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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Neuroanat. | doi: 10.3389/fnana.2019.00088

An adult brain atlas reveals broad neuroanatomical changes in independently evolved populations of Mexican cavefish

  • 1Jupiter Life Science Initiative, Department of Biological Science, Charles E. Schmidt College of Science, Florida Atlantic University, United States
  • 2Florida Atlantic University, United States
  • 3Stowers Institute for Medical Research, United States
  • 4Harriet L. Wilkes Honors College, Florida Atlantic University, United States
  • 5University of Minnesota Twin Cities, United States
  • 6University of Kansas Medical Center, United States

A shift in environmental conditions impacts the evolution of complex developmental and behavioral traits. The Mexican cavefish, Astyanax mexicanus, is a powerful model for examining the evolution of development, physiology, and behavior because multiple cavefish populations can be compared to an extant, ancestral-like surface population of the same species. Many behaviors have diverged in cave populations of A. mexicanus, and previous studies have shown that cavefish have a loss of sleep, reduced stress, an absence of social behaviors, and hyperphagia. Despite these findings, surprisingly little is known about the changes in neuroanatomy that underlie these behavioral phenotypes. Here, we use serial sectioning generate brain atlases of surface fish and three independent cavefish populations. Volumetric reconstruction of serial-sectioned brains confirms convergent evolution on reduced optic tectum volume in all cavefish populations tested. In addition, we quantified volumes of specific neuroanatomical loci within several brain regions that have previously been implicated in behavioral regulation, including the hypothalamus, thalamus, and habenula. These analyses reveal an enlargement of the hypothalamus in all cavefish populations relative to surface fish, as well as subnuclei-specific differences within the thalamus and prethalamus. Taken together, these analyses support the notion that changes in environmental conditions are accompanied by neuroanatomical changes in brain structures associated with behavior. This atlas provides a resource for comparative neuroanatomy of additional brain regions and the opportunity to associate brain anatomy with evolved changes in behavior.

Keywords: A. mexicanus, Hypothalamus, brain evolution, Brain Atlas, Sleep, stress, feeding

Received: 29 May 2019; Accepted: 11 Sep 2019.

Copyright: © 2019 Loomis, Peuss, Jaggard, Wang, McKinney, Raftopoulos, Raftopoulos, Whu, Green, McGaugh, Rohner, Keene and Duboue. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Mx. Erik R. Duboue, Jupiter Life Science Initiative, Department of Biological Science, Charles E. Schmidt College of Science, Florida Atlantic University, Jupiter, United States, eduboue@fau.edu