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

• 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 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; 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:

• Allows increased efficiency in resource use• Increases exploitation of natural resources.

Effect of Direct Drivers

• 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– Invasive species– Pollution– Water withdrawals from rivers and lakes for

irrigation or urban or industrial use increased 6-fold 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.

• Species Diversity is the Simpson's diversity index, which uses the following formula:

• 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