Do Now 4.5 (Advisory Schedule) OBJECTIVES: Describe the characteristics of populations using the terms size, density, dispersion, and age structure. Describe and compare linear growth and exponential growth. TASK: Answer, don’t copy: There are approximately 640,000 people that reside in Baltimore City The land area of Baltimore is about 200 km2 (about 80 mi2) What is the human population density of Baltimore? In people / km2 In people / mi2

Measuring Populations Population size: how many organisms are in the population Population density: how many organisms there are per unit area (i.e. square km) Population dispersion: how individual organisms are arranged in the population Age structure: the relative distribution of organisms by age in the population

Population Size How many organisms are there? Simple count Sampling and average. A microbiologist samples a population of bacteria by counting the number of cells in 1 mL of the liquid they’re in, with the following results Sample 1: 27 individuals Sample 2: 33 individuals Sample 3: 30 individuals What is the population size if there are 100 mL of solution all together?

Population Density = Number/Area There are approximately 640,000 people that reside in Baltimore City The land area of Baltimore is about 200 km2 (about 80 mi2) What is the human population density of Baltimore?

Population Dispersion: How a population is distributed

Human Population Dispersion

Population Growth Rates Growth Rate: The amount by which the size of a population changes in a given time Birth Immigration Emigration Death / Mortality

Growth Curves Logistical / Linear Exponential Logistical / Linear

Exponential Growth

Human Population Growth In the 27 years since this graph the human population has Grown by over 2,000,000,000 people.

Populations will grow until there is something that limits them Food, water, or other resources Predators, parasites, disease, etc. Carrying Capacity: The maximum population that is sustainable for long periods of time in an ecosystem. Resource Limits One limiting resource constrains growth: Leibig’s Law of the Minimum

Typical Growth Curve

Do Now 4.6 OBJECTIVES: TASK: Describe and differentiate the three basic survivorship curves of different reproductive strategies TASK: Complete the first part of the populations practice problems from yesterday (drawing 2 populations)

Ooops… decimals… Houston, we have a problem The assignment P259 (participation weeks 25-29) was incorrectly entered with a 40x multiplier (instead of 4.0x) As a result, the grade some of you will receive for the 3rd quarter may be slightly inaccurate (+/- 0-3 points) Adjustments will be made to 4th quarter grades The list…

Survivorship Curves 3 Strategies for success: Type I: low # of offspring, high survival rate of young. (aka k-selection) Type III: high # of offspring, low survival rate of young. (aka r-selection) Type II: moderate # of offspring and survival rate of young. Survivorship Curves

Number of offspring per reproductive cycle Octopus v. Giant Panda Number of offspring per reproductive cycle ~200,000 1-2 Frequency of cycle 1 / lifetime 2 years, 6-8 times / lifetime Gestation ~ 6 months (external eggs) ~ 4 months Parenting 1.5 – 2.0 years

Find size, density, dispersion, and age structure of this population. Total area = 3 km2 Blue = young, white = old, turquoise = middle aged Find size, density, dispersion, and age structure of this population.

Population Growth Classwork / Homework Practice worksheet Reading on Syllabus