BIO – DIVERSITY & ITS CONSERVATION
PART 1
• The term 'biodiversity' refers to 'the variety and variability among living organisms and the ecological complexes in which they occur'.
• If you observe a patch of forest, you may find a wide variety of plant and animal life.
• The plant life may range form a small herb to a large tree, and animal life may vary from a tiny insect to a large mammal.
• Apart from plants and animals, numerous microorganisms, which cannot be seen with naked eyes also occur in the soil.
• This shows biological diversity or biodiversity of a forest patch. Thus, biodiversity can be defined as 'the totality of genes, species and ecosystem of a region'.
• Biodiversity differs from place to place as each habitat has its distinct biota.
• However, many biologically rich and unique habitats are being destroyed, degraded and fragmented.
• The major factors that tend to decrease biodiversity are increasing human population, higher resource consumption and pollution.
• Loss of biodiversity reduces gene pool of species, number of interactions in the biota and ability of species to adapt themselves to changes in the environment.
• It not only checks evolutionary advancements but also put the surviving species to dangers of extinction.
MAGNITUDE OF BIODIVERSITY:
• Biologists are enganged in the identification and naming of species for the last 250 years.
• Still, they are able to name and describe for less number of species than the actual number present. Presently, the known and described number of species of all organisms on the earth is between 1.7 and 1.8 million, which is fewer than 15% of the actual number.
• It is predicted that the number of total species varies from 5 to 50 million. Approximately 61% of the known species are insects.
• About 2,70,000 species of plants and only 4650 species of mammals are known to science.
• Only fragmentary information is available about bacteria, viruses, protists and Archaea.
• The major area where numerous species are believed to be unknown to science are tropics and coral reefs.
• Presently, efforts are being made to discover and describe new species more rapidly.
• The projects like 'Global Biodiversity Information Facility and the Species 2000’, are attempting to discover new species faster than ever before.
LEVELS OF BIODIVERSITY :
• The biological diversity include three interrelated hierarchical levels, viz. Genetic diversity, Species diversity and Community and ecosystem diversity.
I. Genetic diversity :
• It is the diversity in the number and types of genes as well as chromosomes present in different species and the variations in the genes and their alleles in the same species.
• For instance, the number of genes is about 450-700 in Mycoplasma, 4000 in Escherichia coli, 13000 in Drosophila melanogaster, 32000-50000 in Oryza sativa and 35000 to 45000 in Homo sapiens sapiens.
• 'The genetic variation existing within a species is called genetic diversity’.
• The genetic variation may be in alleles (different variants of same genes), in entire genes (the traits determining particular characteristies) or in chromosomal structures.
• Genetic diversity is useful in adaptation to changes in environmental conditions.
• It helps in speciation or evolution of new species. Lower genetic diversity within a species or variety may be useful for uniformity in yield as well as higher yield.
• However, it is liable to undergo degradation and prone to mass scale destruction at the hands of fungal or insect attacks.
II. Species diversity :
• It is the variety in the number and richness of the species of a region. The number of species per unit area is called species richness.
• Number of individuals of different species represent species evenness or species equitability. Communities where species are represented by more or less equal number of individuals exhibit evenness.
• Others where one or more species have more individuals than others show dominance or unevenness.
• Species diversity is product of both species richness or evenness or equitability, i.e., species richness weighed by species evenness.
• Odum et al (1960) calculate species diversity (d) as number of species per thousand individuals while Menhinick (1964) calculates it as number of species in relation to square root of total number of individuals.
• Diversity index commonly used in ecological studies is Shannon index.
III. Community and ecosystem diversity :
• Community diversity refers to the variations in the biological communities in which species live.
• There are three perspectives of diversity at the level of community. These are alpha diversity, beta diversity and gamma diversity.
a) Alpha diversity (a-index Diversity, Within-Community Diversity) : It indicates diversity within the community. It refers to the diversity of organisms sharing the same community or habitat. A combination of species richness and equitability/evenness is used to represent diversity within a community or habitat.
b) Beta diversity (b-index Diversity, Between-Community Diversity) : It is biodiversity which appears in a range of communities due to replacement of species with the change in community/habitat due to presence of different microhabitats, niches and difference in environmental conditions.
c) Gamma diversity (g-index Diversity) : It refers to the diversity of the habitats over the total land scape or geographical area.
• Ecosystem diversity refers to the variation in the structure and functions of the ecosystem.
• It describes the number of niches, trophic levels and various ecological processes that sustain energy flow, food webs and the recycling of nutrients.
• It has focus on various biotic interactions and the role and function of keystone species (Species determining the ability of large number of other species to persist in the community).
