Bones in the vertebrate cranial base and limb skeleton grow by endochondral ossification, under the control of growth plates. Mechanisms of endochondral ossification are conserved across growth plates, which increases covariation in size and shape among bones, and in turn may lead to correlated changes in skeletal traits not under direct selection. We used micro-CT and geometric morphometrics to characterize shape changes in the cranium of the Longshanks mouse, which was selectively bred for longer tibiae. We show that Longshanks skulls became longer, flatter, and narrower in a stepwise process. Moreover, we show that these morphological changes likely resulted from developmental changes in the growth plates of the Longshanks cranial base, mirroring changes observed in its tibia. Thus, indirect and non-adaptive morphological changes can occur due to developmental overlap among distant skeletal elements, with important implications for interpreting the evolutionary history of vertebrate skeletal form.
All data generated or analysed during this study are included in the manuscript and supporting Source Data files.
- Campbell Rolian
- Campbell Rolian
- Colton Michael Unger
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All animal procedures were approved by the Health Sciences Animal Care Committee at the University of Calgary (Protocols AC13-0077 and AC17-0026) and performed in accordance with best practices outlined by the Canadian Council on Animal Care.
- George H Perry, Pennsylvania State University, United States
- Received: February 18, 2021
- Accepted: April 23, 2021
- Accepted Manuscript published: April 26, 2021 (version 1)
© 2021, Unger et al.
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