CHAPTER 4 POPULATION ECOLOGY Section 4 1 Population
- Slides: 21
CHAPTER 4: POPULATION ECOLOGY Section 4. 1: Population Dynamics Section 4. 2: Human Population
• Graphing population growth isn’t like graphing the amount you get paid at a job or how many averages pages you can read in a book per hour Linear Line
• Graphing population will display a J-shaped curve. WHY? • This illustrates Exponential Population Growth
Exponential Growth Model § Exponential growth means that as a population gets larger, it also grows faster. § All populations grow exponentially until some Limiting Factor slows the population’s growth.
Logistic Growth Model § The population’s growth slows or stops following exponential growth, at the population’s Carrying Capacity.
• Until the Industrial Revolution in the 1800 s, human population growth was relatively slow. • During the Industrial Revolution, a sharp increase in human population growth began. • Today the Earth has reached a population of over 7 billion people • This is double the population of 1965
Carrying Capacity § The maximum number of individuals in a species that an environment can support for an indefinite period of time § Carrying capacity is limited by the energy, water, oxygen, and nutrients available (limiting factors)
Population-Limiting Factors § There are two categories of limiting factors §Density-independent factors §Density-dependent factors.
Density-Independent Factors § Any factor in the environment that does not depend on the number of members in a population per unit area § Weather events § Fire § Human alterations of the landscape § Air, land, and water pollution
Density-Dependent Factors § Any factor in the environment that depends on the number of members in a population per unit area § Biotic factors § Disease § Competition § Parasites
Population Ranges • A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region. Common dolphin Pupfish
Human Population Growth § Demography = the study of human population size, density, distribution, movement, and birth and death rates is.
§ A population stops increasing when the number of births is less than the number of deaths or when emigration exceeds immigration. §Births < deaths §Emigration > immigration To calculate a country’s population growth rate: Birthrate – Death rate = Population Growth Rate (PGR)
Zero Population Growth § Zero population growth (ZPG) occurs when the birthrate equals the death rate. § The age structure eventually should be more balanced with numbers at prereproductive, and postreproductive ages being approximately equal.
Age Structure §A population’s age structure is the number of males and females in each of three age groups: Pre-reproductive Stage, Reproductive Stage, and Post-reproductive Stage.
Comparing Age Structures • Replacement occurs when a couple has only two children. • If there is an average of more than two children born to each couple, the population will grow. • A graph of the number of individuals of each age can show if the population is stable, growing or declining. • A growing population will have a pyramid shaped age structure graph
Increasing Population Decreasing Population
Stable Population
Human Population Growth Rate • Although the human population is still growing, the rate of its growth has slowed • Because of the rapid increase in the human population, there are concerns that the human population may someday reach its carrying capacity
Trends in Human Population Growth § Population trends can be altered by events such as disease, war, & zombies. § Human population growth is not the same in all countries.
• The more-developed countries have modest population growth rates due largely to decreased birthrates. WHY? • The less-developed countries have higher population growth rates because birthrates remain high. WHY?
- Chapter 4 population ecology section 1 population dynamics
- Population ecology section 1 population dynamics answer key
- Section 1 population dynamics
- Population ecology section 1 population dynamics
- Chapter 53 population ecology
- Equilibrial life history
- Chapter 4 population ecology answer key
- Chapter 53 population ecology
- Section 1 population dynamics answer key
- Chapter 53 population ecology
- Chapter 3 section 1: community ecology
- Section 1 organisms and their relationships answer key
- Principles of ecology chapter 2
- Chapter 2 section 1 organisms and their relationships
- Principles of ecology chapter 2 section 1 answer key
- Logistic growth ecology definition
- Logistic growth ecology definition
- Fig 52
- Ecosystem vs community
- Concept 3 population ecology
- Lynx and hare relationship
- Characteristics of population ecology