Transcript Chapter 35 Population and Community Ecology

Chapter 35
Population and
Community Ecology
• What is a population?
• A. Consists of all individuals of a species that live
together in one place at a time.
• What are some examples of a population that live
in an ocean?
• What is population density?
• A. Number of individuals of a particular specie
that live in a given area.
• How could we find the population density of Oxford?
• About how many people live in Oxford?
• A. 5,000
• B. 8,000
• C. 10,000
• D. IDK
A. 5,000
• What other information do we need to find out the
population density of Oxford?
• What is the area of Oxford?
• A. 1 square mile
• B. 2 square miles
• C. 6 square miles
• D. IDK
• A. 2 square miles.
• 5,000 people
----------------------2.00 square miles
= About 2,500 people per square mile in Oxford.
• Population in West Chester is 23,214.
• Area is 1.84 square miles.
• Will the population density in West Chester be
bigger or small than Oxford?
• Bigger
• About 12,616 people per square mile in West
Chester.
• Which city will have the highest population density?
Oxford, West Chester, or Philadelphia?
• How many people live in Philadelphia?
• A. 500,000
• B. 1,500,000
• C. 2,000,000
• D. 4,000,000
• B. 1,528,074 people live in Philadelphia
• Philadelphia is 135.1 square miles.
• 1,528,074 people / 135.1 square miles = 11,312 people
per square mile.
• Oxford= 2,500 people per square mile
• Philadelphia= 11,312 people per square mile
• West Chester= 12,616 people per square mile
• Why is Philadelphia’s population density smaller than West
Chester when it is so much bigger?
1. Certain areas may be uninhabitable.
2. Philadelphia has more stadiums, airports, restaurants,
roads, etc than West Chester.
3. More people move in and out of Philadelphia.
4. West Chester could be more desirable.
5. West Chester is awesome!
35.1 Population
How do scientists monitor plant populations?
• Use a method called quadrat sampling.
• Quadrats, or rectangular frames, are randomly
placed on a study site.
• Scientists count the number of plants within
each randomly selected plot. The total number
is plugged into a mathematical formula to
determine the entire site.
Sampling Technique
• Indirect counting are used for species that are
difficult to track. Scientists search INDIRECTLY
for other signs of its presence, such as feces,
nests, tracks, or a recent kill.
Mark-Recapture
• Use mark-recapture which is a method used by
scientists to estimate the populations size of
mobile organisms.
• Ie. Scientists capture and mark prairie dogs
with ear tags and release them back into the
wild.
• Scientists capture prairie dogs and calculate
the ratio of marked to unmarked animals to
estimate the population.
35.2 Population Growth
• Exponential Growth:
• Population multiplies by a constant factor at a
constant time interval.
• J shape curve:
Carrying Capacity
• Carrying capacity:
• Is the maximum number of individuals of a
particular species that the environment can
normally and consistently support.
• Population of deer. We put a small amount of
deer on a remote island. The island was lush for
green grass. What happened to the deer
population over time?
• S shape curve:
Limiting Factor
• Limiting factor:
• A condition that can restrict a population’s growth.
• Ex.
• Disease
• Limited food
• Space
Factors Affecting
Population Growth
• Density- Dependent Factors:
• A factor that limits a population more as
population increases.
• Ex.
• Disease that spreads more easily among
organisms in a dense population than in a less
dense population.
• Density- Independent Factors:
• Factors that limit populations but are unrelated
to population density.
• Ex.
• Weather events- hurricane, blizzard, droughts
Boom or Bust Cycle
• Increase rapidly for a period of time then
decrease rapidly for a period of time.
• Ex. Hares and Lynx
35.3 Human Population
Growth
• Most of history, human population growth was
very slow.
• 10,000 years ago saw a huge spike!
Why?
• Changes in human culture
• Wide scale farming provided more food
• Death rates decline because medicine
Predicting Future
Population
• Age Structure:
• Population is the proportion of people in
different age groups.
35.4 Species Interactions
What kind of people do you
interact with?
• Friends
• Parents
• Teammates
• Teachers
• Coaches
• Boyfriend/Girlfriend
What kind of relationships
do you have with them?
Story
• In terms of Arnold and I, what kind of
relationship did we have?
• +,--
• In terms of Nicole and I, what kind of
relationship do we have?
• +,+
What kind of relationship
do these organisms have?
• Human
• ___
• Mosquito
•+
What kind of relationship
do these organisms have?
• Black billed Magpie
•+
• American Bison
•+
Why does the tortoise have a neutral
relationship while the rodent and frog are
positive?
• Gopher Tortoise
•0
• Rodent
•+
• Frog
•+
• Interspecific Competition:
• When two or more species rely on same limited
source.
•
Ex.
• Africa Savanna
• When drought occurs all species rely on the
limited amounts of grass.
• Competitive exclusion:
• If two species are similar in their requirements
that the same resource limits both species
growth, one species may succeed over the other.
Competitive Exclusion
Niche
• Niche:
• An organisms role in the environment (its job)
• What is a plants niche?
• Photosynthesis and give us oxygen.
• Predation:
• In interaction in which one organisms eats
another.
Symbiotic Relationships
• Parasitism:
• One organisms benefits, other is harmed.
• Mutualism:
• Both organisms benefit
• Commensalism:
• One organisms benefits, the other is neither
harmed or benefited
Parasitism
Commensalism
Mutualism
35.5 Disturbances in
Communities
• Ecological Succession:
• Communities that change drastically as a result
of a disturbance such as fire, flood, storms,
drought.
• Primary succession:
• Community arises in a lifeless area that has no
soil.
• Secondary succession:
• When disturbances damages an existing
community but leaves soil intact.
Primary Succession
• Introduced Species:
• Organisms that humans move from species native land
to new areas.
• Ex.
• Kudzu plant from Japan to stop erosion.
Succession
Secondary Succession 1
Year
Secondary Succession 5
years
Secondary Succession 10
years
Secondary Succession 25
years
Secondary Succession 30
years