biology-class-12-unit-15-chapter-01-diversity-of-living-organisms-lecture-1-3-fpawduoccbq

<h4 id="successthis-chapter-will-give-you-insights-on-questions-such-assuccess"><Success>This chapter will give you insights on questions such as</Success></h4>
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<ul>
<li>Why are there so many species?</li>
<li>Did such great diversity exist throughout earth’s history?</li>
<li>How did this diversification come about?</li>
<li>How and why is this diversity important to the biosphere?</li>
<li>Would it function any differently if the diversity was much less?</li>
<li>How do humans benefit from the diversity of life?</li>
</ul>
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<h3 id="successbiodiversitysuccess"><Success>Biodiversity</Success></h3>
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<p>Biodiversity ~ 1980’s</p>
<p>variety/Vasiations/Variability of living organizms</p>
<p>Biological + Diversity</p>










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<h3 id="successbiodiversitysuccess-1"><Success>Biodiversity</Success></h3>
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<ul>
<li>Biodiversity is the variety and variability of different types of life found on the Earth and the variations within species.</li>
<li>The term ‘Biodiversity’ was coined by Walter $G$ Rosen and popularised by Edward Wilson, the sociobiologist in 1980’s</li>
<li>More than 20,000 species of ants.</li>
<li>More than 3,00,000 species of beetles.</li>
<li>More than 28,000 species of fishes.</li>
<li>More than 20,000 species of orchids.</li>
<li>More than 2,81,621 species of vascular plant.</li>
<li>a More than 9,990 species of birds.</li>
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<h3 id="successlevels-of-biodiversitysuccess-1"><Success>Levels of biodiversity</Success></h3>
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<p><strong>Genetic Diversity</strong></p>
<ul>
<li>Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species</li>
<li>Gene is the basic functional unit, made up of nucleotide which is made up of nitrogenous base (ATGC), which helps in variation</li>
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<h3 id="successgenetic-diversitysuccess"><Success>Genetic diversity</Success></h3>
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<ul>
<li>Levels of biodiversity</li>
</ul>
<ol>
<li>Genetic Diversity-Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species</li>
</ol>
<ul>
<li>
<p>For example- Rauwolfia vomitoria shows genetic variations in terms of potency and concentration of the active chemical ‘reserpine’ that the plant produces</p>
</li>
<li>
<p>There are more than 50,000 genetically different strains of rice and 1000 varieties of mango</p>
</li>
</ul>
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<h3 id="successspecies-diversitysuccess"><Success>Species diversity</Success></h3>
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<ul>
<li>Level of biodiversity</li>
</ul>
<ul>
<li>Species Diversity - The diversity at species level within a particular region</li>
</ul>
<p>Example- Western Ghats have greater amphibian diversity than eastern ghats</p>
<ul>
<li>Ecological Diversity - It is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet</li>
</ul>
<p>Example- India with different types of ecosystems such as deserts, forests, hills, mangroves, coral reefs, wetlands, estuaries etc has greater ecosystem diversity than scandinavian countries</p>









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<h3 id="successnumber-of-species-on-earthsuccess"><Success>Number of species on earth</Success></h3>
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<li>
<p>Total number of plant and animal species as per IUCN (2004) - 1.5 million plus</p>
</li>
<li>
<p>We still do not have accurate data as many species are yet to be discovered and described</p>
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<li>
<p>Many estimates are only educated guesses</p>
</li>
<li>
<p>Robert May’s estimate of 7-8 million is somewhat</p>
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<p>scientifically sound estimate</p>
</li>
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<h3 id="successbiodiversity-of-indiasuccess"><Success>Biodiversity of India</Success></h3>
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<p>India is among the 17 mega diverse countries of the world</p>
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<li>
<p>It has only 2.4% of world’s land area and it shares 8.1% of the global species diversity</p>
</li>
<li>
<p>There are about 45,000 species of plants and 90,000 species of animals in India</p>
</li>
<li>
<p>According to May’s estimate. it may go upto 1,00,000 species of plant and 3,00,000 animals
of animals</p>
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</ul>
</li>
</ul>
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<h3 id="successhow-much-of-the-species-are-we-loosingsuccess"><Success>How much of the species are we loosing?</Success></h3>
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<p>How much of the species are we loosing?</p>
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<p>We are witnessing rapid loss of species today This has been estimated to be between 1000 and 10,000 times higher than the natural extinction rates</p>
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<p>If this loss continues at this pace, we could loose all our natural wealth in less than two centuries</p>
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<p>This may be regarded as 6th Extinction Crisis</p>
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<li>
<p>Would we ever be able to complete the inventory of the biological wealth of our country?</p>
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<h3 id="successpatterns-of-biodiversitysuccess"><Success>Patterns of biodiversity</Success></h3>
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<p>Nature’s biological library is burning even before we catalogued the titles of all the books stocked there!</p>
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<li>Patterns of Biodiversity</li>
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<li>
<p>Latitudinal gradients</p>
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<p>In general, species diversity decreases as we move away from the equator towards the poles</p>
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<p>Example- Colombia located near the equator has about 1400 species of birds while New York at 41 degree north Has 105 species and Greenland at 71 degree N has only 56 species</p>
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<h4 id="successtropics-harbour-more-biodiversity-as-compared-to-temperate-regionssuccess"><Success>Tropics harbour more biodiversity as compared to temperate regions!</Success></h4>
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<li>
<p>Temperate regions were subjected to frequent relatively undisturbed for millions of years and thus have along evolutionary time for species diversification</p>
</li>
<li>
<p>Tropical environments are less seasonal, relatively more constant and predictable. Such constant
environment promote niche specialisation and lead to greater species diversity</p>
</li>
<li>
<p>More solar energy contributes to higher productivity which in turn lead to greater diversity</p>
</li>
</ul>
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<h3 id="successimportance-of-species-diversitysuccess"><Success>Importance of species diversity</Success></h3>
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<ul>
<li>Does the number of species in a community really matter to the functioning of the ecosystem?</li>
<li>Many ecologists believe that communities with more species, generally tend to be more stable than those with less species.</li>
<li>What exactly is stability for a biological community?</li>
<li>Features of a stable community</li>
<li>It should not show too much variation in productivity from year to year</li>
<li>It must be either resistant or resilient to occasional disturbances</li>
<li>It must be resistant to invasions by alien species</li>
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<h3 id="successimportance-of-biodiversitysuccess"><Success>Importance of biodiversity</Success></h3>
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<li>
<p>Rich biodiversity is not only essential for the health of an ecosystem but imperative for the very survival of the human race on this planet</p>
</li>
<li>
<p>Now What humans have started understanding this, Biodiversity and its conservation has acquired
international concern the world over</p>
</li>
<li>
<p>At a time when we are losing species at an alarming rate, one might ask- Does it really matter to us if a
few species become extinct?</p>
</li>
<li>
<p>Would Western Ghat ecosystems be less functional if one of its tree frog species is lost forever?</p>
</li>
</ul>
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