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Phylogenetic Analysis - Essay Example

4 pages
850 words
Wesleyan University
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In the case, State of Louisiana V Richard J Schmidt, Dr. Richard Schmidt is accused of a second-degree murder that arises from the allegation that he injected Ms. Janice Trahan with the human immunodeficiency virus. The state contacted experts to carry out a deoxyribonucleic acid (DNA) to compare the HIV found in Ms. Trahan with the HIV found in DM. DM was one of Dr. Schmidt patience who claimed that the doctor has asked for her blood because he wanted to research Hepatitis C around the same time Ms. Trahan claims to have been injected with the virus. Mrs. Sonnies who was an employee at Dr. Schmidt office confirmed that DM blood sample was drawn.

La.Code Evid. Art. 702 provides that, If scientific, technical, or other specialized knowledge will assist in the admissibility of an evidence or testimony should be cross examined by a professional in the area in question .The experts carried out a phylogenetic analysis which showed a close relationship between the HIV found in Ms. Trahan and that found in DM. In this paper, we will discuss in details the phylogenetic tree analysis to help us understand the science and procedure of the analysis. Phylogenetics is therefore a research and analysis of phylogeny. Phylogeny relates to the history and evolution of the taxa of organisms.

Therefore phylogenetic tree analysis scrutinizes the relationship of an organisms nucleotides and protein sequences to others according to the genetic and evolutionary similarities and differences. It also includes the naming and nomenclature of organisms. There are different types of trees with the most common ones being rooted and unrooted trees. The rooted tree provides a close enough result from the data or molecular pattern but does not use a clear out group. On the other hand, the unrooted tree is drawn from rooted nodes to identify a close relationship without making any ancestry assumptions, and they use an out group data.

Phylogenetics, therefore, is a part of the biological systematic, which has a broader scope of forensics, pathogen analysis, and bioinformatics. The report is essentially useful in classification, forensics, and identification of pathogens and in species conservation. The study facilitates classification by providing sequence data that helps to describe the gene pattern relatedness accurately. The public health is heavily invested in the phylogenic as it is one of the tools that they use to identify the origin and composition of pathogens in the bid to control outbreaks. The study has been used by conservatives to make hard policy decisions about species extinction. It also enables forensic analysis to access the DNA evidence in a court case to inform the questions of food poisoning, crime and paternity disputes.

In the analysis, DNA sequencing formulas are used to examine the discernible genetic traits. It also makes use of the tree which shows the hypothetical evolutionary associations of groups of organisms based on the phylogenies of the genus. The tree is used to understand the ecology of the microorganisms.

The approach to carrying out the phylogenetic analysis is contextual and depends on the situation that demands the investigation. It wholly depends on the biological interest of the test. To be able to carry out the research, an individual needs to be vast with topology, branch lengths, nodes and confidence levels of examinations. The general stages of carrying out the analysis are: First, identify the question, like in the case study of the State v Schmidt was to determine if the virus that Ms. Trahans hepatitis C was the same strain that DM had to provide reasonable evidence that Dr. Schmidt intentionally injected her. Then, identify the biological model and parameters that will guide the examination in the direction of answering the question. After the identification of the model, the technicians are required to collect the data that the analysis is based on, for this case; the blood samples of the two individuals were collected.

It is after the collection of the samples that the experts identify the orthologous sequence of the cells of the sample blood or whatever specimen is preferred. The technician then aligns the series of the example which facilitates the examination of the phylogenetic tree and other interest parameters using the sample and model chosen. They then analyze and estimate the error associated with the tree to find out if the examination has answered the question. The technician is supposed to understand the biological sense of the phylogenies carefully. Finally, give the fundamental insights of the phylogenetic.

Advancement in technology in the field of medicine and biology has made it easier for the examination of phylogeny and interpretation of results. The tools available include Ensembl which is a resource that provides identification of the homologous string of a genome, Ensemble Compare that recomputed phylogenies and ClusterW2 phylogeny which estimates the evolutionary tree from various strings alignment.



Graur, Dan, and Wen-Hsiung Li. Fundamentals of Molecular Evolution. Sunderland, Mass: Sinauer Associates, 2000.

Hamilton, Andrew. The Evolution of Phylogenetic Systematics. 2014.

Wiley, E. O., and Tom A. Titus. Phylogenetic Relationships Among Members of the Hybopsis Dorsalis Species Group (Teleostei: Cyprinidae). Lawrence: University of Kansas, 1992.


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