Biodiversity and Conservation PDF

Okay, here is the converted text from the images, formatted into a markdown structure. I will focus on transcribing the text, retaining important facts and figures, and using appropriate markdown elements like headings, lists, and tables. # CHAPTER 15 # BIODIVERSITY AND CONSERVATION **15.1 Biodive...

Okay, here is the converted text from the images, formatted into a markdown structure. I will focus on transcribing the text, retaining important facts and figures, and using appropriate markdown elements like headings, lists, and tables. # CHAPTER 15 # BIODIVERSITY AND CONSERVATION **15.1 Biodiversity** **15.2 Biodiversity Conservation** * Biodiversity exists not only at the species level but at all levels ranging from macromolecules within cells to biomes. If an alien from a distant galaxy were to visit our planet Earth, the first thing that would amaze and baffle him would most probably be the enormous diversity of life that he would encounter. Even for humans, the rich variety of living organisms with which they share this planet never ceases to astonish and fascinate us. The common man would find it hard to believe that there are more than 20,000 species of ants, 300,000 species of beetles, 28,000 species of fishes, and nearly 20,000 species of orchids. Ecologists and evolutionary biologists have been trying to understand the significance of such diversity by asking important questions- why are there so many species? Did such great diversity exist throughout Earth's history? How did this diversification come about? How and why is this diversity important to the biosphere? Would it function any differently if the diversity was much less? How do humans benefit from the diversity of life? ## 15.1 BIODIVERSITY In our biosphere immense diversity (or heterogeneity) exists not only at the species level but at all levels of biological organization ranging from macromolecules within cells to biomes. Biodiversity is the term popularized by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organization. The most important of them are: (i) **Genetic diversity:** A single species might show high diversity at the genetic level over its distributional range. The genetic variation shown by the medicinal plant *Rauwolfia vomitoria* growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces. India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango. (ii) **Species diversity:** The diversity at the species level, for example ,the Western Ghats have a greater amphibian species diversity than the Eastern Ghats. (iii) **Ecological diversity:** At the Ecosystem level, India for instance with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater Eco-system diversity than a Scandinavian country like Norway. It has taken millions of years of evolution to accumulate this rich diversity in nature, but we could lose all that wealth in less than two centuries if the present rates of species losses continue. Biodiversity and its conservation are now vital environmental issues of international concern as more and more people around the world begin to realize the critical importance of biodiversity for our survival and well-being on this planet. ### 15.1.1 How Many Species are there on Earth and How Many in India? Since there are published records of all the species discovered and named, we know how many species in all have been recorded so far, but it is not easy to answer the question of how many species there are on earth. According to the IUCN (2004), the total number of plant and animal species described so far is slightly more than 1.5 million, but we have no clear idea of how many species are yet to be discovered and described. Estimates vary widely and many of them are only educated gusses. For many taxonomic groups, species inventories are more complete in temporary than in tropical countries. Considering that an overwhelmingly large proportion of the species waiting to be discovered are in the tropics, biologists make a statistical comparison of the temperate-tropical species richness of an exhaustively studied group of insects and extrapolate this ratio to other groups of animals and plants to come up with a gross estimate of the total number of species on earth. Some extreme estimates range from 20 to 50 million, but a more conservative and scientifically sound estimate made by Robert May places the global specific diversity at about 7 million. *India and biodiversity* * India's land area of the world = 2.4% * India's species diversity = 8.1% * What this means: India is among the 12 mega-diverse countries. * In India, Discovered * Plant Species = 45,000 * Animal Species = Twice the plant species count Let us look at some interesting aspects about Earth's biodiversity based on the currently available species inventories. More than 70% of all the species recorded are animal and plants ( including Algae fungi bryophytes gymnosperms + angiosperms) compromise. No more than 22% of the Total. Among animals Insects are the most special rich taxonomic groups making up more than 70% of the Total that means out of every 10 animals on this planet 7 are insects. Again. How do we explain this enormous diversification of insects? The number of fungi species in the world is more than the combined total of the species of Fishes amphibians reptiles and mammals. In Figure 15.1 biodiversity is depicted showing species number of major taxa. *(It is difficult to accurately describe the pie charts, but here is a list of what they represent)* * **Invertebrates:** Other animal