Biodiversity and Types of Biodiversity
Chapter no: 01
Biodiversity
The biological diversity may be defined as ‘the variability of organisms’.
Biodiversity includes the genetic variability (for which different varieties of
species have appeared in the course of evolution) and diversity of life forms
on earth, such as plants, animals, microorganisms, etc., living in a wide range
of ecosystems. Diversity among species and between organisms of the same
species
Levels of biodiversity: Generally, it deals with three hierarchical levels.
Genetic diversity:
It describes the variation in the number and types of genes within species and
populations. Genetic variation arises from gene and chromosome mutations in
individuals and in sexually reproducing organisms. Genetic diversity in the
population is determined by the recombination of genetic materials during cell
division after sexual reproduction.
Importance of Genetic Diversity:
1. The origin of a new species or speciation is the product of genetic
diversity.
2: It is useful in adaptations to changes in environmental conditions.
3: It is important for agriculture productivity and development.
Species diversity:
It describes all species on earth. It includes the variety and abundance of
living organisms in a region or all over the world. The estimated number of
species is 30–50 million. The species diversity in the land ecosystem decreases
with increasing altitude.
Importance:
1: It reflects the entire range of evolutionary and ecological adaptations of
species to the environment.
2: It provides people with resources such as food, shelter, medicines, etc.
Species richness (variety):
The definition of species richness is described as
total number of species per unit area’. An important factor that can bring
about changes in species richness is climate change. Species richness is
greater in equatorial regions than in the polar region.
Species evenness:
The distribution of individuals among species in a community represents species
evenness.
If there are 40 foxes and 1000 dogs, the community is not even.
Special abundance (number): This refers to the
‘number of individuals per species’.
If one species is represented by 96 individuals, while the rest are represented
by 1 species each, this shows low diversity.
Endemic species;
‘when a species is confined entirely to a particular area’ It is termed an
endemic species.
Ecosystem diversity:
It refers to variety in both terrestrial and aquatic ecosystems. It includes
varieties of habitats, biotic communities, and ecological processes in the
biosphere.
Importance of ecosystem diversity:
- It provides crucial services to humans, such as
- Water for drinking and agriculture
- Flood control
- Protection from soil erosion
- Filtering of air and water
Functional Diversity:
It refers to a variety of biological processes, functions, or characteristics
of a particular ecosystem, in this case, marine biodiversity. Functional biodiversity
reflects the biological complexity of an ecosystem.
Taxonomic diversity:
This diversity considers the genetic relationships between different groups of
species.
Measuring biodiversity:
It means to determine the number of species in a specific area.
In Pakistan, there is no institution for the calculation of new inventory
species, the measurement of biodiversity, or the monitoring system for the
identification of species. Due to a lack of quantitative and qualitative
information about biodiversity, at present we know little about the
biodiversity of the mountains of Pakistan.
According to Whittaker (1972), community diversity is measured on three
scales.
Alpha diversity:
- It describes the number of species within a small or local area.
- Alpha community tells us about the species diversity in a specific community.
- It depends on species richness and evenness within a habitat unit.
- Beta diversity:
- It describes an expression of diversity between habitats (it links alpha and gamma diversity).
- It reflects the variety of species in an area.
- It also describes a range of communities due to the replacement of species that arises due to the presence of different microhabitats, niches, and environmental conditions.
Gamma diversity:
It describes diversity in the number of species over a total land area or
geographical area.
Example
Alpha diversity is the richness and evenness of individuals within a habitat
unit. For example, the alpha diversity of sites A = 7 species, B = 5 species,
and C = 7 species
Beta species is an expression of diversity between habitats. In the example,
the greatest beta diversity is observed between Sites A and C, with 10 species
that differ between them; only two species are common.
Gamma diversity is landscape diversity within a landscape or region.
The gamma diversity is three habitats with 12 species.
Gamma diversity can be calculated using this formula:
Gamma=S1+S2-C
S1 is the total number of species in Site 1.
S2=total numbers of species in site 2
total numbers of species that are common
The importance of biodiversity
Productive values:
Biodiversity produces a number of products harvested from nature and sold in
the commercial market. Indirectly, it provides economic benefits to people,
including water quality, soil production, scientific research, recreation, etc.
Consumptive values:
It can be assigned to goods such as fuel, wood, leaves, forest products, etc.
that may be consumed locally and do not figure in national and international
markets.
Social values:
The loss of biodiversity directly influences social life, possibly through
influencing ecosystem functions (energy flow and biogeochemical cycles, global
warming, and acid rain).
Aesthetic value:
Aesthetic values such as the refreshing fragrance of flowers, the taste of
barriers, the melodious songs of birds, etc. compel human beings to preserve
them because they derive great enjoyment from the natural environment.
Similarly, botanical zoological gardens are a means of biodiversity
conservation and have aesthetic values.
Ethical values:
Every organism has an inherent right to exist, regardless of whether it’s
valuable to human beings or not. It should be the prime responsibility and
moral obligation of man to preserve and conserve other organisms, which will
directly or indirectly favor the existence of man.
Ecological values:
- Biodiversity maintains the integrity of the environment through:
- Maintaining CO2 and O2 balance
- Regulation of biogeochemical cycles
- Absorption and degradation of pollutants
- Regulation of the climate
Economic values:
Biodiversity has great economic value because economic development depends on the efficient and economic management of biotic resources.
Legal values:
Since earth is the homeland of all living
organisms, all have an equal right to coexist on its surface with all its
benefits. Unless some legal value is attached to biodiversity, it will not be
possible to protect the rapid extinction of species.
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