POPULATION ECOLOGY. Population Density. is a measurement of population per unit area. Population Total land area. What is this population density per these unit areas?. 10 m. 1nm. What affects population growth?. 1. Number of births. 2. Number of deaths.
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Population Density • is a measurement of population per unit area Population Total land area
What affects population growth? • 1. Number of births. • 2. Number of deaths. • 3. Number of individuals that enter or leave the population.
Exponential GrowthJ curve • Exponential Growth animation
Conditions for Exponential Growth • 1. plenty of food • 2. plenty of space • 3. protected from predators and disease
Exponential Growth Videos • TeacherTube Videos - Bacterial Growth • **BBC - Learning Zone Class Clips - Bacterial growth – Biology Bacteria Growth Video
Bacterial Culture • (click on animation of bacterial culture) • Bacterial Culture
If the environment is optimum, the two daughter cells may divide into four in 20 minutes. Oh my! 1, 2, 4, 8, 16, 32, 64... Then why isn't the earth covered with bacteria?
Logistic GrowthS curveLogistic Growth (ani) • At first the population increases, then resources become limited…growth at a slower rate.
Carrying Capacity • Largest number of individuals that an environment can support.
INTERPRETING ECOLOGICAL DATA • Graph 1: Rabbits Over Time
INTERPRETING ECOLOGICAL DATA • Graph 2: Average Toe Length • a. In 1800, about how many people surveyed had a 3 cm toe? ~58 • How many in 2000? ~10b. The data shows the *Stabilizing selection has occurred?c. In 2000, what is the average toe length? ~4.5 • What is the average toe length in 1800?about the same, broader range • #see next slide
INTERPRETING ECOLOGICAL DATA • Graph 3: Mexico and US • a. In Mexico, what percentage of the population is between 0-4 years of age? 16 In the US? 7 • b. Which population is growing the fastest? Mexico • c. Which age group has the smallest number in both countries? 80+
INTERPRETING ECOLOGICAL DATA • Chart 4: Trapping Geese • ecologists marked 10 geese • a. Use the formula to calculate the estimated number of geese in the area studied? 60(10) / 6 = 100b. This technique is called Mark & Recapturec. Supposing more of the geese found in the trap had the mark, would the estimated number of geese in the area be greater or lesser? less (bottom number would be greater in formula)
Trapping Geese recaptured
INTERPRETING ECOLOGICAL DATA • Chart 5: Mushroom Plots • She plots a 10 x 10 area and randomly chooses 5 spots, • a.Calculate the number of mushrooms in the forest based on the grid data: Average per grid = 3, 100 plots; total = 300 • b. This technique is called Random Sampling
Snake and Mice Populations The maximum number of individuals a habitat can support is called the Carrying Capacity. Population Growth = Mice Born – Mice Death
INTERPRETING ECOLOGICAL DATA • Chart 6: Snakes & Mice (see next slide) • a. During which year was the mouse population at zero population growth? 2000, closest to zero • b. What is the carrying capacity for snakes ? 15c. What is the carrying capacity for mice? 600-620 • d. What is the rate of growth for mice during 1970? +500 During 1980? -100
Density Dependent large, dense populations are more strongly affected than small, less crowded ones. EXAMPLES: Food Predators Water Disease Living space Density Independent Factors that can affect a population no matter what size it is EXAMPLES:Hurricane Forest fire Clear cutting Building dam Limiting Factors
Density-Dependent Limiting Factors • Competition • Predation • Parasitism • Disease • Living Space
DI DD DD DD or DI? fire predator Density of plants
DD DI DD DD or DI? cannibalism Cutting trees disease
HUMAN POPULATION GROWTH • http://www.gov.mb.ca/conservation/sustain/limfac.pdf • The world population is the population of humans on the planet Earth. It is currently estimated to be 6,874,700,000 by the US Census Bureau.
Human Population • How will the world population change in the future?
Human Population • Energy 365 Technology Basics: Population Growth : Video : Discovery Channel • Visuals: NOAA's nighttime lights of the world data set
China’s One-Child Policy • It officially restricts the number of children married urban couples can have to one, although it allows exemptions for several cases, including rural couples, ethnic minorities, and parents without any siblings themselves.[ 计划生育政策
Access to safe water and sanitation are two of the most fundamental indicators of public health.
Widespread HIV infection in sub-Saharan Africa is changing the region's demographic structure and impinging on its economic performance.
Before the 19th century, world population grew very slowly because high fertility was offset by high mortality. Improvements in population health, triggered partly by the industrial revolution, ushered in a period of rapid population growth.
Predator Prey Model • Predator Prey • Can change numbers of rabbits and foxes over years
Clumped Random Uniform