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Adapting to a Changing Planet PLANT & ANIMAL ADAPTATIONS/BEHAVIORS Nastic responses - reversible, responsive movements of plants (sunflowers, Venus fly-traps) Tropism – response of a plant to an environmental stimulus (+ & -) Gravitropism – grow towards the force of gravity Phototropism – grow towards light Thigmotropism – response to touch Plant Hormones – stimulates the lengthening of cells, causes apical dominance, (plants grow straight up with little branching) & inhibits fruit dropping Gibberellins – cell elongation, cell division, dwarf plants (lack gibberellins) Ethylene – gas – ripening of fruits Cytokinins – increase rate of growth Abscisic acid – slows growth (used in seed dormancy – washed out when conditions are favorable) Auxin Photoperiodism – response of plants to periods of light & dark Short-day plants – flower in winter, spring, or fall Long-day plants – flower in the summer Intermediate-day plants – equal amts. Of night & day (equatorial plants) Day-neutral plants – flower regardless of the amount of dark/light What adaptations have aquatic plants made? Tissues with air-filled spaces for oxygen to diffuse, roots with air spaces, cypress knees, seeds that float What adaptations have salt-tolerant plants made? Specialized cells that pump salt out of the plant tissues & onto the leaf surfaces to be washed away by rain What adaptations have desert plants have? Extensive roots, reduced leaves, thick stems that store water, photosynthesis at night Why are some plants carnivorous? To obtain nitrogen that they don’t get from their poor soils What are epiphytes? Plants that grow directly on the bodies of other plants – do not harm the plant What type of chemical defenses do plants have? Poisons, insect hormones that disrupt life cycles & the nervous systems of animals Behavior Terms Stimulus – any kind of detectable signal that carries information Response – reaction to a stimulus Innate Behavior – instinct – consist of Fixed Action Patterns (FAPs) Learned Behavior – alterations in behavior that result from experience Habituation – an animal decreases or stops its response to a repetitive stimulus that neither rewards nor harms the animal (Boy who cried Wolf) Classical Conditioning – animal makes mental connection between stimulus and reward or punishment (2 unrelated stimuli) Operant Conditioning – trial-and-error learning (repeated practice) Insight Learning – applying information to a new situation without trial & error (reasoning) Imprinting – learning based on early experience (visual or chemical signals) – cannot be changed once learned Why do birds migrate? To avoid predators & to reach fertile feeding grounds Which animals are social? What are the advantages? Primates, bees, ants, termites, wasps, dogs, wolves, whales, meerkats, etc. Safety, food, protection of young, efficiency How do animals communicate with one another? Visual, sound, touch, or chemical signals or language Humans have the greatest impact on the environment of any living species on Earth. The increase in our population over the last few centuries has seriously & dramatically changed the face of the Earth. 4 Primary Factors that Have Contributed to these Changes: 1)Availability of Clean Water 2)Sanitary Waste Disposal 3)Better Medical Care 4)Increase in Food Production Ecological Footprint An ecological footprint is used to describe the environmental impact of a population. It is the amount of the earth’s surface that’s necessary to supply the needs of, & dispose of the waste of, a particular population. Americans have a 9.7 ha ecological footprint while Indonesians have a 1.1 ha footprint. The Green Revolution The past 50 years have seen a huge increase in world-wide ag productivity known as the Green Revolution. 3 Primary factors have led to this development: 1) Mechanization of Farming 2) Inorganic Fertilizers 3) Pesticide Development Tragedy of the Commons – when humans deplete a renewable resource to which they have free & unmanaged access Renewable resources – resource that can be replenished rapidly – trees, water, soil, wind Nonrenewable resources – resource that exists in fixed amounts & takes hundreds – billions of years to form – metals, fossil fuels Sustainable Living Using resources at a rate that does not deplete them leads to sustainable use. This practice takes in to account economics & ecology principles. What human activities affect the land? Farming, mining, energy extraction, construction, solid & hazardous waste disposal Land Resources Soil is a renewable resource when used properly. Soil mismanagement includes: 1) Salinization - the soil becomes water-logged & dries out with a salt layer on top 2) Overgrazing - too many animals on too little land 3) Erosion - due to poor farming & construction practices Forest Resources Deforestation leads to severe erosion & nutrient removal. Old-growth forests have never been cut & have high biodiversity. Second-growth forests are newer forests with lower biodiversity. Sustainable forestry practices such as alley cropping, windbreaking, & selective cutting help to preserve forestry & crop resources. Hazardous Waste Hazardous wastes are disposed of in 3 main ways: 1) Injection wells - drill a hole in the ground below the water table & inject the waste 2) Surface impoundment - shallow, lined pools - liquid wastes evaporate 3) Landfills - layers of sand, liners, & clay contain the waste in a giant holding facility What human activities affect the water? Farming, fishing, Landscaping, air pollution, sewage, construction, pesticides, thermal pollution Eutrophication – adding nutrients to water – causes excessive algae growth, bacteria overgrowth, death of other organisms Ocean Resources A fishery catches, processes, or sells fish, shellfish, & aquatic animals. About 50% of all fisheries are fully exploited. Methods of exploitation include: 1) Driftnets - dragged through the water - lots of bycatch 2) Long lining - miles-long fishing lines that catch numerous organisms 3) Bottom trawling - scrape the bottom floor with heavy nets Aquaculture (fish farming) is pursued as a method to avoid fishery depletion. What human activities affect the air? Energy production, burning fossil fuels, cigarette smoking, industry, agriculture, using lead-based materials Air Pollution Primary pollutants are released directly into the atmosphere in a toxic form (carbon monoxide). Secondary pollutants are formed by the combination of primary pollutants (acid rain). Pointsource pollution describes a specific location from which pollution is released (a pipe, factory). Non-point pollution comes from a number of sources (oil in streams, methane in the air). What causes ozone depletion? UV light combines with CFC’s & other ODC’s to break O3 (ozone) into O2 & O What causes global warming? When greenhouse gases trap too much heat in the earth’s atmosphere (CO2, methane, nitrous oxides, CFCs, halons, water) What causes acid rain? Acid rain occurs as a result of pollution in the atmosphere - usually when SO2 or nitrogen oxides mix with water. It leaches minerals, increases aluminum in the soil, & damages, paints, rocks, statues, & buildings. Biodiversity – variety of different species in an area Species diversity - the # of different species in the biosphere Genetic diversity - the gene pools available in the biosphere The greater the biodiversity of an area, the greater the stability of an ecosystem. The Importance of Biodiversity Instrumental value (economic & pharmaceutical worth) Ecological value (clean water, clean air, intact ecosystems) Aesthetic value (for its beauty & worth in itself) Threats to Biodiversity Habitat alteration – significantly changing the living environment of a species Habitat fragmentation – breakup of a habitat into smaller pieces – creates edge effects – microecosystems with different abiotic factors Overexploitation – excessive use Pollution Threats to biodiversity Bioaccumulation the accumulation of a toxic substance in one organism Biomagnification the increase in concentration of a toxin in successively higher trophic levels in a food chain Introduced species – species that migrate or are brought to a new area by humans Conservation Strategies of conservation: 1) Identify threatened & endangered species. 2) Identify biodiversity “hot spots.” 3) Emphasize ecosystem rather than species conservation. Methods of Protecting Biodiversity 1) Nature reserves 2) Focus on “hot spots” 3) Create conservation corridors – connect smaller parcels of land 4) Bioremediation – using living organisms (plants, bacteria, fungi) to detoxify pollution 5) Integrated Pest Management – reducing chemicals used on crops