The Institute for Creation Research (ICR) is performing controlled experiments to test the response of an organism to different environmental conditions. The animal model is Astyanax mexicanus (Mexican tetra), a freshwater fish with two well-differentiated, interfertile morphotypes: eyed surface-dwelling fish (surface fish) with a distinct pigmentation pattern, and eyeless cave-dwelling fish (cavefish) with minimal pigmentation. For this research, we have established and equipped a new biology laboratory to investigate the mechanisms and process of adaptation in this model. Preliminary results from experiments with mature adult A. mexicanus include the following: (1) Cavefish increase pigmentation across their body when exposed to high-intensity light; (2) Cavefish exhibit behavioral and physiological acclimation to high CO2 (low pH) water; (3) Surface fish decrease pigmentation across their body and labor during respiration in high CO2 (low pH) water; (4) Adult cavefish and surface fish respond to experimental treatments within weeks of treatment; and (5) Responses to treatments by both morphotypes are not limited to multigenerational genetic inheritance. The first result implies that UV light may stimulate melanosome production in adult cavefish through biochemical induction of a latent melanin synthesis pathway. Second, pre-acclimation by cavefish to acidic water chemistry likely reflects conditions within their native cave environments. Third, the comparative loss of pigmentation and associated respiratory challenges in adult surface fish exposed to darkness and high CO2 (low pH) suggest they actively self-adjust. And in contrast to cavefish, non-acclimated surface fish indicate they are outside of their native environment. The significance of this research is multifaceted. At the 8th ICC, Guliuzza and Gaskill (2018) introduced a novel paradigm: Continuous Environmental Tracking (CET). This model infers that organisms actively and continuously track conditions within specific environments to self-adjust through internal mechanisms that integrate molecular, biochemical, cellular, physiological and behavioral functionality of the whole organism. These mechanisms are predicted to operate by the same integrative principles that govern human-engineered control systems, suggesting that fish and other animals make highly-regulated responses in order to compensate for changes in external conditions that may exceed their routine efforts to maintain homeostasis. Moreover, the model also predicts that organisms can modify the course of their development; that adaptive larval and adult traits are sometimes reversible; that epigenetic modifications are heritable across multiple generations; and that common phenotypic traits will be observed among a diversity of organisms living in similar environments. Our predictions are testable. ABSTRACT I. INTRODUCTION A primary purpose of scientific experimentation is to provide data that helps researchers develop new models, and confirm, refine or reject existing theories. Theory is paramount in science since it sets research agendas, becomes the guiding interpretative framework of observations, and forms the basis for explanatory models. Our intent is to use experimental results to test whether several widespread theoretical assumptions are valid. Here, we apply new data from pigmentation experiments on multiple mating pairs of Astyanax mexicanus (Mexican tetra) to principally test theoretical assumptions of three models explaining the extreme morphological differences observed in fish living in profoundly different environments. Model one is the standard Neo-Darwinian Theory (NDT). Evolutionists prefer studying cavefish as a vertebrate model of adaptation in caves because surface-dwelling (ancestor) and cave-dwelling (descendant) forms of the same species (Fig. 1) are available for comparative research (Jeffery 2019). Model two is the historical non-evolutionary interpretation for the origin of blind cavefish. Model three is Continuous Environmental Tracking (CET), a new organism-focused, engineering-based model of adaptation (Guliuzza and Gaskill 2018). A. Conventional neo-Darwinian explanation for the origin of blind cavefish Blind Mexican cavefish (Astyanax mexicanus), “Darwin’s finches,” peppered moths, and “Lucy” are icons of Darwinian evolution. Because the loss of eyes and pigmentation following cave migration are dramatic transformations of anatomy, blind cavefish have become a notable example of Darwinian selectionism. Icons are important because they are seen as accurate illustrations of the core ideas (or basic Michael J. Boyle, Scott Arledge, Brian Thomas, Jeffrey P. Tomkins, and Randy J. Guliuzza, Institute for Creation Research, P.O. Box 59029 Dallas, Texas 75229 USA, boylem2349@gmail.com © Cedarville University International Conference on Creationism. The views expressed in this publication are those of the author(s) and do not necessarily represent those of Cedarville University. 9th 2023 Boyle, M.J., S. Arledge, B. Thomas, J.P. Tomkins, and R.J. Guliuzza. 2023. Testing the cavefish model: an organism-focused theory of biological design. In J.H. Whitmore (editor), Proceedings of the Ninth International Conference on Creationism, pp. 120-143. Cedarville, Ohio: Cedarville University International Conference on Creationism. TESTING THE CAVEFISH MODEL: AN ORGANISM-FOCUSED THEORY OF BIOLOGICAL DESIGN KEYWORDS Astyanax, cavefish, CET, pigmentation, adaptation, self-adjustment, environment, neo-Darwinian theory
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