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Biodiversity and its conservation
• Biodiversity and its conservation
– Introduction to biodiversity
– Composition of biodiversity
– Factors affecting biodiversity
Introduction to Biodiversity
• “Biological Diversity” – Coined by wildlife scientist
and conservationist Raymond F. Dasmann
• “Biodiversity” – Coined by W.G. Rosen
• The variation of life forms within a given
ecosystem, biome, or for the entire Earth
• Biodiversity found on Earth today consists of
many millions of distinct biological species – the
product of nearly 3.5 billion years of evolution
A textbook definition:
The variation of life
at all levels of biological organization
For biologists,
“Biological diversity" or “Biodiversity“ –
“Totality of genes, species & ecosystems of a region".
This definition describes most circumstances and
presents a unified view of the traditional 3 levels at
which biological variety has been identified:
– Genetic diversity
– Species diversity
– Ecosystem diversity
Genetic Diversity
• The level of diversity referring to the total number of
genetic characteristics in the genetic makeup of a
species.
• Difference from genetic variability…???
• Population Genetics: many hypotheses & theories reg
genetic diversity.
– Neutral Theory of Evolution: Diversity is due to
accumulation of neutral substitutions.
– Diversifying Selection Hypothesis: Two subpopulations of a
species live in different environments that select for
different alleles at a particular locus.
– Frequency-dependent Selection Hypothesis
• Importance of genetic diversity
– National Science Foundation: “Diversity within a species
is necessary to maintain diversity among species, and
vice versa.”
– “If any one type is removed from the system, the cycle can break
down, and the community becomes dominated by a single
species”
– Survival and adaptability of a species:
When a species’s environment changes, slight gene
variations are necessary for it to adapt and survive.
A species with large degree of genetic diversity among
its population will have more variations from which to
choose the most fit alleles.
Species with very little genetic variation are at a great
risk.
Species Diversity
• The kind that we are most familiar with – represented by
incredible variety of different species on the planet
• An index that incorporates the number of species in an
area and their relative abundance.
• Most common index of species diversity is a family of
equations called Simpson's Diversity Index
• An example: D = (n / N)2
where “n”: Total no. of organisms of a particular species
“N”: Total no. of organisms of all species.
“D”: Value of diversity.
D ranges between 0 and 1; where 1 is the richest
ecosystem
• Humans have a huge effect on species
diversity. Main reasons:
- Destruction, Modification, and/or
Fragmentation of Habitat
- Introduction of Exotic Species
- Overharvest
- Global Climate Change
Ecosystem Diversity
• The diversity of a place at the level of
ecosystems.
• An ecosystem is the result of all the biological,
climatic, geological and chemical "ingredients"
in a particular area.
Biogeographic classification of India
1. Trans-Himalayan region
of Ladakh
2. The Himalayan Ranges and valleys of
Kashmir, HP, Uttarkhand, Assam & NE states
3. Terai Region –
lowlands where Himalayan rivers enter the plains
The TERAI Region
4. The Gangetic and Brahmaputra Plains
The fertile Gangetic Plains
5. The Thar Desert of Rajasthan
The Thar Desert
6. The semi-arid grasslands of the Deccan
Gujarat,
Maharashtra, AP
and TN
7. The NE states of India
8. The Western Ghats
Maharashtra,
Karnataka and Kerala
Factors affecting Biodiversity
Immediate causes
• Exploitation of wild living resources, including hunting
and wildlife trading
• Expansion of agriculture, forestry and aquaculture
• Expansion of transport systems and building
• Habitat loss; especially coral reefs, wetlands, primary
forests and coastlines - all vulnerable and with great
biodiversity
• Species introductions
• Pollution of soil, water and atmosphere
• Environmental factors - Global climate change, rainfall,
etc... The harsher, the less biodiversity….
Underlying causes
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Global trade
Pressures of tourism
Growth of human population.
Patterns of natural resource and energy consumption
Economic systems that fail to value the environment
Changes in human social organization, including loss of
indigenous cultures
• Inequality in ownership, management and flow of
benefits from the use and conservation of biological
resources
How humans move around life…
• Has devastating effects on native/indigenous species of local
ecosystems.
