The Evolution of the Cavefish Craniofacial Complex

Gross, Joshua B.; Powers, Amanda K.

doi:10.1016/b978-0-12-802148-4.00010-4

Cited by 13 publications

(20 citation statements)

References 34 publications

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“…Therefore, we reasoned that superficial neuromast pattern and positioning would demonstrate higher measures of symmetry in surface versus cave-dwelling populations. This follows the observation that surface fish demonstrate near perfect cranial symmetry with respect to the facial bones that encircle the eye (the “circumorbital” series) [4]. In contrast, cave-dwelling populations harbor substantial asymmetry across the left-right axis for this bony complex at both the individual and population levels [4,7].…”

Section: Introductionmentioning

confidence: 58%

“…Surface-dwelling fish demonstrate higher morphological symmetry in their cranial complex compared to cavefish populations [4]. For instance, while cavefish are asymmetric with respect to numerous features of their circumorbital bone series, surface fish have not been shown to demonstrate abnormalities [4].…”

Section: Resultsmentioning

confidence: 99%

“…For instance, while cavefish are asymmetric with respect to numerous features of their circumorbital bone series, surface fish have not been shown to demonstrate abnormalities [4]. These include a variety of fusions of the six dermal bones comprising the circumorbital series, as well as substantial “fragmentation” of the third suborbital bone.…”

Section: Resultsmentioning

confidence: 99%

“…However, subsequent discoveries of additional cavefish populations across the Sierra de El Abra landscape of northeastern Mexico demonstrated that fragmentation arises as a normative component of cavefish cranial bone development [2,3]. These fragmentation phenotypes have evolved in different cave populations (Figure 1), reviewed in [4]. …”

Section: Introductionmentioning

confidence: 99%

“…These mechanoreceptive structures are made up of sensory hair cells and are crucial signaling centers conferring a keen sense of water movements (e.g., hydrodynamic flow, vibration) and facilitating foraging in the total darkness of the cave [6]. Notably, surface-dwelling fish from the rivers and streams surrounding the El Abra cave complex never demonstrate the fragmentation phenotype [4]. Moreover, the density of cranial neuromasts overlying the SO3 bone in surface fish is modest in comparison to cavefish.…”

Section: Introductionmentioning

confidence: 99%

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Asymmetric Facial Bone Fragmentation Mirrors Asymmetric Distribution of Cranial Neuromasts in Blind Mexican Cavefish

2016

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Craniofacial asymmetry is a convergent trait widely distributed across animals that colonize the extreme cave environment. Although craniofacial asymmetry can be discerned easily, other complex phenotypes (such as sensory organ position and numerical variation) are challenging to score and compare. Certain bones of the craniofacial complex demonstrate substantial asymmetry, and co-localize to regions harboring dramatically expanded numbers of mechanosensory neuromasts. To determine if a relationship exists between this expansion and bone fragmentation in cavefish, we developed a quantitative measure of positional symmetry across the left-right axis. We found that three different cave-dwelling populations were significantly more asymmetric compared to surface-dwelling fish. Moreover, cave populations did not differ in the degree of neuromast asymmetry. This work establishes a method for quantifying symmetry of a complex phenotype, and demonstrates that facial bone fragmentation mirrors the asymmetric distribution of neuromasts in different cavefish populations. Further developmental studies will provide a clearer picture of the developmental and cellular changes that accompany this extreme phenotype, and help illuminate the genetic basis for facial asymmetry in vertebrates.

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Section: Introductionmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Asymmetric Facial Bone Fragmentation Mirrors Asymmetric Distribution of Cranial Neuromasts in Blind Mexican Cavefish

2016

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

Gross

Powers

2018

The Anatomical Record

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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.

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Canal neuromast position prefigures developmental patterning of the suborbital bone series in Astyanax cave- and surface-dwelling fish

Powers

Boggs

Gross

2018

Developmental Biology

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Developmental patterning is a complex biological phenomenon, involving integrated cellular and molecular signaling across diverse tissues. In Astyanax cavefish, the lateral line sensory system is dramatically expanded in a region of the cranium marked by significant bone abnormalities. This system provides the opportunity to understand how facial bone patterning can become altered through sensory system changes. Here we investigate a classic postulation that mechanosensory receptor neuromasts seed intramembranous facial bones in aquatic vertebrates. Using an in vivo staining procedure across individual life history, we observed infraorbital canal neuromasts serving as sites of ossification for suborbital bones. The manner in which cavefish departed from the stereotypical and symmetrical canal neuromast patterns of closely-related surface-dwelling fish were associated with specific changes to the suborbital bone complex. For instance, bony fusion, rarely observed in surface fish, was associated with shorter distances between canal neuromasts in cavefish, suggesting that closer canal neuromasts result in bony fusions. Additionally, cavefish lacking the sixth suborbital bone (SO6) uniformly lacked the associated (sixth) canal neuromast. This study suggests that patterning of canal neuromasts may impact spatial position of suborbital bones across development. The absence of an eye and subsequent orbital collapse in cavefish appears to influence positional information normally inherent to the infraorbital canal. These alterations result in coordinated changes to adult neuromast and bone structures. This work highlights complex interactions between visual, sensory and bony tissues during development that explain certain abnormal craniofacial features in cavefish.

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The Evolution of the Cavefish Craniofacial Complex

Cited by 13 publications

References 34 publications

Asymmetric Facial Bone Fragmentation Mirrors Asymmetric Distribution of Cranial Neuromasts in Blind Mexican Cavefish

Asymmetric Facial Bone Fragmentation Mirrors Asymmetric Distribution of Cranial Neuromasts in Blind Mexican Cavefish

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

Canal neuromast position prefigures developmental patterning of the suborbital bone series in Astyanax cave- and surface-dwelling fish

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