Populations Please begin reading “Death in the Rainforest”

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 about 1,000,000,000 people.

Age Structure

Total area = 3 km 2 Blue = young, white = old, turquoise = middle aged Find size, density, dispersion, and age structure of this population.