by Michael J. Boyle, Ph.D., Brian Thomas, Ph.D., Jeffrey P. Tomkins, Ph.D., and Randy J. Guliuzza, P.E., M.D.
In Proceedings of the International Conference on Creationism. 9: 120-143, article 17.
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.
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