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

Guliuzza and Gaskill ◀ How organisms continuously track environmental changes ▶ 2018 ICC 176 Table 2 continued. Table 2 continued on next page. Mechanism Action Reference Research Entity Results Descriptive Extract of Function in CET Framework 3. Modulating Cis-regulatory Con- trol of Genes Modulation of cis-regulatory regions changes expression of gene products without changing genetic sequence. Cleves et al. 2014. Evolved tooth gain in sticklebacks is associated with a cis-regulatory al- lele of Bmp6. PNAS Threespine stickle- back Gasterosteus aculeatus Derived benthic freshwater stickleback population have about twofold gain in ventral pharyngeal tooth number and assays of Bmp6 in developing teeth show that cis- regulatory changes have ~1.4-fold up-regulation of Bmp6 relative expressio compared with their ancestral marine counterparts during late stages of stickleback development indicative of late- acting cis-regulatory up-regulation of Bmp6 expression underlies an increase in tooth number. " BMP family members have been implicated in several vertebrate evolved traits: size and shape of the beak in Darwin’s finches, size and shape of the jaw in cichlids, jaw and skull variation in brachycephalic dogs, and avian feather patterning... this apparent reuse of the same signaling pathway across taxa may reflect a predisposition for Bmp genes to be used during morphological evolution, perhaps due to having complex, modular cis- regulatory architecture to generate evolutionary variation" p. 13916. 4. Regulated Signal- ing Pathways Regulated control of amplification pathways that act in concert to mediate rapid, di- rectional ribosomal DNA copy number change. Carmen, et al. 2015. Regulation of ribosomal DNA amplification by the TOR pathway. PNAS Multiple strains of budding yeast "Here we show that signaling pathways that sense environmental nutrients control genome change at the ribosomal DNA. This demonstrates that not all genome changes occur at random and that cells possess specific mechanisms to optimize their genome in response to the environment” p. 9674. “Our results reveal how a signaling pathway can orchestrate specific genome changes and demonstrate that the copy number of repetitive DNA can be altered to suit environmental conditions...through two pathways that are coordinately regulated [to] be tailored to suit the current environment...[which] departs from the standard model of adaptation through random mutation followed by selection... [and] raises the fascinating possibility that copy number of other regions of the genome may also be controllable in response to environmental conditions” pgs. 9676- 9678. 5. Directed Homol- ogous Recombi- nation Homologous recombination is the exchange (crossing over) or replacement (gene conversion) of a DNA region by its homologous DNA sequence from the homologous chro- mosome or the sister chromatid during meiosis. Shibata, et al. 2001. Homologous genetic recombina- tion as an intrinsic dynamic property of a DNA structure induced by RecA/ Rad51-family proteins: A possi- ble advantage of DNA over RNA as genomic material. PNAS Review article. The induction of meiotic recombination depends on several genes regulated by a complex network of cellular signaling systems, as revealed by genetic studies in both yeasts. “The ability to induce homologous recombination in response to unfavorable environmental changes would be adaptive for each species, as it would increase genetic diversity and would help to avoid species’ extinction” p. 8430. Shibata. 2001. Functions of ho- mologous DNA recombination. RIKEN Review . See also: Ohta. 2001. Hierarchic regula- tion of recombina- tion, RIKEN Review Review article. “Homologous recombination is actively induced in bacteria and simple eukaryotes when cells are subjected to conditions unfavorable for their survival, such as nutritional starvation and a high cell density. While meiotic crossing over is supposed to create genetic diversity by producing new combinations of the alleles derived from parents and the genetic diversity may help cells to adapt to such unfavorable conditions…” p. 22