Ultra Conserved Elements - to conserved for Darwin

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Ultraconserved elements (UCEs) are highly conserved regions of DNA sequences that exhibit exceptional stability across evolutionary time. They are found in all eukaryotic organisms and are often located near genes that are critical for development and regulation. The high conservation of UCEs suggests that they play important roles in biological functions.

UCEs were first identified in a study of the human, rat, and mouse genomes (Bejerano et al., 2004). In this study, researchers identified 481 regions of DNA that were absolutely conserved between the three species. These regions ranged in size from 200 to 781 base pairs and were found on all chromosomes except for 21 and Y.

Subsequent studies have identified UCEs in a wide range of organisms, including vertebrates, invertebrates, and plants (Siepel et al., 2005; Derti et al., 2006; Pennacchio et al., 2006; Vavouri et al., 2007). The number of UCEs identified in different species varies, but they are typically found in the same locations and exhibit the same high degree of conservation.

The function of UCEs is still not fully understood, but there is evidence that they play important roles in biological functions. Some UCEs have been shown to be involved in gene regulation, while others have been shown to be important for chromosome structure and stability.

Here are some of the key features of UCEs:

  • High conservation: UCEs are some of the most conserved regions of DNA, exhibiting little or no variation between even distantly related species.

  • Location: UCEs are often found near genes that are critical for development and regulation.

  • Function: The function of UCEs is still not fully understood, but they are thought to play important roles in biological functions, such as gene regulation and chromosome structure.

Ultraconserved elements (UCEs) have remained virtually unchanged over billions of years. They are found in all eukaryotes, from single-celled organisms to humans, and are involved in essential cellular processes, such as transcription, translation, and DNA replication.

The existence of UCEs is a challenge to neo-Darwinism, the prevailing theory of evolution. Neo-Darwinism holds that evolution occurs through the gradual accumulation of small, random mutations in genes. However, UCEs have remained unchanged for so long that they cannot be explained by random mutations.

There are a number of possible explanations for the existence of UCEs. One is that they are so important to life that any mutation in them would be lethal. Another possibility is that UCEs are involved in regulating the expression of other genes, and that even small changes in their sequence could have a large impact on the organism's development.

Whatever the explanation, the existence of UCEs suggests that evolution is not as random as neo-Darwinists believe. It is possible that there are forces other than random mutation that are driving the evolution of life.

Here are some specific ways in which UCEs challenge neo-Darwinism:

  • UCEs are too short to have evolved through random mutations. The average UCE is only about 200 nucleotides long. Random mutations are very unlikely to produce such short sequences of DNA that are also functional.

  • UCEs are too conserved to have evolved through random mutations. UCEs have remained virtually unchanged for billions of years. This suggests that they are under strong pressure not to change, and that any mutations in them would be quickly eliminated from the population.

  • UCEs are not distributed randomly throughout the genome. UCEs are clustered together in regions of the genome that are important for gene regulation. This suggests that they are not simply the result of neutral drift, but that they have a specific function.

The existence of UCEs is a reminder that we still do not fully understand how evolution works. There are still many unanswered questions about how UCEs have evolved and what their function is. However, the existence of UCEs is a challenge to neo-Darwinism, and suggests that there may be more to evolution than we currently understand.

Ref

https://www.mdpi.com/2075-1729/13/3/637

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3862641/


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