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KETAHANAN EKOSISTEM Biodiversitas smno.psdl-ppsub.2013 ECOSYSTEM BIODIVERSITY BIODIVERSITAS 1. Biodiversity = the amount of biological or living diversity per unit area. It includes the concepts of species diversity, genetic diversity and habitat diversity 2. Genetic diversity = the range of genetic material present in a gene pool or population of a species 3. Species diversity = variety among species per unit area. Includes both the number of species present and their abundance. 4. Habitat diversity = The range of different habitats or number of ecological niches per unit area in an ecosystem, community or biome. Conservation of habitat diversity usually leads to conservation of species and genetic diversity Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 BIODIVERSITAS: SPESIES & PROSES • Is key to the overall function of earth • In general Diversity = Stability • Biodiversity is – Nature’s insurance policy against change – The source of all natural capital for human use – The way chemical materials are cycled and purified – The end result of millions of years of evolution and irreplaceable Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 BIODIVERSITAS 1. Richness: The number of species per sample is a measure of richness. The more species present in a sample, the “richer” the sample. 2. Evenness: A measure of the relative abundance of the different species making up the richness of an area. Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Quantifiying this Diversity – Simpson’s Index D = N (N – 1) ∑ n (n – 1) • Where D = diversity index N = total # of organisms of all species n = # of individuals of particular species Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Quantifiying this Diversity – Simpson’s Index • High values of “D” suggests a stable and ancient site • A low value of “D” could suggest pollution, recent colonization, or agricultural management • Index normally used in studies of vegetation but can be applied to comparisons of diversity of any species Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 How does diversity exist? • Natural Selection = survival of the fittest • Fitness = a measure of reproductive success • If all individuals are variable • And populations produce large numbers of offspring without increase in population size • And resources are limited • And traits are heritable • Then those individuals who are best adapted to the environment will survive and pass on their genes • Gradually the gene frequency in the population will represent more of these “fit” individuals Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 SELEKSI ALAMIAH • Environmental Pressures select for some genotypes over others • Alleles resulting in a beneficial trait will become more common • Heritable traits that increase survival chances are called adaptations • There are many niches or habitats and roles available in the environment • As populations adapt they fill new niches and over time may develop into new species Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Speciation • Certain circumstances lead to the production of new species through natural selection • Most common mechanism has 2 phases geographic followed by reproductive isolation 1. Geographic isolation groups of a population of the same species are isolated for long periods – A group may migrate in search of food to an area with different environmental conditions – Populations may be separated by a physical barrier (mountain range, river, road) – Catastrophic change by volcano eruption or earthquake – A few individuals carried away by wind or water to new area Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Speciation 2 2. Reproductive Isolation mutation and natural selection operate independently on the 2 populations to change allele frequencies = divergence • If divergence continues long enough genetic differences may prohibit (1) interbreeding between populations and/or (2) production of viable, fertile offspring • One species has become 2 through divergent evolution • For most species this would take millions of years • Difficult to document & prove this process Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Northern population Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage. Arctic Fox Early fox population Spreads northward Different environmental and conditions lead to different southward selective pressures and evolution and into two different species. separates Southern population Adapted to he through lightwe fur and long ea legs, and nose, w give off more h Gray Fox Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Consequences of Plate Activity • Speciation processes rely on physical separation of organisms • Plate techtonics – can lead to separation of gene pools – mountain ranges form, faults separating land masses – Can link species and land areas e.g. land bridges Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Consequences of Plate Activity II • Plate techtonics generates new habitats – Island chains over hotspots – Hawaii – Mountain habitats – Himalayan mountains – also associated effects on surrounding areas – Hydrothermal vent communities – Changes climate on land masses – continents drift into new climate zones e.g. antarctica was once covered by tropical rainforest now barren polar ice fields Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 1. Succession effects Diversity • Succession – gradual establishment or reestablishment of ecosystems over time • Pioneer species Climax species – Low diversity at first, few species can tolerate harsh conditions (r selected species) – Most diverse in middle of succession, slower growing species start to fill in – Low diversity at the end, climax species often strongest competitors (K selected species) • Diversity is a function of disturbance intermediate disturbance hypothesis Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Lichens and mosses Balsam fir, paper birch, and white spruce climax community Exposed rocks Heath mat Jack pine, black spruce, and aspen Small herbs and shrubs Time Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Species diversity 0 100 Percentage disturbance Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 2. Habitat diversity influences species & genetic diversity • More complex areas (more diverse habitats) often have higher species & genetic diversity • Ex. Tropical rainforest & Coral reef • In both cases, high degree of structural / spatial complexity • Promotes coexistence by niche partitioning & diversification Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Harpy eagle Blue and gold macaw Ocelot Producer to primary consumer Primary to secondary consumer Squirrel monkeys Climbing monstera palm Slaty-tailed trogon Katydid Green tree snake Secondary to higher-level consumer Tree frog All producers and consumers to decomposers Ants Bromeliad Fungi Diunduh dari: Bacteria plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 45 40 Emergent layer Harpy eagle 35 Toco toucan Canopy Height (meters) 30 25 20 Understory Wooly opossum 15 10 Brazilian tapir 5 Black-crowned antpitta 0 Shrub layer Ground Ground layerlayer Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Complex ecosystems with a variety of nutrient & energy pathways provides stability • Energy is key to the function of all ecosystems • Biogeochemical cycles recycle necessary materials through system • More pathways for energy & matter = more stable • Insurance against natural or human changes Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Aktivitas Manusia • Modify succession by adding disturbance • Logging, Grazing, Burning – all prevent natural successional processes • Fragmenting habitats by development • Isolate populations more likely to get diseases, succumb to local disturbances • We simplify ecosystems tall grass prairie converted to wheat farms more vulnerable Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Cleared plots for grazing Highway Cleared plots for agriculture Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Any ecosystem’s capacity to survive change may depend on its diversity, resilience, and inertia Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012 Biodiversitas Agroekosistem