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Ecology Study of interactions among organisms…. & between organisms with their environmental factors3-The Biosphere Biosphere • The portion of the Earth that supports life • Composed of two parts: 1. Biotic factors – the living organisms that inhabit an environment • All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection 2. Abiotic factors – the nonliving parts of an organisms environment • Air currents, temperature, light, moisture • Have effect on living things and often determine which species can survive in an area Levels of organization in an organism • Chemicals make up cells… • Which make tissues… • Organs… • Systems… • And finally, the individual organism Levels of organization in ecology • In Ecology, we begin with the individual and move through the levels to the planet, Earth Species • Group of organisms with similar characteristics • Able to breed and produce fertile VIABLE offspring Species Hybrid Populations • Group of individuals (of the same species) that live in the same area • Example? • All the fire ants in a pasture Community • Groups of different populations that live together • Examples? • All the ants, birds, grass, cows, etc a pasture in Ecosystem • Collection of all organisms (biotic) that live in a particular area, together with their non-living (abiotic) parts of an environment • Examples of abiotic factors?? • Climate, soil type, amount of rainfall, etc Southern Pine Ecosystem Fort Bragg, North Carolina Community Ecology • Habitat – a specific place where an organism lives out his life • Niche – the role an organism plays in the environment Symbiotic Relationships – two organisms living in close association with one another 1. Competition (-/-) • compete for limited resource • Food, mate, territory 2. Predation (+/-) – Hunt and kill your prey 3. Parasitism (+/-) 4. Mutualism (+/+) • lichens (algae & fungus) 5. Commensalism (+/0) • barnacles attached to whale Symbiosis – two organisms living in close association with one another Mutualism Commensalism The act of two organisms utilizing one another. Both thrive and help each other. The act of one organism utilizing another living organism. One thrives and the other is neither harmed nor helped Parasitism The act of one organism feeding upon another living organism. The parasite thrives to the host’s detrimentand the host is harmed. Symbiotic Relationships commensalism mutualism +/+ +/0 +/- predation competition -/- Types of Consumers: Herbivores (a.k.a. primary consumers) feed directly on producers Types of Consumers: Carnivores (a.k.a. secondary consumers) feed on other animals Types of Consumers: Omnivores • feed on both plants and animals • can be either primary or secondary consumers, depending on food chain Scavenger • An animal or other organism that feeds on dead organic matter Types of Consumers: • Decomposers/Saprophyte/Detritivores • feed on (and recycle) dead or decaying matter • completing the chain, by returning nutrients needed by producers to the environment Scavengers eat dead things but do not recycle Decomposers feed on dead things AND recycle them Energy flow through the biosphere • Autotrophs (producers) • organisms that make their own food • Heterotrophs (consumers) • Rely on other organisms for their food supply AUTOTROPHS Water + CO2 Sugar + O2 HETEROTROPHS Sugar + O2 water + CO2 What’s the ultimate source of energy for all life? Food chain • Series of steps in which organisms transfer energy by eating and being eaten • Arrow always points the direction of energy flow…..to the consumer Food Chain • The pathway of energy that DECREASES as it passes through the trophic (feeding) levels • Trophic level of an organism is the position it occupies in a food chain Food web • Network of complex interactions, linking all of the food chains together • Show ALL the possible feeding relationships • Many connections throughout ecosystem Ecological Pyramids • Energy Pyramid • Biomass Energy Lost as Heat Pyramid • Numbers Pyramid Hawk-eye Question: Why are all three shaped as a pyramid? What is the relationship between the numbers of producers and Consumers? How does this relate to the energy flow through the ecosystem? pyramid of numbers Energy Pyramid ONLY 10% of energy is passed on to next level So fewer and fewer organisms can be supported at each level Biogeochemical cycles: • Water (hydrologic) cycle • Driven by solar energy • Recycles water, which is primary component of all life • Phosphorus Cycle • driven by decomposing bacteria & fungi • phosphorus is an important component of ATP, Nucleic acids, & phospholipids CO2 in Atmosphere Carbon Cycle • The Carbon Cycle is driven mainly by TWO processes: • Photosynthesis the process by which producers