groups, crustaceans, mollusks, insects * **Vertebrates:** Fish mammals, birds, reptiles amphibians * **Plants** Fungi, mosses and allies, Algae, Lichens, and Angiosperms It should be noted that these estimates do not give any figures for prokaryotes. Biologist are not sure about how many prokaryotic specifies there might be. The problem is that conventional taxonomic methods are not suitable for identifying microbial species and many species are simply not culturable under laboratory conditions , if we accept Bio chemical or molecular criteria for delineating species for this group, then their diversity alone might run into millions. **15.1.2 Patterns of Biodiversity** (i) **Latitudinal gradients:** The diversity of plants and animals is not uniform throughout the world but shows a rather uneven distribution. For many groups of animals or plants, there are interesting patterns in diversity, the most well-known being the latitudinal gradient in diversity. In general, species diversity decreases as we move away from the equator towards the poles. With very few exceptions, tropics (latitudinal range of 23.5° N to 23.5° S) harbor more species than temperate or polar areas. Colombia located near the equator has nearly 1,400 species of birds, while New York at 41° N has 105 species and Greenland at 71° N only 56 species. India, with much of its land area in the tropical latitudes, has more than 1,200 species of birds. A forest in a tropical region like Ecuador has up to 10 times as many species of vascular plants as a forest of equal area in a temperate region like the Midwest of the USA. The largely tropical Amazonian rain forest in South America has the greatest biodiversity on earth– it is home to more than 40,000 specifies of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of reptiles and of more than 1,25,000 invertebrates. Scientists estimate that in these rain forests there might be at least 2 million insect species waiting to be discovered and named. What is so special about tropics that might account for their greater biological diversity? Ecologists and evolutionary biologists have proposed various hypotheses; some important ones are (a) speciation is generally a function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification, (b) Tropical environment unlike temperate ones are less seasonal relatively more constant and predictable. Such constants environment promote niche specialisation and lead to greater species diversity and (c) There is moral solar energy available in the tropics, with contributes to hire productivity this inturn might contributes directory to greater diversity. (ii) **Species-Area relationships:** During his pioneering and extensive explorations in the wilderness of South American jungles, the great German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit. In fact, the relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola. On a logarithmic scale, the relationship is a straight line described by the equation: $log S = log C + Z log A$ where: $S =$ Species richness $A =$ Area $Z =$ slope of the line $C = $Y-intercept Ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2, regardless of the taxonomic group or the region (whether it is the plants in Britain, birds in California, or mollusks in New York state, the slopes of the regression line amazingly similar). But, if you analyze the species-area relationships among very large areas like the entire continents, you will find that the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2). For example, for frugivorous (fruit-eating) birds and mammals in the tropical forest of different continents, the slope is found to be 1.15. What do deeper slopes mean in the context? **15.1.3 The importance of Species Diversity to the Ecosystem** Does the number of species in a community really matter to the functioning of the ecosystem? This is a question for which ecologists have not been able to give a definitive answer. For many decades, ecologists believed that communities with most species generally tend to be more stable than those with less species. What exactly is stability for a biological community? A stable community should not show too much variation in productivity from year to year; it must be either resistant or resilient to occasional disturbances (natural or man-made), and it must also be resistant to invasions by alien species. We don't know how these attributes are linked to species richness in a community, but David Tilman's long-term ecosystem experiments using outdoor plots provide some tentative answers. Tilman found that plots with more species showed less year-to-year variation in total biomass. He also showed that in his experiments, increased diversity contributed to the higher productivity. Although, we may not understand completely how species richness contributes to the well-being of an ecosystem, we know enough to realize that reach biodiversity is not only essential for ecosystem health but imperative for the very survival of the human race on this planet. At a time when we are losing species at an alarming pace, one might ask- Does it really matter to us if a few species become extinct? Would Western Ghats ecosystems be less functional if one of its tree frog species is lost forever? How is our quality of life affected if, say, instead of 20,000 we have only 15,000 species of ants on Earth? There are no direct answers to such naive questions but we can develop a proper perspective through an analogy (the 'rivet popper hypothesis') used by stand for the ecologist paul,erilich. In