Text of Agenda Warm-up Population Growth demo Notes Population Growth worksheet
Agenda Warm-up Population Growth demo Notes Population Growth worksheet
Population Activity What is an infection? Bacteria that invades your body and can also move from person to person
Principles of Population Growth Population A group of organisms, all of the same species, that live in a specific area at the same time. Population growth is defined as an increase in size of a population over time However, populations grow at different rates.
Linear Growth If a population grew at a set amount each year, say by 10 organisms per year, then the population has LINEAR GROWTH However, populations normally do not have linear growth. Linear growth looks like this (Please draw in your notes)
Question Your parents give you two options for allowance 1.1,000 a month 2.A penny on the first day of the month that doubles to two pennies on the second day and so on until the last day of the month Which option do you choose?
Exponential Growth If you graph the allowance we just saw on the graph it will look like this: (Please draw in your notes)
Exponential Growth A population that is growing without any limits, would have exponential growth. Meaning that as the population gets bigger, it also will grow faster But, populations cannot keep exponential growth for very long, because the environment would not be able to support it.
Carrying Capacity The environment has a CARRYING CAPACITY for each population Carrying capacity is the number of organisms that an environment can support. Once a population reaches its capacity, its growth stops.
Question What are some examples of things that can limit growth?
What can limit growth? Limiting factors limit growth Different sizes of populations will also have different factors affecting them. When growth has been limited its graph will look like this:
Density Dependent Factors Density Dependant Factors are factors that have an increasing effect as the population increase, hence will affect larger populations. Examples: Disease, Competition, Parasites, Predators, Food These types of factors spread more quickly in larger populations.
Density Independent Factors Density Independent Factors effect any population, regardless of size. Population size does not matter. Examples: Volcanic eruption, Temperature, Storms, Floods, drought, chemical pesticides
Organism Interactions Limit Population Size Predation Predator consuming prey on a large enough scale can have a drastic effect on the size of prey population and hence predator population Competition Many individuals competing for scarce supplies Density-dependent factor Crowding and Stress Also density dependant. Stress symptoms include aggression, decrease in parental care, decreased fertility, and decreased resistance to disease
Question Do any populations exhibit exponential growth?
Human Population Growth
World Population Census - Taken in the US once every 10 years Demography - Study of human population size 6 Billion in 1999 1.3 Million per year in 2002
Warm-Up Which of the following might be a limiting factor in an organisms survival? A.Abundance of predators B.Temperature and light C.Food availability D.All of the above
Biodiversity loss http://www.youtube.com/watch?v =TP-V4VLLHNE
Human Population Growth Human Population Growth is Different that other organisms because humans consciously change their environment Eradication of diseases Methods for producing more food Technology
Calculating Growth Rate Birthrate - Number of live births per 1000 population in a given year Death rate - Number of deaths per 1000 population in a given year
Immigration vs Emigration Immigration is the movement into a country. Emigration is the movement out of a country. (Birth Rate + Immigration Rate) (Death Rate + Emigration Rate) = Population Growth Rate (PGR)
Age Structures Age Structures tell us how many people are in each age group A younger aged population will grow more rapidly than an older population.
Which age structure diagram has more young people? Why might that be? A B C
Biological Diversity Biodiversity - Variety of species in a specific area
Importance of Biodiversity Interdependence of organisms Life depends on life Stability Many species and diversity allows for better chances of survival Important to people Foods Industrial products Medicines such as painkillers, antibiotics, heart medication, anti-depressants, anti-cancer drugs Depend on other organisms for oxygen, nutrients Clothes, Furniture, Beauty Can you think of any other reasons why biodiversity is important?
Loss of Biodiversity Extinction - Disappearance of a species when the last of its members die Passenger Pigeon (1914) Endangered Species - Numbers become so low that extinction is possible Humpback Whale Threatened Species - Populations decline rapidly and are likely to become endangered Grizzly Bear http://ecos.fws.gov/tess_public/StartTESS.do
Threats to Biodiversity 1.Habitat Loss The largest threat 70s 80s Amazonian rainforest Coral reefs
Threats to Biodiversity 2.Habitat Fragmentation Separation of wilderness areas from other wilderness areas Increased extinction of local species ___________ of ecological processes New opportunities for invasions by introduced or exotic species Increased risk of fire Changes in local climate Smaller fragments mean less biodiversity Geographic isolation leads to genetic isolation Some organisms need large areas for hunting and reproduction
Biotic Effects of Fragmentation Animals that require large areas in which to graze can no longer do so animals starve Likewise large predators can not obtain enough to eat in a small spot - animals starve Migration becomes difficult and species either starve or get wiped out after events such as fire
Abiotic Effects of Fragmentation Climate can change in the areas Think about the temperature in a forest vs. open spaces Edge Effect The different conditions along the boundaries of an ecosystem. as areas become smaller the changes at the edges start to influence the conditions inside.
Threats to Biodiversity 3.Habitat degradation - Damage to a habitat by pollution Types: Air, Water, and Land
I. Air Pollution Importance: can have negative effects on organisms, such as breathing problems, genetic mutations, as well as irritating the eyes & nose. Causes: Volcanic eruptions, forest fires, Chlorofluorocarbons (CFCs), burning fossil fuels is the #1 cause
Problems from Air Pollution Acid Precipitation - Caused by emissions from burning fossil fuels. These emissions combine with water vapor in the air to form rain, snow, sleet and fog with low pH values Leeches nutrients from the soil, kills plants, lowers pH of water supplies, Responsible for killing many trees in US forests Also strongly effects lake ecosystems killing plants, animals & other organisms
Air Pollution Continued Ozone layer depletion - Ozone = O 3, It absorbs some of ultraviolet waves striking atmosphere natural sunscreen CFCs break down ozone CFCs used in refridgerators, air conditioners, some aerosols and used to make polystyrene Spring hole at largest Hole allows more UV rays in which causes increased exposure to UV radiation, this can lead to mutations.
II. Water Pollution Importance: degrades aquatic habitats in streams, rivers, lakes and oceans thereby strongly affecting and even killing aquatic life. Causes: 1. Excess fertilizers, animal wastes from farms can be carried into the water. These nutrients cause algal blooms which can further harm aquatic life by removing needed oxygen from the water. Additionally, silt from eroded soils can clog gills of fish 2.Detergents, heavy metals, chemicals 3. Abandoned drift nets k