#11 Not So Random Mutations, Oral Plugs and Evolutions Patterns from Pollution
A new discovery changing how we look at "random" mutations, how whales don't drown as a result of oral plugs as well as how evolution is influenced by pollution and the resultant knock on effects.
🧬Not So Random Mutations…
A New Discovery Transforming Our View on Evolution…
A DNA mutation is simply an alteration in the nucleotide sequence of the genome with three clear classes of DNA mutation. DNA mutations are often labelled “random” however a new discovery from the Max Planck Institute for Biology as shown how mutations of DNA do not occur quite as randomly as was previously thought. This new research may change the way we think about evolution, with insights altering crop domestication as well as cancer and medical treatments.
DNA mutations are one of the major drivers of evolution and are directly linked to Darwin’s natural selection. The general assumption of Darwin’s theory was that mutations arise randomly, and that natural selection is capable of determining which genes have change more quickly and more slowly. This assumption has now potentially been upended.
Assistant professor, Grey Monroe stated that “We always thought of mutations appearing solely by chance across the genome,”. Furthermore, the paper shows how not only is the pattern of mutations non-random, but actually non-random in a way that favours the plants.
The research team behind these statements grew specimens of the widely known Arabidopsis thaliana in a lab environment, where all the plants as well as those with harmful mutations, could reproduce. They could reproduce due to the sheltered conditions, where as in the wild selection pressures would remove these mutated plants. The samples grown were analysed with the genomes of hundreds of lab grown plants being recorded.
Scientists identified thousands of mutations as they arose in the plants. Statistical analysis revealing that these mutations were not randomly distributed through the genome. The scientists located stretches of genome where mutations were rare, with other stretches holding a lot of mutations. The regions with fewer mutations held genes that were essential to the survival and function of the cell. These were the regions of the DNA that would be sensitive to mutations with a likely fatal outcome. With scientists stating that “DNA damage repair seems therefore to be particularly effective in those regions.” This feature of the plants minimizes the risk of damage to the most vital genes.
Monroe said that the team found different types of proteins around which the DNA is wrapped in the cell nucleus and how these were highly correlated to the appearance of mutations. “It gives us a good idea of what’s going on, so that we can predict which genes are more likely to mutate than others,” Monroe said. It is important to note how unexpected these results were in light of the previously famous classical evolutionary theory.
Future applications of this discovery are limitless. Monroe said how ““The plant has evolved a way to protect its most important genes from mutation,”. Protecting vital genes is a technology that could be applied to crop production, humans as well as countless other organisms. The research team as well as others are continuing along this line of research.
🔌Newly Discovered Oral Plug
The Oral Plug Behind Whales not Drowning…
Whales are famous for feeding by gulping huge volumes of water to capture their tiny prey; krill. With the average whale being able to hold their breath for 60 minutes. Researchers are believed to have discovered an “oral plug” that can block the airways or oesophagus as needed, located in the throats of species.
Lunge feeding is a behaviour where a whale consumes a large quantity of prey and water. It is a specific strategy used by some baleen whales, such as humpbacks and blue whales and involves a high speed swim towards a big shoal of prey, scooping as much prey as possible. In doing so, they also take in a huge volumes of water, which the water “spits out” by filtering through their baleen. How this is possible has remained a mystery…
The anatomy of whales is a relatively unknown anatomy in comparison to other species with dissections rarely occurring. How the whales species are able to pull of this feeding feat without flooding either their lungs or gut was therefore unknown.
However in this new study, researchers identified a fleshy bulb that acts and functions as a “oral plug”. The plug functions by sitting behind the tongue when the animal is breathing, and so allowing air to pass into the lower airways from the nasal passage and preventing anything in the mouth “getting through”. As the whale wants to eat, the plug shifts, moving up and back, blocking the nasal passage and so creating an opening from the mouth through to the oesophagus. Simultaneously, a cartilage structure closes off the entrance to the larynx and lower airways and so preventing flooding of the lungs with either food or water.
