Transcript Chap 4 and 5 ppt - Leon County Schools

Population Ecology
Chapter 4:
Main Idea:
Human population growth changes over time.
Section 1
• Characteristics of Populations
• Population Limiting Factors
Section 2
• Human Population Growth
• Trends in Growth
Populations
• Groups of the same species, living in
the same area, at the same time!
Population Characteristics
1. Population Density (# per unit area)
How many are in a given amount of space?
Population density is highest when resources
are abundant and when body size is small.
2. Spatial Distribution
• Dispersion is the pattern of spacing within an area.
• Uniform
• Random
• clumped
• Affected by availability of resources
Population Limiting Factors (2)
1. Density independent factors:
Any factor in the environment that does not
depend on the number of members in the
population per unit area. (the density!)
Usually abiotic, including natural phenomena
and weather events like drought, floods,
extreme heat or cold.
Example of density independent:
Flooding
Few lemmings
Lots of lemmings
2. Density dependent factors
• Any factor in the environment that depends
on the number of members in a population
per unit area.(the density!)
• Usually biotic such as predation, disease,
parasites, competition.
Example of density dependent: predation
Predation
Graphs of 2 populations often show a rise
and fall in population size demonstrating
the dependence on one another
Number of nesting sites:
density dependent
Population Growth Rate
(4 terms)
• How fast a population grows or increases
in size.
1. Natality = # of organisms born (birthrate)
2. Mortality = # of organisms that die
3. Emigration
(exit)
The number of individuals moving away
from a population
• How does emigration affect a population?
Initially it makes the population smaller due
to the loss of organisms.
BUT, less competition, more resources
could increase the birth rates and eventually
allow the population to have a growth rate
increase.
4. Immigration (to come in)
The number of individuals moving into a
population.
Types of Population Growth:
Exponential (J curve)
Logistic (S curve)
No limits= exponential growth
• Lots of food, lots of space, no competition,
no predators …growth will go on and on…
Exponential growth J curve
Logistic Growth S curve
• Growth starts with a lag phase, grows rapidly,
but reaches the carrying capacity and stops
increasing.
• Fewer births than deaths or emigration
exceeds immigration.
Logistic Growth S curve
Carrying Capacity
• The maximum number of individuals in a
species that an environment can support
for the long term.
• Limited by energy, water, oxygen, and
nutrients available
How does the carrying capacity affect the
reproductive rates?
Ex:
How will the reproductive rate be affected
if the population is below the carrying
capacity?
What does this look like on a graph?
Reproductive Patterns:
r-strategy
k-strategy
What if you live in an environment that fluctuates (changes)?
r – strategy:
Have lots of babies, don’t take care of them!
Doesn’t take much energy.
Ex: rabbits, fruit flies, locusts
What if you live in a stable environment?
k-strategy:
Have a few babies and take very good care
of them.
Takes a lot of energy!
Ex: kangaroos, humans, polar bears, elephant
r Unstable environment, density
independent
small size of organism
energy used to make each individual is
low
many offspring are produced
early maturity
short life expectancy
each individual reproduces only once
survivorship pattern
in which most of the individuals die
within a short time
but a few live much longer
K Stable environment, density
dependent interactions
large size of organism
energy used to make each individual is
high
few offspring are produced
late maturity, often after a prolonged
period of parental care
long life expectancy
individuals can reproduce more than
once in their lifetime
survivorship pattern
in which most individuals live to near the
maximum life span
Section 2
Human Populations
Demography:
Human population size
Density
Distribution
Movement
Birth and death rates
Age Structure Diagram
Current Growth Rate = 80 million people
per year
Rate of growth is slowing.
Decline due to disease (AIDS), birth
control, education
Zero population growth:
Births = deaths
Human carrying capacity?
What are we using the energy for?
Chapter 5
Biodiversity and Conservation
Section 1: Biodiversity
Types of Biodiversity
Importance of Diversity
Section 2: Threats to Biodiversity
Types of Extinctions
Specific Threats
Section 3: Conserving Biodiversity
Natural Resources
Specific Protections
Types of Biodiversity (4)
1. Biodiversity: variety of life in an area
2. Genetic Diversity: variety of genes in a population
3. Species Diversity:
# of different species and abundance of each
This increases as you move toward the equator
where the environment is more stable.
Increased diversity near the equator!
4. Ecosystem Diversity:
variety of ecosystems in the biosphere
Importance of Diversity
Economic Value: clothing, food, energy, medicine
Aesthetic Value: beauty
Inherent Value: Protect biodiversity just because
we should
Section 2
Threats to Diversity
2 types of Extinction:
Background extinction: gradual, natural process
Mass Extinction: large scale extinction, accelerated rate
99% of all species that ever existed on Earth are now extinct.
These extinctions mark some of the great transitions in life, when new groups
of species got the opportunity to take over the niches of old ones. Mammals,
for example, only dominated the land after giant dinosaurs vanished 65
million years ago in the Cretaceous-Tertiary extinction. We humans, in other
words, are the children of extinctions.
http://evolution.berkeley.edu/evolibrary/article/history_08
TODAY:
Current rate of extinction is 1,000 times the normal rate.
1/3 to 2/3 of all plants and animal species will be extinct
by the year 2100.
Many are on islands (can’t escape).
Humans are changing conditions on earth faster than
organisms can adapt (evolve).
Specific Threats:
Overexploitation: hunting, fishing
Habitat Loss:
– human encroachment
– deforestation
Habitat Fragmentation: roads, subdivisions,
pipelines
Pollution
Biological Magnification:
when the apex predator dies from accumulated toxins
Ex: DDT (pesticide) and birds eggs
Acid Rain: due to pollution by humans!
Compounds react in the atmosphere to produce sulfuric and nitric acid.
Eutrophication:
Excess nutrients flow into aquatic ecosystems resulting in algal blooms.
Oxygen used up, fish die!
Introduced (invasive) species:
Species that are not native to the area.
Introduced species are a greater threat to native biodiversity than pollution,
harvest, and disease combined.
Florida:
Fire Ant
Hydrilla
Ball Python
Mimosa
Lantana
Cuban Tree Frog
Green iguanas
Spice berry
Mimosa tree
hydrilla
The End
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