Initiation Assume that a pair of rabbits produces 6 offspring, and half the offspring are male and half are female. Assume no offspring die. If each pair of rabbits breeds only once, how many offspring would be produced each year for 5 years?

Unit 7 Ecology Discussion 7.3

SWBAT...identify factors that affect population size. Objectives SWBAT...identify factors that affect population size.

What factors affect population size? Key Questions What factors affect population size?

Words To Live By... Population density Carrying capacity Limiting factor

Key Points Three important factors can affect population size: the number of births, the number of deaths, and the number of individuals that enter and leave the population. The limiting factors of population growth can exist in two forms: density-dependent and density independent.

--------------------------- Population Density Number of Individuals Population Density = --------------------------- Unit area Suppose there are 150 bullfrogs living in a pond that covers an area of 3 square kilometers. What is the population density of the bull frog population?

How are these graphs alike? How are these graphs different? Population Growth How are these graphs alike? How are these graphs different?

Exponential Growth Vs. Logarithmic Growth Under ideal conditions with unlimited resources, a population will grow Exponentially. As resources become less available, the growth of a population slows or stops. This is called Logistic growth. Carrying capacity represents the maximum amount of individuals an environment can take.

Limiting Factors What are some things that might cause a population of organisms to decrease? A limiting factor is a factor that population growth to decrease. There are two major types of limiting factors: Density-Dependent Factors and Density-Independent Factors.

Density Dependent vs. Density Independent Which limiting factors do you feel depend on the size of the population to have any effect? Which limiting factors do you feel do not depend on the size of the population to have any effect? Dependent Independent Human Disturbances Competition Population Size Predation Climate Change Parasitism/Disease

Termination What is the difference between exponential and logistic growth? Which type graph represents growth under ideal conditions?