- How is DNA used as evidence for evolution?
- How does DNA provide evidence for evolution?
- Molecular Biological evidence of evolution is reflected from the DNA
- DNA is both Macroevolutionary and Microevolutionary evidence of evolution
- What actually is the role and importance of DNA in evolution?
- Why is DNA useful in tracing evolutionary changes?
How is DNA used as evidence for evolution?
DNA of different species can be compared to see the detailed evidence of evolution. While comparing, the DNA sequence comparisons can show how different species are related together with a lot of matching characteristics indicating that the two different species have evolved from the same ancestral species.
While comparing the DNA it will also show that the different species contain the same genetic code, follow the same basic process of gene expression, codes the amino acids and proteins using the same genetic codes, shows various kinds of random mutation on which various evolutionary forces have acted upon during the course of evolution.
This comparison is a clear-cut evidence that all organisms and different organisms have shared features of the DNA suggesting that all living things are descended from a common ancestor, and that this ancestor had DNA as its genetic material.
If we want to determine which organisms in a group are most closely related then we may need to compare the pieces of DNA (genes) of different organisms. For doing so we can use various different ways of molecular study features, such as the nucleotide sequences of genes.
One of the very famous molecular studies features using the nucleotide sequences of genes is DNA sequencing. In this process, the determination of the sequence of nucleotides (As, Ts, Cs, and Gs) in a piece of DNA is carried on.
A very well-known DNA sequencing technique is the Sanger sequencing technique in which the target DNA is copied many times, making fragments of different lengths. After successful sequencing, the fragments are well-studied and compared to understand the evidence of evolution by looking at the nucleotide sequence patterns.
To utilize DNA as evidence of evolution, scientists sequence related genes found in different species by taking the genes from those species that have the same gene because they inherited it from a common ancestor.
Just for example, if you sequence the gene that encodes insulin from humans, cows, chickens, and chimpanzees each and then you compare the DNA contents, then you will find that although the genes have bit differences but there are also a lot of similarities as well.
As a matter of fact, insulin gene comparison studies done by scientists show that human and chimpanzee insulin genes are 98% identical. On the other comparison case, if you see, chicken and human insulin genes are only about 64% identical.
This shows that humans and chimpanzees are more closely related than humans and chickens as per the evolutionary pieces of evidence are seen after the DNA comparison.
This clearly indicated that the more DNA differences in the genes between two species the more distantly the species are related. While, the fewer DNA differences in the genes, the more closely the species are related.
This shows how DNA is used as evidence for evolution in the field of evolutionary studies.
How does DNA provide evidence for evolution?
DNA is the storehouse of all biological pieces of information in the genetic format that a species can have in its biological body.
DNA had evolved with these genetic pieces of information since the origin of life and is still evolving carrying the same pieces of information with a lot of alteration (mutations) in the present-day species’ body.
DNA is used as the evidence for evolution because it is very important to note that all species on earth have the same genetic code that codes for the same amino acids.
This similarity in the genetic coding indicates that each and every present-day species have evolved from a single ancestral species with a lot of evolution in their biological makeover and body functioning over millions of years of evolution.
To understand this answer let us get it easy with this common example. So yes, we all know that all species on earth have the same gene code for the same proteins and amino acids, just like if we consider the amino acid Cytosine then it is encoded with the same genetic code in all species.
Cytosine is one of the four nucleotides that’s present both in DNA & RNA. Cytosine binds in the double helix opposite a guanine nucleotide.
It is also to be noted that when scientists experimentally replace a gene (DNA) from one species with the same gene (DNA) from a different species, the same amino acids will be produced. This also indicates that the function of that piece of the gene is the same in both of the species indicating that there was a common ancestral relationship between them in the past.
Also at the most basic level, all living organisms share the same functioning of the DNA. They share the same genetic material (DNA), the same, or highly similar, genetic codes, the same process of transcription and translation, and also the same molecular building blocks, such as amino acids.
This clearly and profoundly shows that all of the present-day organisms share these features because they were inherited from the ancestor via. genes (made of DNA) over the millions of years of evolution after a lot of random mutations and other evolutionary forces being acted on the DNA and its contents.
So, it can be said that DNA and the genetic code reflect the shared ancestry of life. And so, DNA used as evidence for evolution.
Molecular Biological evidence of evolution is reflected from the DNA
In Molecular Biology, the composition, structure, and interactions of nucleic acids (DNA & RNA) and the proteins they produce in the biological body are studied with detailed analysis and experimentation.
In the field of evolution too, molecular biological studies have contributed a lot. There’s a very close relation between molecular biology and evolution in the field of evolutionary studies.
The relationship between molecular biology and evolution is that in molecular biology we study the sequence composition of DNA, RNA, and proteins across generations. This generates ideas of evolutionary changes in the organism.
The ideas of the various evolutionary changes can be researched in the field of molecular evolution by utilizing various principles of evolutionary biology and population genetics to explain patterns in these evolutionary changes.
When the genetic materials (DNA) of different species are compared using the techniques of molecular biology, then it is well-seen that the DNA and the genetic code reflect the shared ancestry of life between the different species.
The DNA as the genetic material being universal to all life forms on earth shows near universality of the genetic code and the machinery of DNA replication and expression as well. This is proven by doing the molecular biological studies of the genetic materials.
The level of DNA sequence comparison and matching between different species can show how related species are.
