Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapters 3-5 Communities, Population Biology, Biological Diversity & Conservation Big Idea: How much can ecosystems handle before we screw them up permanently? Living in the Community Community – collection of interacting populations Limiting Factors – environmental factors that affect an organism’s ability to survive in its environment Can be living: food availability, predators Can be non-living: temperature, water, sunlight Can affect a population directly or indirectly For instance, food availability will affect a herbivore and the carnivore that eats the herbivore Ranges of Tolerance Tolerance – the ability of an organism to withstand fluctuations in biotic and abiotic environmental factors Each organism has a specific range that it can survive in for a specific factor Ex: catfish can tolerate warm water with little oxygen, while bass or trout cannot Population Organisms Absent Organisms Infrequent Zone of Zone of Physiological Intolerance stress Low Greatest Number of Organisms Pg. 66 of book Organisms Organisms Infrequent Absent Optimum Range Zone of Physiological Zone of Stress Intolerance Range of Tolerance High Succession Let’s say you no longer cut your lawn. What would happen with sufficient water? 1. The grass gets taller; weeds start to grow. The area resembles a meadow. 2. Later, bushes grow, trees appear and different animals enter the area to live. 3. The bushes and trees change the environment; less light reaches the ground. The grass slowly disappears. 4. Thirty years later, the area is a forest. Succession The orderly, natural changes and species replacements that take place in the communities of an ecosystem Primary Succession – the colonization of new sites by communities of organisms Pioneer Species – the first species in an area Ex: Lichen (a combination of fungus and algae) grows readily after a volcanic eruption Lichens break up rock slowly and help soil accumulate Slowly, more things are able to live in the environment Climax Community – mature community that undergoes little or no change Ex: Deciduous forest Secondary Succession The sequence of community changes that takes place after a community is disrupted by natural disasters or human actions Occurs on land that already has soil The pioneer species will be different and the community will climax in a shorter time Example: Yellowstone burned in 1988 Wildflowers came back first, then grasses, ferns and pine seedlings Biome A biome is a large group of ecosystems that share the same type of climax community There are terrestrial biomes (tundra, taiga, desert, grassland, temperate forest, rain forest) There are aquatic biomes (marine, estuaries, freshwater) Review 1. 2. 3. 4. 5. 6. What are the two kinds of limiting factors? What is a range of tolerance? Give an example. What is primary succession? What is secondary succession? What is a biome? What is a pioneer species? Chapter 4 – Population Biology Population Growth – an increase in the size of a population over time All populations start off growing relatively slowly (relative to their capacity to reproduce) If resources are not limited, all populations will grow exponentially (a “J” curve) Exponential Growth 250 200 Number 150 E. coli 100 50 0 1 2 3 4 5 6 7 8 9 10 Time Realistic Population Growth Resources are never unlimited Populations will reach a carrying capacity – the number of organisms of one species that an environment can support Populations follow an S-shaped growth curve Pg. 94 of book Carrying Capacity – if population gets bigger, organisms die Carrying Capacity --------------------------------------------------------------------------------------------------- Beginning Growth Population slowly increases Leveling Off – competition, limited resources slow growth, limiting factors Rapid Growth – exponential growth Fluctuations – birth and death rates fluctuate with competition and resources Patterns of Population Growth Some organisms reach their carrying capacity faster than others Environmental Conditions This is due to their reproductive patterns Ideal ranges In general, organisms that are small and mature rapidly reach carrying capacity faster Organisms that are large and mature slowly, reach a carrying capacity slower Environmental Limits to Population Growth Density-Dependent Limiting Factors have an increasing effect as the population increases Ex: disease, competition, parasites, food Ex: How does predation effect population sizes? Density-Independent Limiting Factors affect all populations, regardless of their density Most are abiotic factors such as temperature, storms, flood, drought, habitat destruction Density-Dependent Limiting Factors Competition – increases within species as population gets too big. Over food, water, territory, mates, etc. Can you see this in a human population? Density-Dependent Limiting Factors Crowding & Stress – as populations increase in size, individual animals begin to exhibit: Aggression Decrease in parental care Decreased fertility Decreased resistance to disease Can you see this in a human population? Review 1. 2. 3. 4. 5. 6. What conditions must be met for exponential growth? What pattern do populations follow in reality? What determines how fast a population reaches its carrying capacity? Give 3 density-independent limiting factors. How can crowding and stress limit a population? Describe the relationship between predators and prey. Demographic Trends Demography – the study of human population growth characteristics Humans reduce negative environmental effects on our population i.e., growth rate, age structure, geographic distribution i.e., eliminating competitors, increasing food production, controlling diseases Human Population (see pg. 100 in book) 1 A.D. – around 1850 : slow growth After 1850-present: exponential growth (J-curve) Realistic Population Growth Where are humans on this curve? What will eventually have to happen? Pg. 94 of book Carrying Capacity – if population gets bigger, organisms die Carrying Capacity --------------------------------------------------------------------------------------------------- Beginning Growth Population slowly increases Leveling Off – competition, limited resources slow growth Rapid Growth – exponential growth Fluctuations – birth and death rates fluctuate with competition and resources Birth and Death Rates Death Rate – the number of deaths per 1000 people in a given year Affected by life expectancy, diseases in area, stress, etc. Difference in Africa and U.S.? Birth Rate – the number of live births per 1000 people people in a given year. Fertility rate is a large influence here Difference in Africa and U.S.? Birthrate (per 1000) Death Rate (per 1000) Fertility (per woman) Population Increase (percent) Jordan 38.8 5.5 3.3 3.3 Uganda 50.8 21.8 