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The secret of the gene tree: How to use DNA to reveal the evolutionary history of organisms?
In the field of biological sciences, the study of gene trees is gradually revealing the mystery of life evolution. Through molecular phylogenetics, scientists use genetic molecular differences in DNA sequences to gain a deeper understanding of the evolutionary relationships between different species. This analysis not only advances our understanding of biodiversity, but also helps us draw a huge evolutionary tree and explore the origin of life.
Molecular phylogenetics provides a powerful tool to redefine the classification and evolution of organisms by analyzing DNA.
History of Molecular Phylogenetics
The theoretical framework of molecular phylogenetics dates back to the 1960s, when scientists began exploring the use of molecular data to explain the relationships between species. Emile Zuckerkandl, Emanuel Margoliash, Linus Pauling, and Walter M. Fitch, among others, paved the way for the field. Subsequently, research on owls, reptiles and apes gradually expanded the application of this field. Especially between 1974 and 1986, DNA-DNA hybridization technology became the mainstream method for measuring genetic differences.
Theoretical Background
Early molecular phylogenetics, also called chemotaxonomy, focused on the isolation and characterization of proteins, enzymes, and other molecules. However, with the advent of DNA sequencing technology, this method has gradually been replaced. DNA sequencing can not only accurately obtain the order of nucleotide arrangement, but also show the pattern of changes during evolution. Although whole-genome sequence analysis remains cumbersome and costly, sequence analysis within specific chromosomal regions has become relatively feasible.
"The variation in gene sequences reflects the history of species in their long evolution."
Technology and Applications
All living things contain deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Often, closely related species share a high degree of similarity in the structures of these molecules. Molecular clocks assume that the time of divergence of species can be estimated by accumulating mutations. Since the invention of Sanger sequencing in 1977, scientists have been able to analyze and identify molecular structures in living things. With the development of high-throughput sequencing technology, new applications such as DNA barcoding and genetic fingerprinting have gradually become concrete. These technologies are of great significance to species identification and forensic medicine.
Molecular phylogenetic analysis
Performing a molecular phylogenetic analysis typically involves five major steps. The first step is to obtain the sequence, followed by multiple sequence alignment, which is the basis for constructing a gene tree. The third step is to select appropriate DNA and amino acid substitution models. Finally, the tree structure is established according to different methods and the credibility of the tree is evaluated. MEGA is a widely used free analysis software that can effectively help researchers perform these analyses and provide reliable results for molecular phylogenetics.
"By analyzing genetic differences, we can depict the intricate relationships between species."
Limiting Factors
While the development of molecular phylogenetics has provided powerful tools, it also has limitations. This approach is based on the assumption that classification must be consistent with evolutionary relationships, which makes it difficult to reconstruct an optimal phylogenetic tree. In addition, the discovery of horizontal gene transfer challenges traditional molecular phylogenetic methods, indicating that different genes within the same organism may have different evolutionary trees. This requires scientists to be more cautious when conducting analyses and to consider all possible variables.
ConclusionWith the advancement of science and technology, molecular phylogenetics is gradually opening our journey of exploration into a series of complex issues in the evolution of life. Through DNA sequence analysis, we can glimpse the profound mysteries of the history of life and gain a deeper understanding of the formation and changes of biodiversity. In the future, will we be able to use these technologies to better predict the evolutionary trends of species and the impact of environmental changes?