an airplane (ecosystem) all parts are joined together using thoughts of Revers (species). If every passenger traveling in its starts popping a rivet to take home (causing a species to become extinct), it may not affect Flight safety ( proper functioning of the ecosystem) initially, but as more and more Revers are removed, the plane becomes dangerously weak over a period of time Furthermore, which river is removed maybe also critical loss of Revers *or* the wings( key species that driver major ecosystem junctions) is obviously a more serious threat to fight safety than loss of a few rivers *or* the seats or windows inside the plane **15.1.4 Loss of Biodiversity** While it is doubtful if any new species are being added (through speciation) into the earth treasury of species, there is no doubt about they're continuing losses of biodiversity as well as planet has been declining rapidly and I accuse and finger is clearly pointing to human activities. The colonization of tropical specific Islands by humans is said to have led to the extinction of more than 2000 species of native birds. The IUCN Red List (2004) documents the extinction of 784 species (including 338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years . Some examples of recent extinctions include the dodo, quagga, thy laying, Steller's Sea Cow and three subspecies. The last 20 years alone have witnesses the disappearance of 27 species careful analysis or records have witnessed if the disappearance of 27 species. Extinctions are not non-random. (Some are more vulnerable than others) Present % of organism facing extinction: 1) 12% of bird species 2) 23% of mammals 3) 32% of amphibians 4) 31% of gymnosperms Thus amphibians are more vulnerable to extinction. Origin of life on Earth then had been 5 mass extinction extent. Present- 6th mass extent is going This a 100x -1,000x faster than pre human extinction. At this right half of all species well wipe out in next 100 year Shows that extinctions across taxa are not random; some groups like amphibians appear to be more vulnerable to extinction. Adding to the grim scenario of extinctions is the fact that more than 15,500 species worldwide are facing the threat of extinction. Presently, 12% of all bird species, 23 % of all mammal species, 32 % of all amphibian species and 31 percent of all gymnosperm species in the world face the threat of extinction. From a study of the history of life on Earth through fossil records, we learn that large-scale loss of species like the one we are currently witnessing have also happened earlier even before humans appeared on the scene. During the long period (> 3 billion years) since the origin and diversification of life on Earth there were five episodes of mass extinction of species. How is the Six Extinction presently in progress different from the previous episodes? The difference is in the rates: the current species extinction rates are estimated to be 100 – 1,000 times faster than the pre-human times and our activities are responsible for their faster rates. Ecologists won that if the present trends continues nearly half of all the species on the earth might be wiped out within the next 100 years. In general, the loss of biodiversity in a region may lead to (a) decline in plant production(b) lowered resistance to environmental perturbations (such as drought causes are accelerated rates of species extinctions that the world is facing now and largely due to human activities are for major which are evil in our habitat less and fragmentation this is the most important habitat loss from tropical rain forest Tropical rainforest cover initially 14% now 6% Amazon rainforest (lungs of plants) is cut for cultivating soyabean or conversion for concession true grassland to rouse beef cattle **Causes of biodiversity losses:** The accelerated rates of species extinction that the world is facing now are largely due to human activities. There are four major causes (The Evil Quartet is the sobriquet used to describe them). (i) **Habitat loss and fragmentation:** This is most important cause during animals and plants to extinction. The most dramatic examples of the habitat loss and competition forest once covering more than 14% of the most of the earth's and surface they for us now cover no more than 6% percent. (ii) **Over-exploitation:** Humans have always depended on their natural need is turned into greed which lead to overexploitation of natural recourses *Over exploitation of natural recourse Many species in the last 500 years. Stiller sea cow passenger pigeon all with to overexploitation in the Currently the marine fish populating. Are there many ways to overharvest endangering the What are unique alien species When alien species are in reduced International Steller's sea cow and passenger pigeon got extent to to overexploitation. The need of our to Nile Purch in Introduced into last and let eventually The Extents and ecology you in assembling over More than 200 🗣️ of this Species can cause you and must be from their with the The environmental need is **15.2 BIODIVERSITY CONSERVATION** 15.2.1 Why Should We Conserve Biodiversity? narrow utilitarian arguments for biodiversity Human direct economic benefits as food firewood industrial Products 15.2.2 How do we conserve Biodiversity when when When we Conserve the protector whole ecosystem *it’s* biodiversity at all levels is the protector be safe the entire forest to save what the tiger approach is called in said to conservation however animal ( or plant it and danger and threatened organism facing a very