• A deliberate act
– Rabbits brought over to Australia in 1859 as an additional food source,
• An accidental act
– Rats travelling within ship grain cargoes
– Dumping of ballast water by ships containing small marine organisms.
• Islands and aquatic counterparts (fresh or salt water lakes), most
vulnerable to species extinctions.
– Introdn of predatory Nile perch as an extra protein rich food source to
Lake Victoria in Africa have reduced the original 350+ varieties of fish
by 50%.
A driver…!!!
• DRIVER: Natural or human-induced factor that directly
or indirectly cause a change in biodiversity.
• Direct drivers:
– Explicitly influence ecosystem processes.
– Include land use change, climate change, invasive species,
overexploitation, and pollution.
– Fertilizer usage, water consumption, irrigation, and harvests
– Easier to measure
• Indirect drivers:
– Indirectly influence the ecosystem
– Changes in human population, incomes or lifestyle, operate
more diffusely, etc
– Indicators are not as well developed and measurement data
is less readily available.
• Changes in biodiversity are driven by
combinations of drivers that work over time,
on different scales, and that tend to amplify
each other.
• For example, population and income growth
combined with technological advances can
lead to climate change.
• Five major indirect drivers that influence
biodiversity are:
– Change in Economic activity: Global economic activity
is now nearly seven times what it was 50 years ago
and it is expected to grow further; The concept of
globalization….
– Population change: World population has doubled in
the past forty years, reaching 6 billion in 2000. The
fact that more and more people live in cities increases
the demand for food and energy and thereby
pressures on ecosystems.
– Socio-Political factors
– Cultural and Religious factors
– Science and Technology:
• Allow s increased efficiency in resource use
• Increases exploitation of natural resources.
Effect of Direct Drivers
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Habitat
Land use change
Climate change
Pollution
Overexploitation
Invasive species
• In Terrestrial ecosystems:
– Land cover change, mainly by conversion to cropland.
– Only non-arable areas (deserts, boreal forests, tundra)
remain relatively intact…!!!
• In Marine ecosystems:
– Fishing - major direct human pressure
– Affects the structure, function, & biodiversity of the
oceans.
– Major marine accidents
Extent of Cultivated Systems, 2000
• In Freshwater ecosystems:
– Physical changes
– Modification of water regimes
– Invasive species
– Pollution
– Water withdrawals from rivers and lakes for
irrigation or urban or industrial use increased
sixfold since 1900.
– Increased discharge of nutrients causes intensive
eutrophication and potentially high levels of
nitrate in drinking water
– Pollution from point sources such as mining
Some specific direct drivers affecting
biodiversity….
• Natural disturbances (such as fires) or
changes in land use (such as road
construction) lead to the fragmentation of
forests.
– Leads to habitat changes
– Since small fragments of habitat can only support
small populations
– Tend to be more vulnerable to extinction.
Fragmentation & Flow in Major Rivers
• Invasive alien species that establish and
spread outside their normal distribution
– A major cause of extinction.
– Affected islands and freshwater habitats
– Eg., In New Zealand, plants have been introduced
at a rate of 11 species per year since European
settlement in 1840.
• Nutrient Loading
– Introduction of nutrients into ecosystems can
have both beneficial and adverse effects
– Beneficial effects will eventually reach a plateau
– Harmful effects will continue to grow.
– The total amount of reactive, or biologically
available, nitrogen created by human activities
increased ninefold between 1890 and 1990.
Measurement of biodiversity
• A variety of objective measures for “empirical
measurement” of biodiversity.
• Each measure of biodiversity relates to a
particular use of the data.
• Biodiversity is plotted as taxonomic richness of a
geographic area, with some reference to a
temporal scale.
• Whittaker: 3 common metrics used to measure
species-level biodiversity, encompassing
attention to species richness or species evenness
– Species richness – the least sophisticated
– Simpson index
– Shannon-Wiener index