Population Dynamics (4.1) SB4C. Relate environmental conditions to successional changes in ecosystems.

Population Ecology HOMEWORK:Chapter 4 4.1 textbook - read/notes Population Ecology CC Ecology #2 – watch/notes

The number of organisms per unit area Chapter 4 Population Ecology Population Characteristics (AKA Demographics) 3 Main ways to describe populations: 1. Population Density The number of organisms per unit area 2. Spatial Distribution Dispersion is the pattern of spacing of a population. 3. Growth Rate

WHY & How Are Populations Measured? DO THIS! Density: measurement of population per unit area or unit volume Pop. Density = # of individuals ÷ unit of space What is the population density of humans in this classroom? (11m x 11m) Population density = number of individuals in a given area or volume Count all the individuals in a population Estimate by sampling Mark-Recapture Method

A C B

Dispersion is the pattern of spacing of a population. Population Ecology 2. Spatial Distribution Dispersion is the pattern of spacing of a population. Uniform – equally dispersed – territorial animals Clumped – groups – herding animals Random – no pattern – usually based on resources

Population Dispersion

Population Range 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

density-independent factors density-dependent factors. Population Ecology Population-Limiting Factors There are two categories of limiting factors — density-independent factors density-dependent factors.

Density-Independent Factors (generally abiotic) Population Ecology Population Limiting Factors Cont’d Density-Independent Factors (generally abiotic) Any factor in the environment that does not depend on the number of members in a population per unit area is a density-independent factor. Weather events Fire Human alterations of the landscape Air, land, and water pollution

Would you want to be in an area with high population density or low population density during the Zombie Apocalypse? Side note/thought…Is cell phone use a population density independent or density dependent factor? *We seem to use our phones more when there are more people….WHY? Are we afraid someone might talk to us? Is it as contagious as a yawn?

Density-Dependent Factors Population Ecology Population Limiting Factors Cont’d Density-Dependent Factors Any factor in the environment that depends on the number of members in a population per unit area is a density-dependent factor. Biotic factors Disease Competition Parasites

Growth Rate is affected by… Population Ecology Population Growth Rate The population growth rate (PGR) explains how fast a given population grows. Growth Rate is affected by… Limiting Factors Natality (# of births) Mortality (# of deaths) Immigration (# of individuals entering) Emigration (# of individuals exiting)

Factors That Affect Future Population Growth IN Immigration + + - Population Mortality Natality A population stops increasing when natality is less than mortality or when emigration exceeds immigration. - EXIT Emigration

Exponential Growth Model Population Growth Rate Cont’d Population Ecology Exponential Growth Model Graph shows a J-shaped Curve! Exponential growth occurs when the growth rate is proportional to the size of the population. All populations grow exponentially until some limiting factor slows the population’s growth.

Exponential Growth Curve Figure 35.3A

Population Growth Rate Cont’d Population Ecology Logistic Growth Model The population’s growth slows or stops following exponential growth, at the environment’s carrying capacity (k). Carrying capacity (k) is the largest # of individuals an environment can support. Graph shows an S-shaped Curve! Carrying capacity is limited by the energy, water, oxygen, nutrients, & space, as well as other limiting factors.

Logistic Growth Curve

Population Ecology Reproductive Patterns Species of organisms vary in the number of births per reproduction cycle, in the age that reproduction begins, and in the life span of the organism.

Population Ecology Reproductive Patterns Cont’d The rate strategy, or r-strategy, is an adaptation for living in an environment where fluctuation in biotic or abiotic factors occur. An r-strategist is generally a small organism. Short life span Produces many offspring EXAMPLES ???

Reproductive Strategies R Strategists Short life span Small body size Reproduce quickly Have many young Little parental care Ex: cockroaches, weeds, bacteria

Population Ecology Reproductive Patterns Cont’d The carrying-capacity strategy, or k-strategy, is an adaptation for living in stable environments. A k-strategist is generally a larger organism. Long life span Produces few offspring EXAMPLES ???

Reproductive Strategies K Strategists Long life span Large body size Reproduce slowly Have few young Provides parental care Ex: humans, elephants

“Booms” and “Busts”

Rabbit/Lynx LAB Rabbit Hunting!

A&P Exam – Post Exam Review

If you want to get all people human focused… Demography – the study of human population size, density, distribution, movement, and birth/death rates. HUMAN POPULATION GROWTH

AGE/SEX Demographics Distribution of males and females in each age group of a population Used to predict future population growth

Human Population Growth J curve growth Grows at a rate of about 80 million yearly r =1.3% Why doesn’t environmental resistance take effect? Altering their environment Technological advances The cultural revolution The agricultural revolution The industrial-medical revolution

History of the Human Population

The Human Population Doubled three times in the last three centuries About 6.1 billion and may reach 9.3 billion by the year 2050 Improved health and technology have lowered death rates

A more personal story… Overpopulation a MYTH?

SmartStarter Take a GUESS:

Chapter 4 Population Ecology Chapter Diagnostic Questions What term is used to describe the number of individuals moving into a population? emigration imitation immigration migration A B C D CDQ 1

What is population density? Chapter 4 Population Ecology Chapter Diagnostic Questions What is population density? pattern of spacing of a population in an area number of organisms in an area characteristics of a population manner in which a population grows A B C D CDQ 2

Which is a density-dependent factor? Chapter 4 Population Ecology 4.1 Formative Questions Which is a density-dependent factor? disease fire flooding weather A B C D FQ 1

Which is a density-independent factor? Chapter 4 Population Ecology 4.1 Formative Questions Which is a density-independent factor? competition extreme cold parasites predation A B C D FQ 2

Which factor can limit the carrying capacity of a population? Chapter 4 Population Ecology 4.1 Formative Questions Which factor can limit the carrying capacity of a population? emigration predation available nutrients extreme temperatures A B C D FQ 3

Which type of population growth model does this graph represent? Chapter 4 Population Ecology Chapter Assessment Questions Which type of population growth model does this graph represent? exponential spatial genetic logistic A B C D CAQ 1

Use the graph to explain the growth of the mice population. Chapter 4 Population Ecology Chapter Assessment Questions Use the graph to explain the growth of the mice population. CAQ 3

Chapter 4 Population Ecology Standardized Test Practice The ecologist finds that over a 1000m2 plot of tundra, lemmings tend to concentrate in clumps in drier areas. What is the term for this pattern of spacing? density dispersion logistic spacing spatial distribution A B C D STP 2

It is density-dependent. It is limited by biotic factors. Chapter 4 Population Ecology Standardized Test Practice Brine shrimp are able to survive only in certain lakes that have a very high salt concentration. Which is the correct population characteristic of brine shrimp? It is density-dependent. It is limited by biotic factors. It has a limited spatial distribution. It is randomly dispersed in the environment. A B C D STP 3

Standardized Test Practice Chapter 4 Population Ecology Standardized Test Practice Why does the population growth level off at 10,000? Biotic factors have made survival difficult. The population has reached its carrying capacity. Density-independent factors have slowed the growth of the population. Immigration into the population has reached the maximum limit. A B C D STP 4

Which organism is the best example of a k-strategist? Chapter 4 Population Ecology Standardized Test Practice Which organism is the best example of a k-strategist? wolf grasshopper rabbit whale A B C D STP 5