7.1 2.9 Zimbabwe 34.3 9.4 5.2 2.5 Germany 9.4 10.8 1.2 -1.5 Italy 9.4 9.7 1.2 -0.5 Sweden 10.8 10.6 1.5 0.1 Mexico 27.0 5.2 3.1 2.2 United States 14.8 8.8 2.0 0.6 Population Growth Rate (PGR) Immigration – movement of individuals into a population Emigration – movement from a population Population Growth Rate = (Birthrate + Immigration Rate) - (Death Rate + Emigration Rate) Or, for convenience PGR = Birthrate - Death rate When birthrate equals death rate, the population isn’t growing As long as the PGR is positive, the population will continue to grow Doubling Time & Age Structure Doubling Time - the time needed for a population to double in size Age structure refers to the proportions of a population that are at different age levels Doubling Time (in years) = 70/annual percent growth rate What is happening to the world doubling time? If a population has many young members, it will mostly likely grow rapidly If a population has equal numbers of ages, it is stable Look page 103 in book These demographics do not influence world population, but do show movement from or to urban areas, countries, etc. Ecology and Growth Population needs differ throughout the world Some populations have competition for food, water, etc. Some population are more concerned about the health of their citizens When populations grow rapidly, there is often competition for resources Lead to stress, contamination, etc. that lead to disease and affect stability of populations Review 1. 2. 3. 4. 5. How do humans “change the rules” in demography? How do birth rates and death rates influence population growth? How do you calculate population growth rate? What is a population’s doubling time? How do population needs differ around the world? Biological Diversity Biodiversity refers to the variety of life in an area Most common measure is the number of species that live in a certain area Terrestrial biodiversity tends to increase as you move towards the equator (or in isolated warm regions) 2/3 of all land species on Earth are in tropical regions The size of the area also affects biodiversity Larger areas tend to be more diverse (unless other things prevent or encourage life) Importance of Biodiversity Organisms are adapted to live together in a community Biodiversity brings stability to an ecosystem If you take one away, there are consequences to the rest More resources, interactions, etc. When a population utilizes more than one resource, it will be ok if one of them disappear Biodiversity is important to humans Oxygen to breath, remove CO2 Diverse diet / Better crops (resistance) Building materials Possible pharmaceuticals Loss of Biodiversity Extinction – the disappearance of a species when the last of its members dies Threatened Species – when the population of a species begins declining rapidly Since 1980, almost 40 species of plants and animals have gone extinct in the U.S. Can be natural or human-caused In the US: sea otters, loggerhead turtles, bald eagle Endangered Species – population numbers so low that extinction is possible In the US: California Condor, Florida manatees Threats to Biodiversity Habitat loss – the biggest threat Take away resources for life Habitat fragmentation – separation of wilderness areas from other wilderness areas Roads – leads to less biodiversity Animals that migrate or need large areas to hunt Climates can change (take away shade) Edge Effect – the different conditions along the boundaries of an ecosystem Threats to Biodiversity Habitat Degradation – the damage to a habitat by pollution Air, Water, or Land Air Pollution Burning fossil fuels is the greatest source of air pollution Acid Precipitation – sulfur dioxide from burning coal and nitrogen oxides from automobile exhausts combine with water vapor Leaches nutrients from the soil Damages plant tissues Alters pH of lakes Ozone layer damage – CFC’s break down 03 Increased skin cancers Possible cause for amphibian population decreasing Threats to Biodiversity Water Pollution Fertilizers and animal wastes carried by runoff Causes algal blooms These algae die, decay and remove oxygen from the water Silt from erosion clogs gills, blocks sunlight Detergents, metals, industrial chemicals from runoff Debris in oceans and lakes Threats to Biodiversity Land pollution Trash – the average American produces about 1.8 kg of solid waste daily – 657 kg/yr Destroy habitats and pollute areas Pesticides, etc. can also lead to habitat degredation DDT Threats to Biodiversity Introduction of Exotics Exotic species – organisms that are not native to a particular area Can grow at an exponential rate due to a lack of competitors and a lack of predators Take over niches of native species or replace the species Sea lamprey in Great Lakes after Erie Canal Goats on Santa Catalina Island Section 1 Review What are two reasons for a species to become threatened or endangered? Explain how land that gets broken up can contribute to loss of species diversity. What is an edge effect? Explain how changes in an ecosystem’s edges can affect organisms. How can exotic species affect populations of native species? Conservation Biology Conservation Biology is the study and implementation of methods to protect biodiversity. Natural resource conservation natural resources are those parts of the environment that are useful or necessary for living organisms. Species conservation protecting species from extinction and preserving biodiversity Legal Protection of Species 1973, the U.S. Endangered Species Act made it illegal to harm any species on the endangered or threatened list Illegal for federal agencies to fund any project that would harm these species The Convention on International Trade in Endangered Species (CITES) Established lists of species for which international trade is prohibited or controlled Honored by 120 countries Preserving Habitats One way is to create national parks First one in US was Yellowstone Originally this was to preserve the geology Protects natural environments and provides habitats for many organisms Habitat Corridors Protected strips of land that allow the migration of organisms from one wilderness to another Isolated populations inbreed too much Sustainable Use In National Parks, the land is managed This philosophy strives to enable people to use natural resources in ways that will benefit them and maintain the ecosystem Some grazing Harvest fruits Hiking, camping, etc. Preservation Programs Captive Breeding followed by Reintroduction Programs Release organisms into area where the species once lived Ex: black-footed ferret Ex: brown pelican after DDT Seed banks for threatened and endangered plant species Section 2 Review Describe the U.S. Endangered Species Act. Why is it difficult to reintroduce species that have been captive bred? What is sustainable use and how does it influence Utah?