EVOLUTION: Not by genetic mutations, but by Epigenetic Adaptation

microbes

This article focusses on bacterial evolutionary change, but the principle of what is discussed is fully applicable to all organisms including ourselves. For instance, a Neo-Darwinian explanation of bacterial evolution and other species across the whole spectrum of life would go something like this: Species evolve and eventually can become a different species via generations of changes in the DNA due to mutations (non-destructive and/or neutral mutations). The only problem is that species of bacteria never change into anything other than bacteria. And the idea that genetic mutations upon which natural selection acts is also be strongly criticised by a highly regarded scientist (micro-biologists, who contributed a highly significant theory about early microbial evolution to evolutionary biology), Professor Lynn Margulis, as seen in the following statement:

“Neo-Darwinists say that new species emerge when mutations occur and modify an organism. I was taught over and over again that the accumulation of random mutations led to evolutionary change [which] led to new species. I believed it until I looked for evidence” (Teresi 2011, 68)

http://discover.coverleaf.com/discovermagazine/201104?pg=68#pg683.

If it isn’t via genetic mutations, then what is driving adaptation within existing species and what is the driver of evolutionary (species) change? The answer in part, along with many other interactive processes, lays in the epigenetics. See Free e-book at ww.smashwords.com/books/view… For instance, one clincal study with bacteria (a really simple organism that should show mutations operating with selection to produce a change an adaptation) clearly, demonstrates that: “bacterial adapt to antibiotics more quickly than can be accounted for by mutations” (Janusz 2008) http://epigenome.eu/en/3,35,1110 The article is taken from the Epigenome NoE website which is a European funded project promoting excellence in science and research envolving the epigenome. The study on bacteria proposes the epigenetic explanation as it is environmentally-driven, adapting the organism’s response to stimuli (new antibiotics) by changing how the genes are expressed without changing the DNA sequence itself. We are only recently beginning to understand the epigenome as an article on Medical News Today outlines:

What is a gene? What are genes? Initially, after the Human Genome Project was completed, we thought that much of the instructions for making the proteins that make an organism was contained in a tiny part of the genome, while the rest was simply “junk” DNA, without any useful function. Later on, geneticists discovered another layer of heritable genetic data that are not held in the genome, but in the “epigenome”… In this area there are instructions on how to interpret the DNA code for the production of proteins. Some of the code for manufacturing the proteins of the epigenome was found to be hiding in junk DNA…That discovery helped us understand that the c.23,000 genes in the human genome that can be found in all the cells of the human body are expressed differently in different organs and tissues. How they are expressed depends on gene regulation instructions located in the epigenome. (Nordqvist 2013)
The complex factors working alongside epigenetic evolutionary processes involved in our emerging non-Darwinian and quantum-like evolutionary synthesis is, I believe is best summarised in the following quote by Professor James Shapiro in his blog post in the Huffington Post online: entitled: Does Natural Selection Really Explain What Makes Evolution Succeed? (2012):
In combination, cytogenetics and molecular genetics have taught us about many processes that lead to biological novelties “independently of natural selection” — hybridization, genome duplication, symbiogenesis, chromosome restructuring, horizontal DNA transfer, mobile genetic elements, epigenetic switches, and natural genetic engineering (the ability of all cells to cut, splice, copy, and modify their DNA in non-random ways). As previous blogs document and as future blogs will discuss, the genome sequence record tells us that these processes have accompanied rapid changes in all kinds of organisms. We know that many of them are activated by stress under extraordinary circumstances. (Shapiro 2012)
The last part pertaining to the activation of rather radical and rapid species adaptation by stress (environmental conditions) is fully applicable to bacteria and as a relatively simple and more primitive, but continually adapting organism, it begins to give us an insight into past evolutionary change when much more complex organisms, such as plants and animals, had not yet fulfilled their evolutionary potential and were less evolved, and not yet fully defined, they were generalists. This idea is not a new one, but one that has been around for a very long time and can be best conceptualised by applying the idea of cellular and embryonic development when the organism is highly sensitive to its internal and external environment and just like stem cells that have not yet been differentiated (can become anything in the early stages), similarly early and more primitive organisms were more susceptable to evolutionary change according to the environment they found themselves in and their genomes were also less fixed (genomically noisy). It is a complex process, but simply put: A developing embryo goes through the similar stages of development at a fundamental level to an evolving (developing) species. (E.G. see Von Baer on slide presentation/video on this site and O’Hare forthcoming – EVOLUTION: A THIRD WAY?).
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s