A Natural Animal Model System of Craniofacial Anomalies: The Blind Mexican Cavefish.

Natural model systems evolving under extreme environmental pressures provide the opportunity to advance our knowledge of how the craniofacial complex evolves in nature. Unlike traditional models, natural systems are less inbred, and, therefore, better model the complex variation of the human population. Owing to the nature of certain craniofacial aberrations in blind Mexican cavefish, we suggest that this organism can provide new insights to a variety of craniofacial changes. Diverse cranial features have evolved in natural cave-dwelling Astyanax fish, which have thrived in the unforgiving darkness and nutrient-poor environment of the cave for countless generations. While the genetic and environmental underpinnings of various cranial anomalies have been investigated for decades, a comprehensive characterization of their molecular and developmental origins remains incomplete. Cavefish provide numerous advantages given the availability of genomic resources, developmental and molecular tools, and the presence of a normative surface-dwelling "ancestral" surrogate for comparative studies. By leveraging the frequency of abnormal and asymmetric cranial features in cavefish, we anticipate advances in our knowledge of the etiologies of irregular cranial features. Extreme adaptations in cavefish are expected to offer new insights into the complex and multifactorial nature of craniofacial disorders and facial asymmetry. Anat Rec, 2018.