The Proceedings of the Eighth International Conference on Creationism (2018)

Wrasse, they document a thoroughly internal mechanism mediated by the hypothalamo-pituitary-gonadal axis in a female detecting an absent male, and subsequent sexual transformation. B. Epigenetic response Some theorists speculate that hydrogen sulfide (H 2 S) is essential to a natural origin of life, shapes evolutionary diversification, and contributes to mass extinctions (Olson and Straub 2015). H 2 S is largely an environmental toxin introduced via natural geochemical and biological processes, or industrialization. Kelley et al. (2016) looked at the target condition of H 2 S in three river drainage systems in Mexico. They found that when exposed to varying H 2 S concentrations, genetic transcription within gill tissue of small live-bearing fish of the Poecilia mexicana species complex demonstrated, on average, 1,626 up-regulated and 1,827 down- regulated transcripts adaptively correlated to mediating H 2 S flux into the fish through diffusion, regulating H 2 S homeostasis, and mitigating side effects by detoxification. To investigate one mechanism which might link ambient temperature changes to adaption, Weyrich et al. (2016) obtained five genetically heterogenous male wild guinea pigs ( Cavia aperea ) originating from Argentina and Uruguay. The environmental target condition was ambient heat. Researchers proceeded on the assumption that guinea pigs have a neurological mechanism to detect temperature changes (without identifying a specific sensor.) Males sired an F1 generation. Prior to the next mating, males were kept in cages placed on a heating plate which kept the floor at 30 °C for one cycle of spermatogenesis (60 days). F1 and F2 generations were obtained after mating with the same females. Comparison of epigenetic methylation of specific genomic regions in liver and testis between pre-and-post heat treatment found epigenetic changes in both paternal guinea pigs and F2 offspring on 13 of 19 temperature-regulating genes, and 12 additional genes involved in temperature regulation had their promoters epigenetically altered. If an adult mouse learned to fear the scent of fox urine, such information could be useful to offspring. Dias and Ressler (2014) conditioned male lab mice ( Mus muluscus ) to fear a target condition: acetophenone (cherry blossom) odor. With each exposure, males received painful foot shocks. The sensor was an olfactory bulb developmentally controlled by the M71 gene related to acetophenone. Offspring of males mated to naïve females had an increased number of odor-specific cells, increased size of odor- specific glomerulus in their nose, and 200% increase in response to acetophenone compared to controls. Phenotypic changes were mediated by epigenetic methylation of an unaltered M71 sequence. Offspring conceived by artificial insemination from sperm of acetophenone-fearing fathers had similar changes. The molecular basis of the adaptive changes in Darwin’s finches on the Galapagos islands is assumed to be genetic variation fractioned out through differential survival. However, McNew et al. (2017) note that “growing evidence suggests that epigenetic mechanisms, such as DNA methylation, may also be involved in rapid adaptation to new environments” (p.1). Comparing over 1,000 birds in adjacent “rural” and “urban” populations of each of two species of ground finches ( Geospiza fortis and G. fuliginosa ) on Santa Cruz Island, they found significant morphological differences in beak depth, width, length, chord length, and tarsus length between urban and rural populations of G. fortis (but not for body mass), and no statistical changes for G. fuliginosa . Copy number variations between populations of either species were mostly unchanged. Phenotypic differences were associated with the dramatic DNA methylation variances discovered between urban and rural populations. They speculate that a change toward human- associated foodstuffs is the target environmental condition. Urban finches face far greater exposure. They reported no identifiable link between the exposure and epigenetic changes, which were explained as “environmentally-induced epimutations.” C. Distributive response Drosophilids have innate and species-specific humidity preferences. Enjin et al. (2016) were the first to describe genes and neurons necessary for hygrosensation in the vinegar fly. The target environmental condition is relative humidity, which is used as a cue to navigate to different environments. D. melanogaster has sensors for dry, moist, and cold conditions through neuron tips in a specialized organ in the antenna. They identified the detector enabling D. melanogaster to track humidity changes and migrate accordingly. Gulls of the family Laridae are found in both freshwater and saltwater environments. Barrnett et al. (1983) describe the de-novo membrane biogenesis of an “avian salt gland.” The gland’s osmotic action extracts excess sodium from plasma and excretes it through a port in the nasal beak. The target environmental condition is brackish water. Gulls possess an osmotic sensor in the cardiac vasculature. After detecting increased sodium ion concentration, neurologic and endocrine actions control cell differentiation and hypertrophy to form the gland. The organ formation is reversible, enabling gulls to migrate between freshwater and brackish estuaries. 3. Reversibility of Adaptation If a population steadily expresses traits highly specialized for one niche, then it could head down a genetically unrecoverable one- way street. Mundy et al. (2016) observed that this circumstance could “lead to a genetic constraint on adaptation if the environment subsequently changes” (p. 1) which forces them into occupying a certain niche or dying. Their concern, within the current framework, is that “in evolutionary biology, Dollo’s Law [of irreversibility] proposes that complex adaptations cannot be reacquired easily once lost” due to degeneration of developmental pathways as mutations accumulate. Other theorists question the validity of the “irreversibility” concept. Reversals have been documented in the reappearance of teeth in certain frogs (Wiens 2011) and in the lineage of an extinct kangaroo (Couzens et al. 2016), and in beak morphology in a lineage of Hawaiian birds (Freed et al. 2016). These researchers also document, by way of historical background, the reacquisition of certain traits, including: reversals for wings in stick insects, coiling in snail shells, color vision, eggshells in boid snakes, and others. Two microbiologists (Ogbunuga and Hartl 2016) working to treat drug-resistant malaria through various paths of “reverse evolution” stated, “the lack of a coherent understanding of reverse evolution is partly due to conceptual ambiguity: the term ‘reverse Guliuzza and Gaskill ◀ How organisms continuously track environmental changes ▶ 2018 ICC 164