Epigenetics explains Darwins Finches better than NeoDarwinism


The article "Epigenetics and the Evolution of Darwin's Finches" by Skinner et al. explores the role of epigenetics in the evolution of Darwin's finches. Darwin's finches are a group of closely related birds that live on the Galapagos Islands. Over time they have diversified into 15 different species, each with a unique beak shape that is adapted to a specific diet.

The prevailing theory of evolution states that genetic mutations (NeoDarwinism) are the primary source of heritable phenotypic variation. However, epigenetic changes can also cause heritable changes in gene expression, without altering the DNA sequence. Epigenetic changes can be caused by environmental factors, such as diet, stress, and exposure to toxins. They can also be inherited from parents to offspring.

Skinner et al. compared the epigenetic profiles of several species of Darwin's finches. They found that the finches with the most specialized beaks had the most epigenetic changes. For example, the finches with the longest beaks had a higher level of DNA methylation in genes that control beak growth.

The authors suggest that epigenetic changes may have played a role in the evolution of Darwin's finches. They argue that epigenetic changes could have allowed the finches to rapidly adapt to new food sources and habitats. For example a small change in beak shape could have been amplified by epigenetic changes, leading to the evolution of a new species with a more specialized beak.

The study by Skinner et al. provides new insights into the role of epigenetics in evolution. It suggests that epigenetic changes can be a powerful force for evolutionary change, especially in rapidly adapting populations. The findings of this study could have important implications for our understanding of the evolution of other organisms, including humans.

Here are some additional thoughts on the article:

  • The study by Skinner et al. is a valuable contribution to the field of evolutionary biology. It provides strong evidence that epigenetic changes can play a role in the evolution of complex traits, such as beak shape in Darwin's finches.

  • The study raises some interesting questions about the relationship between epigenetics and natural selection. It is possible that epigenetic changes can be favored outside of natural selection, if they confer a fitness advantage to the organism without mutations. However, it is also possible that epigenetic changes can be neutral or even harmful, and that they are simply passed on from parents to offspring.

  • More research is needed to fully understand the role of epigenetics in evolution. However, the study by Skinner et al. provides a promising starting point for future research.

Article snippets:

The prevailing theory for the molecular basis of evolution involves genetic mutations that ultimately generate the heritable phenotypic variation on which natural selection acts.

However, epigenetic transgenerational inheritance of phenotypic variation may also play an important role in evolutionary change.

This study was designed to compare epigenetic changes among several closely related species of Darwin’s finches, a well-known example of adaptive radiation.

Genetic mutations using copy number variation (CNV) were compared with epigenetic alterations associated with differential DNA methylation regions (epimutations).

Epimutations were more common than genetic CNV mutations among the five species; furthermore, the number of epimutations increased monotonically with phylogenetic distance.

Interestingly, the number of genetic CNV mutations did not consistently increase with phylogenetic distance.

Specific epimutations were associated with genes related to the bone morphogenic protein, toll receptor, and melanogenesis signaling pathways.

Species-specific epimutations were significantly overrepresented in these pathways.

it is possible that epigenetic changes contribute to the molecular basis of the evolution of Darwin’s finches.

In order for inherited epigenetic changes to play a significant role in microevolution, they must persist for tens of generations, or longer.

It is conceivable that epigenetic changes may also accumulate over longer periods of evolutionary time, contributing to processes such as adaptive radiation.

This hypothesis assumes that epigenetic changes persist over thousands of generations.

Only selection on phenotypic traits with a heritable basis can lead to evolutionary change with NeoDarwinism.

As epigenetic changes are also influenced by environmental factors, and can be heritable across generations (Skinner et al. 2010), they provide another molecular mechanism that can influence evolutionary change.

Although Lamarck (1802) proposed that environmental factors can influence inheritance directly, his mechanism has not been widely recognized as a component of modern evolutionary theory.

Epigenetic changes can, in fact, increase the heritable phenotypic variation.

Epigenetics appears to provide a molecular mechanism that can increase phenotypic variation.

Studies such as these suggest that environmental epigenetics may play a role in evolutionary changes through processes, such as sexual selection.

Recent reviews suggest a pervasive role for epigenetics in evolution.

This study provides one of the first genome-wide comparisons of genetic and epigenetic mutations among related species of organisms.

There were relatively more epimutations than genetic CNV mutations among the five species of Darwin’s finches, which suggests that epimutations are a major component of genome variation during evolutionary change.

In contrast, there was no significant relationship between the number of genetic CNV changes and phylogenetic distance (NeoDarwinism).

Among the five species of finches there were fewer genetic mutations (CNV) than epigenetic mutations.

The number of epimutations increased monotonically with phylogenetic distance.

Genetic mutations are postulated to provide much of the variation upon which natural selection acts.

However, genetic changes alone are limited in their ability to explain phenomena ranging from the molecular basis of disease etiology to aspects of evolution.

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