Environmental Sciences: Abiotic Components, Biomes, and Biodiversity - Prof. Edgar Moctezu, Exams of Plant Taxonomy and Evolution

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Lecture 21: Ecology Populations – are all the members of a single species living together Habitats – the location where the population is found (the address of an organism) Niche – the functional role an organism plays in the ecosystem – it encompasses habitat plus relationships with either organism in the ecosystem Community dominant species – the most influential species in the community control the structure and species composition of the community through  Physical factors o Light (provide shade) o Wind (Wind screen) o Humidity (higher than in open areas)  Chemical Factors o Nutirents o PH Biotic - organism that live in a community and interact in food chains  Producers (photosynthesis) – 1st order consumers (herbivores) – 2nd order of consumers (Carnivores)  Each step in the food chain is called a tropic level energy is lost (80 – 95%) Abiotic – non-living components of the environment: climate, light, soil, inorganic, substances  Carbon Cycle –co2 enters the plants through photosynthesis carbon is released back into the air through respiration or fuel  Water Cycle – want enters the atmosphere through vapor and transpiration of plants  Nitrogen Cycle – legumes bring nitrogen into the soil  Phosphorus Cycle Ecosystem Food web – more realistic multiple interactions between several food chains Climax Community – relatively stable community at the end of the succession 1. In equilibrium with the environment 2. Permanent (until major change) 3. Varies depending on conditions Primary Succession – plants become established on land that was completely devoid of soil and vegetation (New volcanic island)  Lichens – mosses- grasses – shrubs - trees Secondary Succession – natural forces or human intervention destroyed the existing vegetation (fire, flooding, logging, agriculture)  Takes place 5-10 faster than primary o Factors : weather, temperature, humidity Soil Characteristics  Soil texture – all soils contain 3 kinds of particles – sand, silt, and clay  Clay – most important: it holds nutrients for plants  Organic Matter – humus is decomposing organic matter in soild  Soil pH – acid (low pH) or basic (High pH) soil influences soil fertility and nutrient availability  Best soil is neutral or slightly acidic pH Lecture 22: Terrestrial Biomes  Biomes: large distinct ecosystems, climax communities for huge regions of the land  Recognized and defined by distinctive vegetation and animal life  Seasons are determined by the tilt of the Earth Biome Location Climate Soil Plant Adaptation Human interaction Tundra (land without trees) Northernmost land biome  Freezing Temperatures can occur every day rarely above 15 C  Little precipitation Wet, shallow permafrost Only top thaws Mostly perennials Many Shrubs and herbs lichens , mosses Short growing season Antifreeze sap, hairy leaves to retain heat Sensitive to human disruption takes a long time to recover (slow growth) Boreal Forest (Taiga) Northern 17% of earths land Near arctic circle Alaska, great lakes Sever winters extreme cold Little precipitation Wet deep permafrost; nutrient poor Soil may be acidic do to decomposing needles Trees dominate especially Pines (conifers) Ground covered of lichens and mosses Hunting leading to extinction Mineral exploitation and lumbering Temperate Deciduous forest Eastern North America Higher precipitation Longer growing season Extreme temperature - 40 – 110 F More acidic and fertile Lower layer deep and rich in clay, topsoil is rich in decayed organic matter (humus) Deciduous = leaves fall off seasonally. Help them survive for snowfall Grasses and wildflowers during the growing season No undisturbed temperate deciduous forests left, due to extensive logging Soil erosion make it difficult for native plants to re- populate Grasslands Widely scattered throughout the US Prairie, Great Plains Low rainfall Warm summers and cool winters Fires major factor in maintaining the biomes Generally fertile deep and rich Wind pollinated Rhizomes to spread at Adapted to fires and drought Used for farmland – food cereals Overgrazed by cattle Urbanizatio n Exotic o Concerns  Destruction of SAV – due to pollutants and soil in rivers  SAV don’t get enough sun light because of: sediment on surface, algae bloom, epiphytic growth on surface  Blue Crab and oyster are declining Lecture 24: Biodiversity, Extinction and the Atmosphere • Rivet Popper: each species is important in their own small way. Lose one little happens lose a lot whole ecosystem fails • Redundancy: Most species are superfluous even with a few ecosystem still goes • Threats to Biodiversity o HUMANS – major cause to species loss o Naturally occurring – • Extinction o Each species has a finite lifetime 99% of all organisms o Background: continuous low level rate of species loss o Mass extinction: large loss of species in brief geological period of time o Causes: climate changes ( Sudden, gradual)  Dramatic flooding, volcanic activity, tectonic shifts  Human activities – single largest cause  Meteorites • Atmosphere o Composed of Nitrogen ( 78%) Oxygen (21%) Argon (.9%) Carbon dioxide (.03%) o Troposphere – closes to earth weather occurs here o Stratosphere – Jets fly ozone