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Population Ecology Every second….5 people are born, 2 people die, ….net gain 3 people.
Population Ecology Deals with the # of individuals of a particular species that are found in an area and how and why those # change or remain fixed over time.
Population ecologists study… How populations respond to its environment Competition for resources, predations, disease and other environmental pressures
Population Growth J-shaped curve 1. Exponential growth– growth rate under ideal conditions 2. Uncheck growth (carrying capacity not yet met)
J-shaped Exponential growth!
S-Shaped Curve 1. An S-shaped curve shows that the population grows slowly at first & then increases more and more quickly.
2. At carrying capacity, growth of the population will remain the same.
3. Carrying capacity is the number of organisms that an environment can support indefinitely.
A. Births will approximately equal DEATHS. B. When the population overshoots the carrying results in LIMITING factors death to outnumber births.
C. Limiting Factor is a factor that will limit population growth. 1) Food availability 2) Disease 3) Predators 4) Space
Reproductive Patterns A. Rapid life history (example: mosquitoes) a. Rapid reproduction b. High number of offspring
Reproductive Patterns c. Small body size d. Organisms mature rapidly e. Reproduce early f. Organisms have a short life span
B. Slow life history (example: elephant) a. Slow reproduction b. Low number of offspring c. Large body size
d. Organisms mature slowly e. Reproduce late in life f. Organisms have a long life span g. Organisms tend to have parental care
Population density & growth Population density is the number of individuals in a given area.
Density–DEPENDENT factor Factor that limits population size or density
A. Disease (example: HIV) B. Competition C. Predators D. Parasites E.Food F.Water G.Territory
Density -INDEPENDENT factor: Usually a weather related event. It affects ALL populations regardless of size.
A. Temperature B. Storms C. Floods D. Drought E. Volcanic eruption
Predator-prey relationship A.Predators affect prey populations B. Prey affect predator populations
Intraspecies competition A. Space B. Food C. Water D. Reproduction
Invasive Species – uncontrolled competition
Project World Population Growth Demography Study of HUMAN population size, density, distribution, movement, BIRTH rates & death rates.
World Population Growth
YearPopulation 1200 million million million million million billion billion billion billion billion billion billion billion billion billion billion billion billion billion billion billion billion billion billion billion
Humans can alter their environment thus affect the POPULATION GROWTH RATE.
1. Famine 2. Eradicate Disease 3. War 4. Better food production
Calculating Growth Rate Growth rate (r) = birth rate (b)+ I – death rate (d) + E
Immigration – movement of individuals into a population Emigration – movement of individuals into a population
Doubling time – time needed for population to double in size Zero population growth – birthrate = death rate
Birthrate – number of live births per 1000 in a given year Death rate – number of deaths per 1000 in a given year
Demographics of Countries Demographics – applied science that deals with population statistics.
Developed countries 1. Low birth rates 2.Low infant mortality rates. (the # of infant deaths per 1000 live births)
Developed countries 1996 US 7.5/1000 for infant morality World average 62/1000
Developed countries 3.Usually have longer life expectancy
Developed countries 4.Examples of developed countries: US, Canada, Sweden, Germany, France, Australia, Japan
Moderately developed countries Examples: 1. Mexico 2. Turkey 3. Thailand (most S. American nations) Developing Countries
Less developed countries Examples: 1. Bangledesh 2. Niger 3.Ethiopia 4.Laos 5.Cambodia
These countries have ………… High birth and mortality rates than developed countries Short life spans
Another factor to examine is the replacement level fertility. This is number of children a couple must have to replace themselves. Replacement rate is 2.1 children in developed countries.
The replacement rate in developing countries is 2.7 children.
Age Structure of Countries In order to predict future population it is important to know the age structure.
Age Structure of Countries number age malesfemales Age structure is the number and proportion at each age in a population. The number of males and females at each age.
The overall structure of the age tells whether the population is increasing, stable or shrinking.
Stable growth – approximately the same number of individuals at each age grouping
Rapid growth – a large proportion of the population is 19 years old or younger
Slow growth – a large proportion of population is 55 years old or younger
Declining growth – the largest portion of the population is years, smaller groups are younger
Population Dynamics The change in the size, density, dispersion, and age distribution of a population in response to changes in environmental conditions.
Population Biology. Populations Population: a group of organisms of the same species that live within a given area Key characteristics: –Growth Rate –Population.
Population Density The number of organisms per unit area.
Click on a lesson name to select. Chapter 4 Population Ecology Section 1: Population Dynamics Section 2: Human Population.
Table of Contents – pages iv-v Unit 1: What is Biology? Unit 2: EcologyEcology Unit 3: The Life of a Cell Unit 4: Genetics Unit 5: Change Through Time.
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Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece.
Ecology – Population Growth and Regulation Ecology – the study of interrelationships among living things and their nonliving environment Environment –
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Population Ecology. Population Dynamics ______________________: all the individuals of a species that live together in an area ______________________:
Population Ecology Chapter 45. Population Ecology Certain ecological principles govern the growth and sustainability of all populations--including human.
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REVIEW CHAPTER 9. An increase in waterborne diseases could possibly be alleviated by A. Adequate sewage treatment facilities for growing populations B.
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Population Dynamics. Population Characteristics All populations have three main characteristics that are used to classify the population. 1.Population.
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Brainstorm You and the person next to you will list 3 examples of….. Abiotic and biotic factors that affect population growth and decrease in size.
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