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. 2020 Feb 6.
doi: 10.1002/jez.b.22932. Online ahead of print.

Parallel Evolution of Regressive and Constructive Craniofacial Traits Across Distinct Populations of Astyanax Mexicanus Cavefish

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Parallel Evolution of Regressive and Constructive Craniofacial Traits Across Distinct Populations of Astyanax Mexicanus Cavefish

Amanda K Powers et al. J Exp Zool B Mol Dev Evol. .

Abstract

Life in complete darkness has driven the evolution of a suite of troglobitic features in the blind Mexican cavefish Astyanax mexicanus, such as eye and pigmentation loss. While regressive evolution is a hallmark of obligate cave-dwelling organisms, constructive (or augmented) traits commonly arise as well. The cavefish cranium has undergone extensive changes compared with closely-related surface fish. These alterations are rooted in both cranial bones and surrounding sensory tissues such as enhancements in the gustatory and lateral line systems. Cavefish also harbor numerous cranial bone asymmetries: fluctuating asymmetry of individual bones and directional asymmetry in a dorsal bend of the skull. This asymmetry is mirrored by the asymmetrical patterning of mechanosensory neuromasts. We explored the relationship between facial bones and neuromasts using in vivo fluorescent colabeling and microcomputed tomography. We found an increase in neuromast density within dermal bone boundaries across three distinct populations of cavefish compared to surface-dwelling fish. We also show that eye loss disrupts early neuromast patterning, which in turn impacts the development of dermal bones. While cavefish exhibit alterations in cranial bone and neuromast patterning, each population varied in the severity. This variation may reflect observed differences in behavior across populations. For instance, a bend in the dorsal region of the skull may expose neuromasts to water flow on the opposite side of the face, enhancing sensory input and spatial mapping in the dark.

Keywords: bone fragmentation; cranial bend; dermal bone; eye loss; neuromast.

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References

REFERENCES

    1. Alvarez, J. (1946). Revisión del género Anoptichthys con descripción de una especies nueva (Pisc. Characidae). Anales de la Escuela Nacional de Ciencias Biológicas Mexico, 4, 263-282.
    1. Alvarez, J. (1947). Descripción de Anoptichthys hubbsi caracindo ciego de La Cueva de Los Sabinos. S. L. P. Revisita de la Sociedad Mexicana de Historia Natural, 8, 215-219.
    1. Atukorala, A. D. S., Hammer, C., Dufton, M., & Franz-Odendall, T. A. (2013). Adaptive evolution of the lower jaw dentition in Mexican tetra (Astyanax mexicanus). Evolutionary Development, 4, 1-11.
    1. Beale, A., Guibal, C., Tamai, T. K., Klotz, L., Cowen, S., Peyric, E., … Whitmore, D. (2013). Circadian rhythms in Mexican blind cavefish Astyanax mexicanus in the lab and in the field. Nature Communications, 4, 2769. https://doi.org/10.1038/ncomms3769
    1. Borowsky, R. (2013). Eye regression in blind Astyanax cavefish may facilitate the evolution of an adaptive behavior and its sensory receptors. BMC Biology, 11, 1-3.

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