• Diversity helps in producing more productive and stable ecosystems/communities which can tolerate various stresses like prolonged drought.
• If you observe a patch of forest, you may find a wide variety of plant and animal life.
• The plant life may range form a small herb to a large tree, and animal life may vary from a tiny insect to a large mammal.
• Apart from plants and animals, numerous microorganisms, which cannot be seen with naked eyes also occur in the soil.
• This shows biological diversity or biodiversity of a forest patch. Thus, biodiversity can be defined as 'the totality of genes, species and ecosystem of a region'.
• Biodiversity differs from place to place as each habitat has its distinct biota.
• However, many biologically rich and unique habitats are being destroyed, degraded and fragmented.
• The major factors that tend to decrease biodiversity are increasing human population, higher resource consumption and pollution.
• Loss of biodiversity reduces gene pool of species, number of interactions in the biota and ability of species to adapt themselves to changes in the environment.
• It not only checks evolutionary advancements but also put the surviving species to dangers of extinction.
MAGNITUDE OF BIODIVERSITY:
• Biologists are enganged in the identification and naming of species for the last 250 years.
• Still, they are able to name and describe for less number of species than the actual number present. Presently, the known and described number of species of all organisms on the earth is between 1.7 and 1.8 million, which is fewer than 15% of the actual number.
• It is predicted that the number of total species varies from 5 to 50 million. Approximately 61% of the known species are insects.
• About 2,70,000 species of plants and only 4650 species of mammals are known to science.
• Only fragmentary information is available about bacteria, viruses, protists and Archaea.
• The major area where numerous species are believed to be unknown to science are tropics and coral reefs.
• Presently, efforts are being made to discover and describe new species more rapidly.
• The projects like 'Global Biodiversity Information Facility and the Species 2000’, are attempting to discover new species faster than ever before.
LEVELS OF BIODIVERSITY :
• The biological diversity include three interrelated hierarchical levels, viz. Genetic diversity, Species diversity and Community and ecosystem diversity.
I. Genetic diversity :
• It is the diversity in the number and types of genes as well as chromosomes present in different species and the variations in the genes and their alleles in the same species.
• For instance, the number of genes is about 450-700 in Mycoplasma, 4000 in Escherichia coli, 13000 in Drosophila melanogaster, 32000-50000 in Oryza sativa and 35000 to 45000 in Homo sapiens sapiens.
• 'The genetic variation existing within a species is called genetic diversity’.
• The genetic variation may be in alleles (different variants of same genes), in entire genes (the traits determining particular characteristies) or in chromosomal structures.
• Genetic diversity is useful in adaptation to changes in environmental conditions.
• It helps in speciation or evolution of new species. Lower genetic diversity within a species or variety may be useful for uniformity in yield as well as higher yield.
• However, it is liable to undergo degradation and prone to mass scale destruction at the hands of fungal or insect attacks.
II. Species diversity :
• It is the variety in the number and richness of the species of a region. The number of species per unit area is called species richness.
• Number of individuals of different species represent species evenness or species equitability. Communities where species are represented by more or less equal number of individuals exhibit evenness.
• Others where one or more species have more individuals than others show dominance or unevenness.
• Species diversity is product of both species richness or evenness or equitability, i.e., species richness weighed by species evenness.
• Odum et al (1960) calculate species diversity (d) as number of species per thousand individuals while Menhinick (1964) calculates it as number of species in relation to square root of total number of individuals.
• Diversity index commonly used in ecological studies is Shannon index.
III. Community and ecosystem diversity :
• Community diversity refers to the variations in the biological communities in which species live.
• There are three perspectives of diversity at the level of community. These are alpha diversity, beta diversity and gamma diversity.
a) Alpha diversity (a-index Diversity, Within-Community Diversity) : It indicates diversity within the community. It refers to the diversity of organisms sharing the same community or habitat. A combination of species richness and equitability/evenness is used to represent diversity within a community or habitat.
b) Beta diversity (b-index Diversity, Between-Community Diversity) : It is biodiversity which appears in a range of communities due to replacement of species with the change in community/habitat due to presence of different microhabitats, niches and difference in environmental conditions.
c) Gamma diversity (g-index Diversity) : It refers to the diversity of the habitats over the total land scape or geographical area.
• Ecosystem diversity refers to the variation in the structure and functions of the ecosystem.
• It describes the number of niches, trophic levels and various ecological processes that sustain energy flow, food webs and the recycling of nutrients.
• It has focus on various biotic interactions and the role and function of keystone species (Species determining the ability of large number of other species to persist in the community).
• Diversity helps in producing more productive and stable ecosystems/communities which can tolerate various stresses like prolonged drought.
To be Continued in Part 2
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