Introduction

Living organisms are fascinating by its diversity whether it is plants, animals or microbes. A handful of soil is populated with more than the human population on earth. They play important essential roles in nature. So if we arrange these microbes in order or hierarchy by based on its similarity or differences in any characteristics, we can easily get to know and get easy access to all the microbes. So it is desirable to determine the classification. Greek Philosopher Aristotle who is the one classified the living things as plants and animals around 2000 years ago. So in this lecture, we will learn about taxonomy, how is it classifified? What methods are available to classify them? And then brief description about microbial evolution and diversity and its phylogeny.

Taxonomy

Taxonomy [Greek taxis, arrangement, and nomos, law, or nemein, to distribute] is defined as the science of biological classification. In simple term, taxonomy is orderly arranging organisms under study into groups of larger units. It consists of three interrelated parts namely

1. Classification is the arrangement of organisms into groups or taxa (s., taxon) based on mutual similarity or evolutionary relatedness.

2. Nomenclature is concerned with the assignment of names to taxonomic groups in agreement with published rules.

3. Identification is the practical side of taxonomy, the process of determining that a particular isolate belongs to a recognized taxon. (So in short Identify-Naming them and classify them)

Classification

It is bringing order to the diverse variety of organisms present in nature. So there are two general ways the classification can be constructed. First one is based on the morphological characters (phenetic classification) and second is based on evolutionary relationship (phylogenetic classification)

• Phenetic classification - Grouping organisms together based on the mutual similarity of their phenotypic characteristics. It does not provide information about phylogenetic relations.

  Phylogenetic classification- These are systems based on evolutionary relationships rather than external appearance (the term phylogeny [Greek phylon, tribe or race, and genesis, generation or origin] refers to the evolutionary development of a species). It is based on the direct comparison of genetic materials and/or gene product.