convert sunlight into a useable form of energy CO2 in Ocean • Cellular Respiration overall process by which the body gets and uses oxygen and gets rid of carbon dioxide Nitrogen Cycle • driven by decomposition by nitrifying bacteria and fungi • atmospheric nitrogen must be converted to a usable form that plants can use NITRATE N2 in Atmosphere NH3 NO3 – and NO2 – What form of nitrogen can plants use? • Atmospheric Nitrogen… N2? • Proteins? • Amino Acids? • Ammonia… NH3? • Ammonium… NH4? • Nitrite… NO2? • Nitrate … NO3? Day 2 Ecological Succession IV. Ecological Succession • transition in species composition over time • SLOW process, can take years or decades • usually occurs after a disturbance • Two types: Primary and Secondary Mt. St. Helens 1. Primary Succession • Takes place over land where there are NO living organisms. • Ex. Bare rock, volcano created new island Succession of Species pioneer species lichens & mosses compete well in high sunlight grasses more shade tolerant species shade tolerant species stable community climax forest bushes & small trees trees 2. Secondary Succession • Existing community cleared, but base soil is still intact • Ex. Forest fire, harvesting, hurricane Mt St Helens Vid Clip burning releases nutrients formerly locked up in the tissues of tree the disturbance starts the process of succession over again Bastrop Fire Bastrop Fire Vid of Bastrop Sept 2015 IIV. Species diversity • Greater diversity = greater stability • Greater biodiversity offers: more food resources more habitats more resilience in face of environmental change Populations • members of the same species that reside in the same area Characteristics of populations a. Geographic distribution: Where do they live? b. Density: How many are found in a given unit of area c. Growth rate: How quickly do they grow? Daisy population Factors affecting population growth? 1. Birth rate: number of offspring per time period 2. Death rate: number of deaths per time period 3. Migration rate movement in and out of populations in a period of time • Immigration: in • Emigration: out Exponential growth • Occurs when individuals in a population reproduce at a constant rate • Only under ideal conditions Exponential growth activity • White flies have a 21 day life span • During their life span the female will lay approx. 120 eggs • Calculate the exponential growth of one pair of flies for 6 generations. • For this experiment we will assume that no death occurs Logistic growth • Occurs when a population’s growth rate slows or stops, following a period of exponential (geometric) growth • Carrying capacity: that a given can support largest number environment Click image to play video. Limiting factors • cause population growth to stop • Density-dependent factors depend upon population size: • • • • Competition Predation Parasitism Disease Competition • Occurs when 2 species occupies the same niche & habitat • What are some things they compete for? Competition • Using this 1990 census map of US population densities, what can one deduce at resource competition between the different parts of the country? How can competition explain population size in nonhuman species? Predation • Predator: one that consumes or exploits a particular species for self gain • Prey: one that is consumed or exploited • What would you expect to happen to prey populations if the predator numbers increased or if predator numbers decreased? Figure 5-7 Wolf and Moose Populations on Isle Royale 60 2400 50 2000 40 1600 30 1200 20 800 10 400 0 1955 1960 0 1965 1970 1975 Moose 1980 1985 1990 1995 Wolves Describe the relationship between the wolf and moose populations shown in the graph. Predator-Prey relationships Parasitism and Disease • Both deplete the host organism of vital minerals and nutrients to sustain life. • Death of the organism results in the decline of population size. Heart worms (roundworms) as exposed by a veterinarian Density-independent factors • Limiting factors on population size, regardless of the number of individuals in the population • • • • Weather Natural disaster Seasonal cycles Human activities (habitat destruction) Corals that have died from weather changes, leading to increased water temperature and pollution. Day 3 Historical Human Population Growth Industrial Revolution begins Agriculture begins Plowing and irrigation Bubonic plague It took 500,000 years to reach 1 billion & less than 200 years to reach 5 billion. What might be some reasons why? What’s the carrying capacity for the human population? What if it’s right here? --------------------------- But, what if it’s right here? --------------------------- (We do know it lowers when pollution occurs) Age structure diagrams (population profiles): graphs showing numbers of