Abridgment of thesis--New York University. / Bibliography: p. 96-100.

Thesis--New York University. / Bibliography: p. 109-112.

Adaptation to any environment through the course of its evolution involves the alteration of multiple traits to ensure survival, Astyanax mexicanus is a notable example of this. Some of the most notable differences between the surface and cave populations are loss of pigmentation, decreased sleep, and reduced eyes. 208 surface – cave F2 hybrids were assessed for several morphological and behavioral phenotypes. There were significant differences found between pigmented and albino individuals, raising the question of a shared genetic basis for these traits. Oculocutaneous albinism 2 (oca2) is a notable contributor to albinism in many species, including A. mexicanus. Surface fish with CRISPR mutations at oca2 confirmed a contribution of oca2 in sleep loss within albino cavefish. Further, it was determined that oca2 is under selection and possibly has a pleiotropic function, which underlies the adaptive evolution of sleep loss and albinism. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Brain atlases have been created across species from flies to humans in order to obtain a better understanding of neuroanatomical morphology. Although these brain atlases allow for analysis of neuroanatomy they do not give insight about how the morphology adapt to fit challenges brought on by unique environments. Here I developed a brain atlas for Astyanax mexicanus, a species known to have populations that differ in various behaviors, to gain a better understanding about how populations of the same species, derived from different environments, evolve to be best suited for the challenges they face. By creating a brain atlas for adult surface fish and three populations of cavefish I was able to examine differences in neuroanatomical structures implicated in regulating behavior. My findings show significant differences in neuroanatomical regions known to regulate behavior. Along with these findings, the brain atlases created are a tool for researches to use and expand on in the future. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

In recent years, considerable progress has been made towards understanding the genetic basis of the evolution of morphological traits. In contrast, relatively little is known about how behavioral traits evolve. Astyanax mexicanus, a species of fish that exists in both surface and cave forms, is an ideal system to study behavioral evolution. Surface and cave morphs of Astyanax mexicanus differ in a variety of morphological and behavioral traits. They are interfertile, allowing for genetic analysis of the evolution of these traits. Finally, Astyanax mexicanus exists in multiple, independently evolved cave populations, providing an excellent system for studying convergent evolution.

This thesis deals with the detection of magnetic field perception of cavefishes the Mexican tetra (Astyanax mexicanus). The experiments were carried out in a plus-shaped maze where the direction preference in the individual arms of this maze was studied both in the natural Earth´s magnetic field and in the modified one by using magnets and turning the north-south axis by 90°. The reactions of the specimen on placing a strong magnet close behind the end of the western and later also the eastern arm of the plus-shaped maze were also monitored. It was conclusively found that the Mexican tetra prefer north-south axis. However, after turning the magnetic field by 90° there was no preference of the specimen for the new north-south axis as we expected. Although some of the tests performed here show the perceptiveness of magnetic field of the Mexican tetra and their preference for the noth-south axis, other tests disprove the formulated hypothesis. That is why other new hypotheses about the perceptiveness of the magnetic field should be created so that they could not be disproved in either case. This thesis has served as a stepping stone for further research in the field of magnetoreception of cavefishes.

Sleep is a complex behavioral state with ramifications on multiple levels of homeostasis including bodily function, neural activity, and molecular signaling. Sleep is conserved across evolution, though significant variations in sleep duration, architecture, and behavior are found across phyla. Decoding neural processing underlying behavior, including sleep, is a fundamental aim in neuroscience, and understanding how such behavior has evolved remains largely unknown. The encompassing goal of this dissertation is to elucidate the genetic and neuronal factors at play in the evolution of sleep loss in the blind Mexican tetra, Astyanax mexicanus. To this end, the work found within will explore peripheral sensory systems regulating distinct mechanisms of sleep loss, demonstrate how evolved changes in specific hypothalamic circuits drive sleep reductions, apply computational techniques to understand whole-brain evolution, and finally, will show how the generation of transgenic tools in a novel model system can be harnessed to assist functional experimental paradigms in relation to evolution and behavior. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

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