layer temperature increases with altitude o Mesosphere – the coldest temperature o Thermosphere – hottest layer due from heat from solar radiation o Acid rain: caused by burning fossil fuel form sulfuric and nitric acids | changes the pH level of soil and water o Green House effect – when carbon dioxide and other greenhouse gases are released into atmosphere from human activities| traps ultra-violent light heat is trapped | to much CO2 o Global Warming due to much CO2 Why is CO2 increasing: burning fossil fuel and deforestation o Solutions – developed nations must cut back on emissions planting more trees alternative energy Kyoto Protocol - Industrialized nations must cut emissions of six greenhouse gases by 7% by 2012 o Ozone Depletion due to CFC (Chlorofluorocarbons) in aerosol cans, coolants, halons, chlorine  Good in stratosphere – shields the earth from UV light it reflects it  Bad in troposphere Lecture 25: Environmental Impact of Agriculture and World Food Issues Impact of Agriculture • Declining biodiversity o Out of 30,000 edible plants only 22 are major source of food o Wild pop. Have greater genetic diversity • Soil Erosion o Loss of soil from tilling the land o Topsoil is loss which contains the nutrients o Solutions: less plowing, more perennials, crop rotation, green manure crops, shelterbelts, strip intercropping, contour cropping • Salinization o Irrigation salt builds up, freshwater contains salt. Salt accumulates plants can’t absorb water o Solutions: new trickle irrigation system delivers water directly to the roots, laser level of fields prevent soggy areas. Restoration of salt-damage land by adding excess water • Desertification o 40% of world’s surface is arid o Expansion of the desert at the expense of cropland or rangeland o Due to natural process and human activity  Overgrazing, cultivating crops, improper irrigation, deforestation o Solutions: replanting with drought – tolerant plants, retire land 10-20 years • Chemical Fertilizers o Excess use of commercial fertilizers – depletes soil of essential minerals, decreases organic matter o Pollution in water = overgrowth of algae. Damage aquatic ecosystem o Solutions: using organic fertilizers, crop rotation with leguminous which provide nitrogen fixation in soil, water treatment to remove nitrate runoff • Pesticides o Consumers demand unblemished fruit and vegetables o Insects developing resistance to pesticides – leads to more toxic pesticides o Untested for health effects may cause cancer or birth defects o Disrupts the food chain o Solutions: biological – using living organism to eat pest insect. IPM integrated pest management World food problems  Solutions: Raising the standards of living in developing countries o Lower birthrates naturally following higher living standards o First step is providing education, adequate nutrition, proper health,  Improve existing crops o Develop and improving native crops – better adapted to specific climactic conditions o Developing new food crops o Quinoa – very high in protein as well as calcium and phosphorus minerals. Adapted to cold and high altitudes. Can be boiled and eaten like rice. o Winged bean – from Asia, all parts of plants are edible are highly nutritious o Amaranth – leaves and seeds can be eaten. High protein made into breakfast cereals, pasta, bread. Popular food in ancient Mexico. Was used in Aztecs religious rituals was banned by Spaniards Lecture 26: Plant Biotechnology Traditional Plant Breeding Improving plants is called selective breeding 1. 1.Selective desired characteristics of crops high yield 2. Hybridization - mating the plants selectively to bring the genes together 3. Offspring is hybrid with combined desired genes 4. Farmers save the seeds from the best plants to grow the next years Green Revolution Genetic Engineering  Transfer of specific genes between organisms using technique of molecular biology  GM Plant: a plant produced through genetic engineering and containing genes from another organism Technique for making GE crops  Restriction Enzymes cut a gene of interest cut a plasmid both with the same restriction enzymes. Glue them together = Recombinant DNA Steps for making a transgenic Plant 1. Identify & Isolate a useful Gene 2. Using Restrictions Enzymes, cut and insert gene into plasmid, plus a marker 3. Vector – transport the gene into the cell with either: a. Agrobacterium b. Gene Gun 4. Select transformed cells containing markers (usually antibiotic resistance) 5. Grows transgenic cells in agar culture – grow transgenic plant Plasmids – small circular pieces of DNA in bacteria Restriction enzymes – cut DNA in a specific region Certain bacteria can infect plants and insert their plasmids into plant cells with their DNA Applications of biotechnology/GE • Examples of GE crops o Hawaiian Papaya – resistant to ring virus o BT corn  Corn that has insecticide protein from bacteria kills corn borer o Ripening control tomato  In tomatoes make an antisense transformation that will suppress the gene for ethylene hormone production. Also modulating cell wall genes to control firmness in ripe tomato fruit o Golden rice  Enhanced nutritional value synthesize Vitamin A  Can prevent blindness in developing countries • Edible vaccines etc o Banana oral vacines for certain diseases an be produced also insulin • Risk vs. benefits of GE crops