The evolutionary changes that occur in the DNA cause the formation of all new proteins and functions for proteins that commonly occurs after gene duplication events. Such cause differentiates one species from the other which can be seen when comparing the DNA sequences via. molecular biological techniques.
And so, that’s why it’s said that the Molecular Biological evidence of evolution is reflected from the DNA.
DNA is both Macroevolutionary and Microevolutionary evidence of evolution
Microevolutionary changes are those evolutionary changes that happen on a small scale within a small timeframe. On the other hand, macroevolutionary changes are those changes that happen on a large scale within a large time frame.
We can relate microevolutionary changes to that of small evolutionary changes happening in a small population. On the other hand, we can relate the macroevolutionary changes to that of grand evolutionary changes that transcend the boundaries of a single species or population.
Let it be microevolution or macroevolution, both happen at the same molecular level i.e. both rely on the same established mechanisms of evolutionary change called mutation.
And, mutations happen because of DNA copying mistakes made during cell division, exposure to ionizing radiation, exposure to mutagens, or due infection by viruses. Mutations cause changes in the DNA sequence at the molecular level.
So, due to mutation, there do occurs various molecular evolutionary changes in the DNA on the micro (small-scale). The micro (small-scale) evolutionary changes gather together one after the other over a large time frame adding-up to create a macro (large-scale) evolution.
So, microevolutionary changes usually force changes in one or a few genes and happen in small populations over shorter timescales. Various microevolutionary changes at once may definitely cause macroevolutionary changes that will occur over extended time periods causing the formation of new species and groups.
And so, both microevolutionary and macroevolutionary changes can be well-seen or studied at the molecular level in the DNA.
So, that’s why it is said that DNA is both the macroevolutionary and microevolutionary evidence of evolution.
NOTE: Microevolution and macroevolution aren’t really two different processes. They’re the same process causing evolution and are occurring on different timescales. Microevolutionary processes occurring over thousands or millions of years can add up to large-scale changes that define new species or groups.
What actually is the role and importance of DNA in evolution?
DNA has a close relationship with evolution. The ways biological organisms had evolved in the past, have evolved so far, or will be evolving in the future are all stored and governed by the DNA at the molecular level.
Other evolutionary factors like genetic drift, gene flow, natural selection, mutation, etc. cause the genotypic evolutionary changes in the DNA either directly or indirectly that are to be seen phenotypically in the organisms’ body.
Genes that carry the genetic data from one generation to the other is made up of DNA. This DNA gives the genes its ability to replicate repeatedly and pass on to the next generation. Therefore forwarding the genetic evolutionary information from one generation to the next.
DNA due to its better stability than RNA is successfully able to store the evolutionary genetic information and can also get copied multiple times with only a few replication errors. Its stable nucleotide structure containing base, sugar, and phosphate makes it a good source to carry the genetic information over generations while balancing the happening of the various micro and macro evolutionary changes over time.
DNA structure is actually due to a fine balance of interactions including hydrogen bonds between bases, hydrogen bonds between bases and surrounding water molecules, and base-stacking interactions between adjacent bases. Such chemical stability also makes the DNA better stable and protective while transferring the evolutionary information for many generations.
Mutations (both beneficial and detrimental mutations) arise while there is an error while copying DNA. Mutation actually creates new genetic variation in a gene pool. It is how all new alleles first arise. Mutation happens in the DNA and it provides the genetic variation needed for other forces of evolution like natural selection, etc. to act.
Also, that DNA is important for inheritance, protein production, and is the chief genetic instruction guide for life and its various processes to happen.
So, it is the DNA that has the ability and to control and encode the instructions for an organism’s or each cell’s growth and development and reproduction and ultimately death. So, this chief genetic instruction guide i.e. the DNA holds all of the evolutionary information in the organism.
Overall if you see, the structure of DNA, organization and regulation of genes in DNA, transcription and translation of the DNA, other necessary mechanisms of gene expression that make RNA and then proteins according to the instructions coded in DNA, have huge impacts on how evolution functions.
Why is DNA useful in tracing evolutionary changes?
If we study at the molecular biological level, then the study of DNA and its sequence composition provides a lot of evolutionary pieces of evidence about the organism.
DNA is the place where mutations do occur. DNA being a very stable molecule allows the evolutionary force of mutations to take place in the DNA at a certain constant rate making the DNA best for studying the evolutionary traces.
Also if you see from the phylogenetic biological point of view then you will find that the study of a lot of phylogenetic events and other evolutionary traces of fossils are determined from the DNA.
The genetic information that is stored in the DNA gives clear-cut and precise information about the organism’s behavior, physiology, and genetic makeover as well. So, studying the DNA can give a clear understanding of the evolutionary origin of the organisms and their lineage determination.
By studying the DNA sequence, molecular biologists and scientists can determine a protein’s amino acid sequence and protein production method. These data can be compared with other organisms’ DNA data to check if they share any closely related genes or even identical amino acid sequences.
DNA is also helpful in studying the divergent and convergent evolution based on studying the homologous organs of the organisms. This is so because species may share similar physical features because the feature was present in a common ancestor and that can be traced both from the DNA and organs physiology.
Comparing the strands of DNA and by knowing its genetic code scientists can show how related species are. And yes, that’s also why it is said that DNA and the genetic code reflect the shared ancestry or ancestral lineage of life.
The study of DNA is very very much perfect and is the most significant process in studying and tracing the evolutionary changes in an organism.