This is the first use of this protective mechanism in Biology as we know with it not being present in any other animals. The reason for this discovery not being made previously is due to the incorrect assumption that these lunge-feeding whales had similar respiratory tracts to those of toothed whales, of which more is known, anatomically speaking. In addition the team believe that this specialised anatomy is likely key in what allows these whales to support such a large body being some of the biggest animals in the world.
More Information and Source
📊The Pattern of Evolution
Discovering the influencers and patterns of contemporary evolution…
A research team from McGill University has created a massive new dataset 80% larger than any of those before. The new dataset of close to 7,000 examples of changing traits is key in understanding numerous evolutionary processes.
Andrew Hendry, Professor of Biology at the Redpath Museum of McGill and the co-senior author on the paper said that "We have come a long way from the old view of evolution as a slow process to the point where we are now realizing that everything is evolving all around us all the time,". The research team were interested in identifying how various types of human disturbance influences changes in traits. Whilst small, a significant difference in the change of rates was seen between human disturbed populations and natural populations. Moreover, the highest rates of change were those in locations associated with intensive human disturbance.
The expanded data set analyses also confirmed that harvesting by humans led to larger rates of change than non-human disturbances. Pollution was seen to be responsible for the most rapid rate of phenotypes change in organisms across various habitats and locations. For example, tufted hair grass increased tolerance of zinc, by 80% in just 26 years. Again, it is worth noting that it is hard to determine a “natural habitat” with climate change arguably influencing every ecosystem, habitat and location on the planet.
"The critical next question is how this contemporary change matters for populations, communities, and ecosystems, as well nature's contribution to people," said first author Sarah Sanderson, PhD candidate at McGill. Another supporting example being salmon. Salmon have been getting smaller over the last century with their reduction in body size having huge positive feedback loops throughout ecosystems. Birds, bears, fish and others, now have less to eat.
Similar examples must be occurring across the globe, with further research and action key to negate and mitigate the issue as much as possible.
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Click on the text below to keep reading…
🧬Not So Random Mutations…
SciTechDaily By MAX-PLANCK-GESELLSCHAFT (2022) https://scitechdaily.com/dna-mutations-do-not-occur-randomly-discovery-transforms-our-view-of-evolution/
Reference: “Mutation bias reflects natural selection in Arabidopsis thaliana” by J. Grey Monroe, Thanvi Srikant, Pablo Carbonell-Bejerano, Claude Becker, Mariele Lensink, Moises Exposito-Alonso, Marie Klein, Julia Hildebrandt, Manuela Neumann, Daniel Kliebenstein, Mao-Lun Weng, Eric Imbert, Jon Ågren, Matthew T. Rutter, Charles B. Fenster and Detlef Weigel, 12 January 2022, Nature. DOI: 10.1038/s41586-021-04269-6
🔌Newly Discovered Oral Plug
Michael Irving, New Atlas. (2022) https://newatlas.com/biology/oral-plug-whales-choke/
Gil, K. N., Vogl, A. W. & Shadwick, R. E. Anatomical mechanism for protecting the airway in the largest animals on Earth. Current Biology (2022). doi:10.1016/j.cub.2021.12.040
📊The Pattern of Evolution
McGill University. "Uncovering the underlying patterns in contemporary evolution: Evolutionary impacts of pollution and human harvesting highlighted by new global dataset." ScienceDaily. ScienceDaily, 19 January 2022. <www.sciencedaily.com/releases/2022/01/220119135037.htm>.
Sarah Sanderson, Marc‐Olivier Beausoleil, Rose E. O’Dea, Zachary T. Wood, Cristian Correa, Victor Frankel, Lucas D. Gorné, Grant E. Haines, Michael T. Kinnison, Krista B. Oke, Fanie Pelletier, Felipe Pérez‐Jvostov, Winer D. Reyes‐Corral, Yanny Ritchot, Freedom Sorbara, Kiyoko M. Gotanda, Andrew P. Hendry. The pace of modern life, revisited. Molecular Ecology, 2021; DOI: 10.1111/mec.16299