Chapter 5.1 – Population Growth

Daily Objectives List the characteristics used to describe a population. Identify factors that affect population growth. Compare and contrast exponential growth with logistical growth.

Think About It (not on notes) People in New England who fish for a living face a serious problem. Their catch has dropped dramatically, despite hard work and new equipment. The cod catch in one recent year was 3,048 metric tons. Back in 1982, it was 57,200 metric tons—almost 19 times higher! Where did all the fish go? Can anything be done to increase their numbers?

How Populations Grow What do you think will happen to the deer population if the wolves are removed from this ecosystem?

How Populations Grow Sea otters control the populations of kelp and sea urchins by eating them as a food source.

Characteristics of Populations 1. Geographic Range, is the area inhabited by a population - Range of Grey Wolf

Characteristics of Populations 2. Population Density refers to the number of individuals per unit area. Wildebeest live in densely populated herds

Characteristics of Populations 3. Population Distribution refers to how individuals in a population are spaced out across the range. Random Uniform Clumped

Characteristics of Populations 4. Growth Rate - A population’s growth rate determines whether the size of the population increases, decreases, or stays the same.

Characteristics of Populations 5. Age Structure - the number of males and females of each age a population contains. Why is this Important? Determines how many individuals are likely to reproduce in a population.

Factors that Affect Population Growth Birthrate and Death Rate - Populations can grow if more individuals are born than die in any period of time.

Factors that Affect Population Growth Immigration The movement of individuals into an area, is another factor that can cause a population to grow. Emigration The movement of individuals out of an area, can cause a population to decrease in size.

Exponential Growth Individuals reproduce at a constant rate. Under ideal conditions, a population will grow exponentially.

Logistic Growth Population growth slows or stops following a period of exponential growth Carrying capacity – the largest number of individuals that the environment can support