Epigenetics and the evolution of form outside of NeoDarwinism

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The article "Epigenetics and the evolution of form: Experimental manipulation of a chromatin modification causes species-specific changes to the craniofacial skeleton", by DeLorenzo et al. (2019) provides evidence that epigenetic changes can play a role in the evolution of form. The authors studied the effects of manipulating a specific chromatin modification, H3K27me3, on the craniofacial skeleton of cichlids. H3K27me3 is a histone modification that is associated with epigenetic gene silencing.

The authors found that reducing H3K27me3 levels at specific genes in the craniofacial region of cichlid resulted in changes to the shape of the skull and jaw. These changes were similar to those seen in some species of bats, which have evolved to have elongated snouts and jaws.

The authors also found that the epigenetic changes they induced were heritable, meaning that they were passed on to the offspring of the cichlid. This suggests that epigenetic changes can contribute to the development of new forms. This study is significant because it provides direct evidence that epigenetic changes can cause changes to the skull and jaw, which are important components of the craniofacial skeleton. The study also shows that these epigenetic changes can be heritable, which suggests that they could play a role in the evolution of new forms.

Other studies have also shown that epigenetic changes can influence the evolution of form. For example, a study of Darwin's finches found that epigenetic changes in the beak gene Hoxc8 were associated with differences in beak shape between different species of finches.

Overall, the evidence suggests that epigenetic changes can play a role in the evolution of form by providing a source of variation. However, more research is needed to understand the specific mechanisms by which epigenetic changes influence the development of morphological traits.

The study by Leah DeLorenzo and colleagues challenges neo-Darwinism in the following ways:

  • Neo-Darwinism traditionally focuses on DNA mutations as the primary driver of evolutionary change. However, epigenetics provides a mechanism by which environmental factors can influence gene expression without altering the DNA sequence itself. DeLorenzo's study shows that epigenetic changes can cause species-specific changes to the craniofacial skeleton, even in the absence of DNA mutations.

  • Neo-Darwinism also emphasizes the gradual accumulation of small changes over time. However, DeLorenzo's study shows that epigenetic changes can lead to relatively large phenotypic changes in a single generation. This suggests that evolution can occur more rapidly than previously thought.

  • Neo-Darwinism has difficulty explaining how acquired characteristics can be inherited. Epigenetics provides a potential mechanism for the inheritance of acquired characteristics. For example, if an organism experiences a stressful environment, this can lead to epigenetic changes that can then be passed on to its offspring.

Overall, DeLorenzo's study suggests that epigenetics plays a more important role in evolution than previously thought. This challenges some of the core assumptions of neo-Darwinism, and suggests that we need to rethink our understanding of how evolution works.

It is important to note that DeLorenzo's study is just one example of how epigenetics is challenging neo-Darwinism. Many other studies have shown that epigenetic changes can influence a wide range of traits, including morphology, behavior, and disease. This growing body of evidence suggests that epigenetics is a major player in evolution, and that we need to update our evolutionary models to reflect this.

Here is a specific example of how DeLorenzo's study challenges neo-Darwinism:

  • Neo-Darwinism predicts that the evolution of the craniofacial skeleton would require the gradual accumulation of DNA mutations. However, DeLorenzo's study showed that a single epigenetic change can cause a significant change to the craniofacial skeleton in a single generation. This suggests that evolution can occur more rapidly than neo-Darwinism predicts.

Another challenge that epigenetics poses to neo-Darwinism is the question of how acquired characteristics can be inherited. Neo-Darwinism has difficulty explaining this because it focuses on DNA mutations, which are not directly influenced by the environment. However, epigenetics provides a potential mechanism for the inheritance of acquired characteristics. For example, if an organism experiences a stressful environment, this can lead to epigenetic changes that can then be passed on to its offspring. This suggests that epigenetics may play a role in the transmission of environmental effects across generations.

Overall, DeLorenzo's study is a significant contribution to our understanding of epigenetics and its role in evolution. It challenges some of the core assumptions of neo-Darwinism and suggests that we need to rethink our understanding of how evolution works.

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