Related Experiment Video
Updated: Jul 13, 2026

Culture of Murine Embryonic Metatarsals: A Physiological Model of Endochondral Ossification
Published on: December 3, 2016
Gene duplication and the evolution of vertebrate skeletal mineralization
Kazuhiko Kawasaki1, Anne V Buchanan, Kenneth M Weiss
1Department of Anthropology, Pennsylvania State University, University Park, PA 16802, USA. kuk2@psu.edu
Abstract:
The mineralized skeleton is a critical innovation that evolved early in vertebrate history. The tissues found in dermal skeletons of ancient vertebrates are similar to the dental tissues of modern vertebrates; both consist of a highly mineralized surface hard tissue, enamel or enameloid, more resilient body dentin, and basal bone. Many proteins regulating mineralization of these tissues are evolutionarily related and form the secretory calcium-binding phosphoprotein (SCPP) family. We hypothesize here the duplication histories of SCPP genes and their common ancestors, SPARC and SPARCL1. At around the same time that Paleozoic jawless vertebrates first evolved mineralized skeleton, SPARCL1 arose from SPARC by whole genome duplication. Then both before and after the split of ray-finned fish and lobe-finned fish, tandem gene duplication created two types of SCPP genes, each residing on the opposite side of SPARCL1. One type was subsequently used in surface tissue and the other in body tissue. In tetrapods, these two types of SCPP genes were separated by intrachromosomal rearrangement. While new SCPP genes arose by duplication, some old genes were eliminated from the genome. As a consequence, phenogenetic drift occurred: while mineralized skeleton is maintained by natural selection, the underlying genetic basis has changed.
Related Concept Videos
Gene Duplication and Divergence
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
Bone Formation by Endochondral Ossification
The Bone Matrix
Bone Formation by Intramembranous Ossification
The process begins when mesenchymal cells in the embryonic skeleton gather together and differentiate into osteogenic cells, which then develop into...
Gene Families
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Skeleton and Calcium Homeostasis

