biodiversity and its conservation. – introduction to biodiversity – composition of biodiversity...
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Biodiversity and its conservation
Biodiversity and its conservationIntroduction to biodiversityComposition of biodiversityFactors affecting biodiversity
Introduction to Biodiversity
Biological Diversity Coined by wildlife scientist and conservationist Raymond F. DasmannBiodiversity Coined by W.G. RosenThe variation of life forms within a given ecosystem, biome, or for the entire EarthBiodiversity 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 diversitySpecies diversityEcosystem diversity
Genetic DiversityThe 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 diversityNational 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 speciesSurvival and adaptability of a species:When a speciess 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 DiversityThe kind that we are most familiar with represented by incredible variety of different species on the planetAn 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 IndexAn example: D = (n / N)2where 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 DiversityThe 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 DeccanGujarat, Maharashtra, AP and TN
7. The NE states of India
8. The Western GhatsMaharashtra, Karnataka and Kerala
Factors affecting Biodiversity
Immediate causesExploitation 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 causesGlobal trade Pressures of tourismGrowth of human population.Patterns of natural resource and energy consumptionEconomic systems that fail to value the environmentChanges 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 lifeHas devastating effects on native/indigenous species of local ecosystems. A deliberate actRabbits brought over to Australia in 1859 as an additional food sourceAn accidental actRats travelling within ship grain cargoesDumping 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 harvestsEasier to measureIndirect drivers:Indirectly influence the ecosystemChanges in human population, incomes or lifestyle, operate more diffusely, etcIndicators 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 factorsCultural and Religious factorsScience and Technology: Allows increased efficiency in resource useIncreases exploitation of natural resources.
Effect of Direct DriversHabitatLand use changeClimate changePollutionOverexploitationInvasive 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 pressureAffects the structure, function, & biodiversity of the oceans.Major marine accidents
Extent of Cultivated Systems, 2000
In Freshwater ecosystems: Physical changesInvasive speciesPollutionWater 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 waterPollution 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 changesSince small fragments of habitat can only support small populationsTend to be more vulnerable to extinction.
Fragmentation & Flow in Major Rivers
Invasive alien species that establish and spread outside their normal distributionA major cause of extinction.Affected islands and freshwater habitatsEg., In New Zealand, plants have been introduced at a rate of 11 species per year since European settlement in 1840.
Nutrient LoadingIntroduction of nutrients into ecosystems can have both beneficial and adverse effectsBeneficial effects will eventually reach a plateauHarmful 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 biodiversityA 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 evennessSpecies richness the least sophisticatedSimpson indexShannon-Wiener index
Genetic variability, which describes the tendency of genetic characteristics to vary.Frequency-dependent selection is the hypothesis become more common, they become less fit. This is often invoked in host-pathogen interactions, where a high frequency of a defensive allele among the host means that it is more likely that a pathogen will spread if it is able to overcome that allele. *