Final exam review – Fall 2013
Ecology Topics
Symbiosis
• relationship where there are close and longlasting associations between orgs of different
species
Types:
a. parasitism – tick on a dog
b. commensalism – barnacle on whale
c. mutualism – honeybee and flower
Types of Population Growth
• Exponential Growth
• Logistic Growth
1. Exponential Growth
• J-shaped curve
• reproduce at a constant rate
– Slowly at first, then larger until
approaches infinitely large
size.
• ideal conditions
• unlimited resources
2. Logistic Growth
• S-shaped curve
– Slow increase, larger increase when large
number of resources, then slows when
resources become less available, growth
slows/stops, oscillates around carrying
capacity.
• Carrying Capacity– largest # individuals environment
can support
– Tells size of population when
average growth rate reaches zero.
How could growth
slow or stop?
Matter and Energy Flow in
Ecosystems
Energy flows through organisms in an
ecosystem. IT DOES NOT RECYCLE!
 Matter is neither created nor destroyed, it
CYCLES
 Scientists use models to represent these
pathways.

2 models: food chains and food webs
*food webs are made up of many
interwoven food chains…
Food Chains
Nutrients and energy move from autotrophs to
heterotrophs to decomposers…
 Food chains are drawn with arrow pointing in
direction of energy flow – org that consumes will
have “mouth” to eat food source.

grasshopper

robin
robin
grasshopper
 Food chains can be made up 3 links, but seldom
have more than 5 due to loss of energy as heat.

food webs video clip
Pyramid of Biomass and 10% rule
Represents the amount of
living organic matter at each
trophic level. Typically, the
greatest biomass is at the
base of the pyramid.
Carbon and Nitrogen cycles

Carbon cycle

Nitrogen cycle
Succession

Primary vs. Secondary succession

Which is this?

Animated example
Types of biomes
Aquatic
1. marine biomes (saltwater)
2. freshwater biomes
Terrestrial
3.
4.
5.
6.
7.
8.
tundra
taiga (coniferous forest)
desert
temperate grassland
savanna
temperate deciduous
forest
9. tropical rain forest
http://www.blueplanetbiomes.or
g/world_biomes.htm
ADAPTATIONS – What traits make organisms
suited for the challenges of their environments?
AKS Bio Bio 11e) Relate plant adaptations,
including tropisms, to ability to survive stressful
conditions
•Match the following plants with their correct
habitats:
pine tree
venus fly trap
banana plant
cactus
•Habitats: Desert, Temperate Forest Bog,
Tropical Rainforest, Desert
AKS Bio Bio 11e) Relate plant adaptations,
including tropisms, to ability to survive stressful
conditions
•Match the following plants with their correct
habitats:
pine tree
Taiga
venus fly trap
Temperate Forest Bog
banana plant
cactus
Tropical rainforest
Desert
Below is called a TRACKING GRAPH – because the peaks
of the predators always follow the peaks of the prey
Population Density
• # of individuals in population per unit area
– (# individuals) / (area)
– Varies depending on species in ecosystem
– Increase density = increase crowdedness
Types of Competition
• Interspecific
• Intraspecific
Interspecific Competition
Competition between different species for the
same resources.
wildebeast and rhino
vultures and hyenas
Intraspecific Competition
•Competition between members of same species
for similar resources.
herons
lions
Bunchgrass in Mojave Desert –
roots compete
Limiting factors


Def: any environmental factor (whether
abiotic or biotic) that restricts the
existence, numbers, reproduction, or
distribution of organisms in an
ecosystem.
(Ex. Amount of food, predators,
temperature)
Factors that limit one population may also
have an indirect effect on another
population.
Organisms in Ecosystems
where an org lives its day-

Habitat – place

Niche – the role and position a species occupies
in its habitat or location. HOW it lives in
to-day life.
(habitats can change dramatically due
to natural or man-made effects:
Ex. fire because of lightning or
careless campers...
the habitat…This includes all of the org’s
interactions with the living and nonliving parts of
the habitat.
Ex. Earthworms act as decomposers
Threats to Biodiversity
(Human Impact):
1. Habitat loss/destruction
(this one is the number one concern!)
2. Habitat fragmentation
3. Habitat degradation
4. Introduction of Exotics/Invasive
Species
Threats to Biodiversity
• Habitat loss – destruction of area
*deforestation
*clear-cutting grasslands
*draining wetlands
• Habitat degradation
(damage to habitat by pollution)
Pollution: any undesirable factor that is
added to air, water or soil.
*3 types of pollution:
air, land, water
Habitat degradation leads to..
• Greenhouse effect and global warming
• Algal blooms
• Loss of species

Biological Magnification
Page 495
Introduction of
Exotic species or Invasive Species
• “Exotic” meaning not native to an area
• Problem is that there are NO NATURAL
PREDATORS, so the new species grows
unchecked and can get out of control
• Ex. Kudzu, fire ants, zebra mussels
Ultimate goals:
• Conservation biology
• sustainable use practices (nature
preserves)
• Legal protection of species
• Habitat corridors
• Recycling and reusing