Speciation is not evolution - Epigenetic mechanisms behind organismal change

Speciation can occur rapidly and there's no need for a single change in DNA

https://news.mit.edu/2012/rna-splicing-species-difference-1220

Excerpts:"When genes were first discovered, the canonical view was that each gene encodes a unique protein. However, biologists later found that segments of genes can be combined in different ways, giving rise to many different proteins.
This phenomenon, known as alternative RNA splicing, often alters the outputs of signaling networks in different tissues and may contribute disproportionately to differences between species, according to a new study from MIT biologists.

After analyzing vast amounts of genetic data, the researchers found that the same genes are expressed in the same tissue types, such as liver or heart, across mammalian species. However, alternative splicing patterns — which determine the segments of those genes included or excluded — vary from species to species."

"Alternative RNA splicing (a discovery for which MIT Institute Professor Phillip Sharp shared the 1993 Nobel Prize in medicine or physiology), controls the composition of proteins encoded by a gene. In mammals, genes — made of DNA stored in the cell nucleus — consist of many short segments known as exons and introns. After the DNA is copied into an RNA transcript, all introns and frequently some exons are excised before the messenger RNA (mRNA) leaves the nucleus, carrying instructions to make a specific protein.

This process allows cells to create a much wider variety of proteins than would be possible if each gene encoded only one protein. Some proteins, including Dscam in fruit flies and neurexin in humans, have thousands of alternate forms. These variant proteins can have vastly different functions, Burge says."

"Because splicing patterns are more specific to each species, it appears that splicing may contribute preferentially to differences between those species, Burge says. “Splicing seems to be more malleable over shorter evolutionary timescales, and may contribute to making species different from one another and helping them adapt in various ways,” he says.

The new study is the first large-scale effort to look at the role of alternative splicing in evolution, says Brenton Graveley, a professor of genetics and developmental biology at the University of Connecticut Health Center. “It provides a lot of new insight into the potential role of alternative splicing in driving differences between species,” says Graveley, who was not involved in this study."

My comment: Alternative RNA splicing is regulated by epigenetic factors and mechanisms, such as DNA methylation profiles, histone epigenetic markers and non coding RNA molecules. Alternative splicing (AS) makes it possible to have alternate forms (The Bible: 'After its kind') from the same organism. This might happen in adaptational events. During and after the AS procedure, NO NEW information is generated, but pre-existing information is regulated, shuffled and re-used along the adaptational needs. Alternative splicing is a basic mechanism in both prokaryotes and eukaryotes. In humans, the AS works like a masterpiece; our cells can produce millions of different proteins just by reading ~19,000 strands of DNA. This kind of use of DNA also points out that DNA is just a passive data base. Evolution never happened. Don't get lost.

Keywords: alternative splicing speciation, alternative splicing phenotypic novelty