Do Now 4/16 (pass up do nows, HW out for checking, pls.) OBJECTIVE: 1.Describe the characteristics of populations using the terms size, density, dispersion, and age structure. 2.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 km 2 (about 80 mi 2 ) What is the human population density of Baltimore? 1.In people / km 2 2.In people / mi 2

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 km 2 (about 80 mi 2 ) What is the human population density of Baltimore?

Population Dispersion: How a population is distributed

Human Population Dispersion

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

Growth Curves Logistical / Linear Exponential Logistical / Linear

Exponential Growth

Human Population Growth In the 15 years since this graph the human population has Grown by over 1,000,000,000 people.

Resource Limits 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. One limiting resource constrains growth: Leibig’s Law of the Minimum

Typical Growth Curve

Survivorship Curves 3 Strategies for success: –Type I: low # of offspring, high survival rate of young. –Type III: high # of offspring, low survival rate of young. –Type II: moderate # of offspring and survival rate of young.

Total area = 3 km 2 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