Populations Objective Discuss what a limiting factor for population growth is. Limiting factor Density-dependent limiting factor Density-independent limiting factor Homework Study for exam on Friday!!! Do now!! Define/describe the following terms Energy pyramid Biomass Primary productivity Limiting nutrient

Chapter 5 Populations

Characteristics of Populations Geographic distribution The area in which a population lives population density Density – population density The number of individuals per unit area Growth rate The rate at which a populations grows

Factors of Population Growth The number of births The number of deaths The number of individuals that migrate into or out of the population. Immigration – the movement of individuals into a population. Emigration – the movement of individuals out of a population.

Exponential Growth Occurs when the individuals in a population reproduce at an increasing rate. Under ideal conditions with unlimited resources, a population will grow exponentially.

Logistical Growth As resources become less available, the growth of a population slows or stops. Logistical Growth - growth pattern in which a population’s growth rate slows or stops following a period of exponential growth carrying capacity largest number of individuals of a population that a given environment can support

5-2 Limits to Growth The primary productivity of an ecosystem can be reduced when there is an insufficient supply of a particular nutrient. What is this nutrient called? Limiting Nutrient A limiting nutrient is a specific example of the general concept of a limiting factor – factor that causes the growth of a population to decrease

Limiting Factors Density Dependant Factors Density Independent Factors

Population Trends Do fruit flies and rabbits show similar trends in population growth? Using Tables and Graphs Make a graph using the data in each data table. One graph will show the growth rate of a fruit fly population. The other graph will show the growth rate of a population of rabbits. Analyzing Data What type of growth pattern is exhibited by the fruit fly population? Is it the same type of growth as in the rabbit population? Explain. Drawing Conclusions Does either graph indicate that there is a carrying capacity for the population? If so, when does the population reach its carrying capacity? What is the maximum number of individuals that can be supported at that time? Predicting Animals such as foxes and cats often prey on rabbits. Based on the growth curve of the rabbit population, what might have happened if a group of predators moved into the rabbits’ habitat during the tenth generation and began eating the rabbits?

Density-dependent Limiting factor. Affects a population based on the size of the population. The density of the rabbit population only affects a wolf population when the wolf population grows to large.(density increases) Density-dependent limiting factors include competition, predation, parasitism, and disease.

Density-dependent Factor

Predator-Prey Relationship mechanism of population control in which a population is regulated by predation.

Density-dependent Factor Predator-Prey Relationship mechanism of population control in which a population is regulated by predation.

Density-dependent Factor Parasitism and Disease Can limit the growth of a population.

Density-Independent Factor limiting factor that affects all populations in similar ways, regardless of population size. Unusual weather, natural disasters, seasonal cycles, and certain human activities—such as damming rivers and clear- cutting forests—are all examples of density- independent limiting factors.

Density-independent Factors

Homework Read PGS 129 – 132 Study Guide _ _______ number of individuals per unit of area 2. _______ movement of individuals into an area occupied by an existing population. 3. _______ movement of individuals out of a population. 4. _______ growth pattern in which the individuals in a population reproduce at a constant rate. 5. ________ growth pattern in which a population’s growth rate slows or stops following a period of exponential growth. 6. ________ largest number of individuals of a population that a given environment can support.

1. Key Concept List three density-dependent factors and three density-independent factors that can limit the growth of a population. 2. What is the relationship between competition and population size? 3. If an entire lynx population disappears, what is likely to happen to the hare population on which it preys? 4. Critical Thinking Applying Concepts Give an example of a density-independent limiting factor that has affected a human population. Describe how this factor changed the human population. 5. Define carrying capacity. 6. Critical Thinking Inferring What factors might cause the carrying capacity of a population to change?