Genetic analysis of dermal bone fragmentation in a natural model system.

Abstract

Natural model systems that reside in extreme environments can provide powerful insights into fundamental biological processes. For instance, many of the genetic and cellular regulators of normal dermal bone formation have been clarified. However, the precise genetic and molecular bases for altered bone phenotypes evolving under environmental pressure remain largely uncharacterized. In this study, we evaluated a dermal bone fragmentation phenotype that occurs in the blind Mexican cavefish (Astyanax mexicanus). We investigated this phenotype using exhaustive cranial bone measurements in the context of an F2 pedigree of surface fish × cavefish hybrids. We determined that fragmentation of the suborbital bones occurs in a largely asymmetric fashion. Further, we clarified the genetic architecture for left‐sided and right‐sided suborbital bone fragmentation from our hybrid pedigree. Our results indicated that while the area of the face occupied by suborbital bones is constrained between different‐sized individuals, the pattern and severity of fragmentation could not easily be predicted by co‐occurrence of other degenerative characteristics. Our results may indicate a pleiotropic interaction between genes selected in the cave environment for constructive traits that interfere with normal patterns of bone ossification. Research supported by NIDCR (NIH) R03DE022403.Grant Funding Source: grossja@ucmail.uc.edu