Question

Molecular phylogenetics revolutionized our understanding of the evolution of focal taxa; why are molecular genetic variants so useful for achieving new phylogenetic inferences?

Answer 1

Answer:

Molecular phylogenetics: A set of techniques that allow evolutionary relationships between DNA sequences and inferred by making comparision between those sequences.

Objectives:

• Due to accumulation of mutations genomes evolve gradually, then the amount of difference in nucleotide sequence between a pair of genomes should indicate how recently those two genomes shared a common ancestor.

• By analyzing those changes and comparing three or more genomes which is helpful in the evolutionary relationships between them.

  Upto late 1960’s the techniques are used by collecting data through indirect assessment methods:

1. Immunological data

2. Protein electrophoresis

3. DNA hybridization data

• During 1980’s DNA based phylogenetics began to be carried out on a large scale.
• Due to some limitations of indirect assessment methods, DNA sequence analysis is used which provides more novel information.
• Still today Protein sequences are used in some cases, but DNA is the predominant molecule because DNA yields more phylogenetic information than protein, the nucleotide sequences of a pair of homologous genes having a higher information content than the amino acid sequences of the corresponding proteins, because mutations that result in non-synonymous changes alter the DNA sequence but do not affect the amino acid sequence.
• By DNA sequence analysis, samples can be prepared by PCR shows good results of variability in both the coding and non-coding regions of the genome can be examined which obtains novel information.

Benefits:

• By using PCR gives accurate and good results which plays an important role of DNA in modern molecular phylogenetics.
• DNA molecules provides the most detailed data for molecular phylogenetics with out any confusion.

Denitions:

Taxa: A Taxa is any taxonomic unit. It is of eight types.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. With each step down in classification, organisms are split into more and more specific groups.

Eg: The class Mammalia is a taxon which includes all mammalian species. Similarly, a species is a taxon.

DNA: Deoxyribonucleic acid, one of the two forms of nucleic acid in living cells, the genetic material for all cellular life forms and many viruses.

Genome: This is a whole of its hereditary information encoded in its DNA, RNA of (some viruses). This includes both the genes and non-coding sequences of DNA.