this number. More specifically, we propose that in fast-running mammals changes of the number of presacral vertebrae are much stronger selected against than in slower-running mammals. We present data in support of our hypotheses and we discuss these data in the light of the role of natural selection in the conservation of body plans.
Naturalis Biodiversity Center
2333 CR Leiden