Lecture 9 Biodiversity.ppt

Lecture 9 Biodiversity.ppt - Lecture-9 Biodiversity Course...

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Unformatted text preview: Lecture-9: Biodiversity জজীবববচচিতত Course Instructor: Md Asif Rahman (ASR) Lecturer, Department of Mathematics and Natural Sciences (MNS) University Building 2 (15th Floor) E-mail: [email protected] Biodiversity Biodiversity : Biodiversity refers to the incredible variety of life found in our planet. Biodiversity refers to the • • Number variety and variability of all life forms on earth. These include millions of plants, animals and microorganisms, the genes they contain and the intricate/complex ecosystems of which they are a part. Three kinds of biodiversity – Genetic diversity চজনগত ববচচিতত : different genes জজীন & combinations of genes within populations Species diversity প্রজজাচতর ববচচিতত : describes the number of different kinds of species within individual communities. কককন একটট টনটদষ জকয়গকর community It has three qualities: { Species richness: the total number of species Species evenness: the relative abundance of species Species dominance: the most abundant species Species diversity is influenced by species richness. All else being equal, communities with more species are considered to be more diverse. For example, a community containing 10 species would be more diverse than a community with 5 species. Influence of Evenness of Species Diversity Community A Species Abundance 1 20 2 20 3 20 4 20 5 20 Species diversity is also influenced by the relative abundance of individuals in the species found in a community. Evenness measures the variation in the abundance of individuals per species within a community. Communities with less variation in the relative abundance of species are considered to be more “even” than a community with more variation in relative abundance. Consider the following two communities. All five species in Community A have the same abundance, whereas there is great variation in abundance across the five species in Community B. For this reason, we would consider Community A to be more even. Community B Species Abundance 1 96 2 1 3 1 4 1 5 1 All else being equal, communities with greater evenness are considered to have greater species diversity. Even though species richness of the two communities is equal (species richness = 5 in each community), Community B is less diverse than Community A because most of the individuals in Community B are members of the same species. Measurement of Species Diversity Determining which community has greater species diversity is easy when either species richness or evenness is held constant while the other parameter varies, but often communities will vary in both richness and evenness. Scientists have developed a variety of mathematical equations (or indices) that incorporate both species richness and evenness into a single measure of species diversity (e.g., the Shannon-Wiener Index and Simpson’s Index). Different diversity indices assign different weightings to species richness and evenness, so the so most useful index to choose depends on the circumstances. - Ecological diversity পচরববশগত ববচচিতত : The variety of unique biological জজীবচবজজানসসংকজান communities found on the Earth. It assesses the richness & complexity of a biological community different habitats, niches, species interactions Biological evolution বজব চববতর ন : refer to the change in inheritedউত্তরজাচধিকজার চহিবসবব প্রজাপ characteristics of a population from generation to generation. Processes lead to evolution: Mutation, Natural selection(survival of the fittest) , Migration (টমটটশন.পচরবতচক, পচরবতচক, প্রজাকক চতক চনবর জা চিন , মজাইবগ্রেশন ) How many species are there: – – – Over 100 million Only 1.8 million named Between 150 to 200 species become extinct day! বলল প every Extinction- elimination of a species - - Normal process of natural world In undisturbed ecosystem rate is about one species lost every decade Human impacts have acceleratedএকটসলকরকটটড গচত বক চ দ্ধি পজায that rate causing hundreds or perhaps thousands of species, subspecies & varieties to become extinct every year. Extinction due to Destruction of habitat Expansion of cities Deforestation Pollution Global warming ( 20-30% species are at risk) Introduction of Invasive আকমণকজারজী species. Eucalyptus Example: • • • Habitat: where a species live Ecological Niche: what is does or its profession. Role of certain species played in its ecosystem. Niche includes: – – – – Range of tolerance, like temperature/water availability Resource use: food/nutrition How it interacts with others like search for food Role play in energy and nutrient cycling • Fundamental Niche: Fundamental niche is the natural habitat of a species, where it can easily get food for its energy requirements, and can mate and reproduce without the fear of predators চশকজারজী • Realized Niche: Niche after compromising with other competing species Terms related to Species Habitat �Exotic species:-a species introduced into new geographic area. �Endemic Species:-a species that is native to a particular area and not native elsewhere is called an endemic species. (An endemic species is an animal or plant species whose habitat is restricted to a particular area or space on the globe. ) �For example, Monterey pine is endemic to a portion of the California coast and exotic in New Zealand. �Cosmopolitan species:-a species with a broad distribution, found all over the world wherever the environment is appropriate. �For example, the moose is found in both North America and Europe and is therefore a cosmopolitan. �Ubiquitous Species:-species that are found almost anywhere. �For example, human are ubiquitous as are some bacteria. Interactions between species There are three basic kinds of interactions between species �Competition –in which the outcome is negative for both groups. �Symbiosis –which benefits both participants �Predation-parasitism –in which the outcome benefits one and is detrimental to the others. Environmental factors that influence diversity A. factors that tend to increase diversity A physically diverse habitat Moderate amounts of disturbance (fire or storm) A small variation in environmental condition (temperature, precipitation etc.) High diversity at one trophic level increase the diversity at another trophic level An environment highly modified by life (exp. Rich organic soil) Evolution Environmental factors that influence diversity B. factors that tend to decrease diversity Environmental stress Extreme environments (conditions near to limit of what living things can withstand) A severe limitations in the supply of an essential resources Extreme amount of disturbance Recent introduction of exotic species (species from other area) Geographic isolation চবচচ্ছিন্নতজা. Importance of biodiversity At least 40% of the world’s economy and 80% of the needs of poor are derived from the biological resources. The greater opportunity for medical discoveries, economic development and adaptive response to such new challenges as climate change. The natural environment provides the basic conditions without which humans could not survive. We need to breathe, eat, drink and shelter ourselves and we get all this from the natural world. Ecological importance Trees provide habitat and food for birds, insects, other plants and animals, fungi and micro-organism Birds, insects and other animals serve as pollinatorsপরজাগবহিণকজারজী Parasites and predators act as natural population controls Various organisms, such as earthworms ককক বচিজা and bacteria are responsible for recycling organic materials and maintaining the productivity of the soils Green plants remove carbon dioxide from the atmosphere and replenish it with oxygen. Forests are particularly important “sinks” for the absorption of carbon dioxide and this are the key factors in reducing global climate change. Economical importance Food: species are hunted, fished, gathered, as well as cultivated for agriculture and aquaculture. Fuel: timber and coal are only two examples of natural resources used to produce energy Shelter and cloth: timber and other forest products are used as building materials for shelter. Fibers such as wool and cotton are used to make clothes Medicines: both traditional and processed drugs are obtained from biodiversity Other goods: paper and pencils come from raw materials provided by earth’s diversity Cultural and Aesthetic Plants and animals are often used as symbols, for example in flags, paintings, sculptures, photographs, stamps and legends. Biodiversity is also beautiful; it is a pleasure to see and smell flowers in a field, to listen to birds singing etc. Each and every living being in this earth has some role to play and has the right to exist irrespective of its usefulness to human. Loss of biodiversity: causes and consequences Unplanned development and habitat destruction Changing agricultural and forestry practices Invasion by introduced species Over-exploitation for commercial gain Environmental pollution Global climate change Nature of legal systems Nature of management systems International trade Growing demands Conserving/Preserving biodiversity National conservation strategies Building on indigenous knowledge Community participation in conservation International conservation strategies biodiversity ...
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