people in different age groups in the population U.S. Population Males Females Rwandan Population Males Females What conclusions can be drawn from these graphs? Human activities that affect the biosphere • Hunting& Gathering • Agriculture • Industry • Urban development • Austin Smart Growth Initiative Types of resources Nonrenewable resources: • unable to be replenished through natural means • Ex: fossil fuels, natural gas Renewable resources: • able to be replenished but is not unlimited • Ex: freshwater Sustainable development • A way to use natural resources without causing long term environmental problems • This plan takes into consideration environmental, economic, and community demands Problems land resources face Desertification • the process of overusing land and drought leading to the formation of arid, desert lands that cannot sustain agriculture Soil erosion • loss of topsoil layer from over farming (plowing) lands Deforestation • The process of cutting down (logging) forests for lumber and land. • Leads to severe erosion during heavy rains. • Which can lead to permanent changes to local soils and microclimates. Overfishing • Harvesting fish faster than they can be replaced by reproduction. • What happens to aquatic food webs if overfishing continues to occur? Aquaculture • raising water animals for human use • Pictured to the right are tilapia fish farms in Australia that then export the fish to markets. Air pollution • Combustion of carbon fuels released nitrogen and sulfur that combine with water to form acid rain. • Pollutant: • any harmful substance that enters the biosphere from land, air, or water Acid rain Why should we preserve biodiversity? Biodiversity: • sum total of genetically based variety of all organisms in the biosphere • Ecosystem diversity • Species diversity Why should we preserve biodiversity? • Biodiversity is one of Earth’s greatest natural resources. • Species of many kinds have provided us with foods, industrial products, and medicines – including painkillers, antibiotics, heart drugs, antidepressants and anticancer drugs. Threats to species biodiversity • Human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments. Threats to species biodiversity • Endangered: species that is declining in population size • Extinction: species that disappears from all or part of its range Endangered status: Ailuropoda melanoleuca Dodo Bird • The dodo has been extinct since the mid-to-late 17th century. • Its extinction occurred during recorded human history and was directly attributable to human activity Habitat fragmentation • When land is developed through or around ecosystems, the species residing within are impacted in what way? Central Park in New York City is a perfect example of habitat fragmentation. DDT • First synthesized in 1874, DDT's insecticidal properties were not discovered until 1939, and it was used with great success in the second half of World War II to control malaria and typhus among civilians and troops. • After the war, DDT was used as an agricultural insecticide, and soon its production and use skyrocketed • DDT was banned in most countries in 1972 Biomagnification / BioAccumulation : • Increasing the concentration of harmful materials up the food chain Introduced species • Humans transport animal and plant species from one part of the world to another. • Many of these species can become invasive. They reproduce rapidly and lack parasites and predators that helped control their populations “back home.” Nutrias are native to South America but have become pests in coastal US cities. Water Hyacinth Hydrilla Kudzu Fire Ants Conserving Biodiversity • To conserve biodiversity and multi faceted approach is best: • Protection of species • Protection of habitat • Protection of biodiversity Conserving Biodiversity Challenges • Balancing : • Public need and economics • Public policy • Conservation Charting a Course for the Future • Researchers are gathering data to monitor and evaluate the effects of human activities on important systems in the biosphere. • Issues: • Ozone depletion • CO2 emissions • Global warming • Alternative fuels • Alternative food sources Ozone depletion • Ozone: layer of concentrated gas that protects the Earth from harmful UV rays • O3 • 1970s, scientists found a gap in the ozone layer near Antarctica. NASA image Global warming • Compounding the ozone depletion was the buildup of CFCs (chlorofluorocarbons) from aerosols and AC units with Freon. • CFCs trap heat, leading to a rise in the global temperature. Ozone Click on image to play video. Value of a Healthy Biosphere • More complex and diverse ecosystems are the more stable they are. • Complexity + Diversity = Stability • All ecosystems play a role in the health of the biosphere.