Biodiversity
Biodiversity can be defined as the variety and variability of the living organisms on a particular place or in a particular time.
The biodiversity is of following types:
- Species diversity — The species diversity can be defined as the variety of species found in within a particular area.
- Genetic diversity — The genetic diversity can be defined as the variety of habitats, biotic communities and variety in the composition and structure of the organism.
Floral diversity of Nepal
The variety and variability found among the plants of particular geographical area is called floral diversity.
Nepal is very rich in floral diversity. The occurrences of variety of species of plants in Nepal are given as:
- Lichens: Miehe et al (2015) reported 850 species of lichens in Nepal.
- Fungi: Adhikari (2016) reported 2467 species of fungi in Nepal.
- Algae: Prasad (2013) reported 1001 species of algae in Nepal.
- Bryophytes: Prodhan (2016) listed 1213 species of the Bryophytes in Nepal.
- Pteridophytes: Jenkins et al (2015) have listed 580 species of pteridophytes in Nepal.
- Gymnosperm: Shrestha et al (2018) reported 41 species of Gymnosperm in Nepal.
- Angiosperm: Groambridge and Jenkins (2002) reported 6973 species of flowering plants.
Scope of biodiversity
- It helps to find out the different foods and drinks for human consumption
- It helps in finding of new medicines
- It helps in maintenance of natural beauty
- It helps in conservation of nature, plants and animals.
- It helps in controlling of natural calamities
- It has a great importance as a direct source of income and economic development.
Concept of taxonomy
Taxonomy is the branch of biology that deals with identification, nomenclature and classification of organisms according to their characteristics. It is also known as systematic biology or systematic.
Classification
The classification is the system of arrangement of organism into different groups of their morphology and relationship between the organisms. Some of the systems of classification are discussed below:
- Artificial system of classification — It is developed by Carolous Linnaeus. In this system of classification, the organism are classification into different groups on the basis of one or few visible characters.
- Natural system of classification — It was proposed by Bentham and Hooker. This system of classification was based on the natural relation between the organism.
- Phylogenetic system of classification — It was proposed by Engler and Prantle. This system of classification was based on the evolutionary relationship of the organism.
Binomial nomenclature
The system of giving two names to organism is called binomial nomenclature. It consists of two names i.e. generic name and specific name. The generic name must begin with capital letter and specific name must begin with small letter.
Advantages of binomial nomenclature
- The scientific name of organism is universal and it is recognized throughout the world.
- The nomenclature shows evolutionary relationships among various species under genus.
- It helps in the recognition or identification of newly discovered organisms.
- It indicates a relationship between the different varities of species.
Species
It is the group of organisms which can interbreed freely and can reproduce their offspring of their own kinds.
Genus
It is the group of species having common characteristics.
Taxonomic category
The taxonomic categories are the different hierarchic ranks in the system of classification. Kingdom is the highest taxonomic category, while the species are the lowest taxonomic category.
Taxon
It can be defined as group of organisms belonging to a particular taxonomic category.
Taxonomic hierarchy (hierarchic system of classification)
The arrangement of groups of organisms on different taxonomic categories according to their rank or taxonomic hierarchy is called hierarchical system of classification. Eg: the classification of mustard plant is given below:
- Kingdom: Plantae
- Sub-kingdom: Phenerogame
- Division: Angiospermae
- Class: Dicotyledone
- Sub-class: Polypetales
- Series: Thalamiflora
- Order: Parietales
- Family: Cruciferae
- Genus: Brassica
- Species: Compestines
Two kingdom system of classification
The system of classifying entire living organism into two kingdoms namely plant kingdom and animal kingdom is known as two kingdom system of classification. This system of classification is based on few characteristics of the organisms.
Drawbacks of two kingdom system of classification
- The prokaryotic organism like bacteria and cyanobacteria were placed along with eukaryotic plants in the same kingdom plantae.
- The unicellular protozoans and multicellular animals were placed in the same kingdom animalia.
- The autotrophic algae and heterotrophic fungi were placed in the same kingdom.
- Viruses were not classified.
Five kingdoms system of classification
Due to drawbacks of two kingdom system of classification an American taxonomist R.H Whitaker (1969) has developed five kingdom system.
The principles of five kingdom system of classification are as follows:
- Complexity of cellular organs — Prokaryotic or Eukaryotic
- Complexity of organism — Unicellular or Multicellular
- Mode of nutrition — Autotrophic or Heterotrophic
The five kingdoms are:
- Monera: Prokaryotic, unicellular, autotrophic or heterotrophic e.g. Cyanobacteria & bacteria
- Protista: Eukaryotic unicellular heterotopic. Amoeba, Euglina, Plasmodium.
- Plantae: Eukaryotic, multicellular, autotrophic. e.g. Algae
- Animal: Eukaryotic, multicellular, heterotrophic without cell wall
- Mycota: Eukaryotic, multicellular, heterotrophic with cell wall.