Ecology powerpoints
Discover Biology
FIFTH EDITION
23 with parts of 21 & 22
Ecology in a nutshell
© 2012 W. W. Norton & Company, Inc.
Ecology: organisms and ecosystems
• biosphere – all earth’s living organisms & their
physical environments (living and non-living)
• Ecology - study of interactions between
organisms and their environment
biotic (living) and abiotic (nonliving)
Example: Effect of Water
• Oceans, large lakes and mountains affect
ecosystems
• Water gains and loses heat slowly
mild climate
lake effect
Mountains often produce a rain shadow effect,
in which little precipitation falls on the side of
the mountain that faces away from the
prevailing winds
Rain Shadow: Same Island
Biomes: regions of biosphere
• Biomes – divided by climate and ecological
features of each such region
• Terrestrial biomes - usually named after the
dominant vegetation
• Aquatic biomes - classified by physical or
chemical features
e.g. salt content
Introduced and invasive species
• Introduced species = in this location because
of human activity
• invasive species = Any introduced species that
becomes a major pest in a new environment
Zebra Mussels
Originally from
Russia
Brought over in ship
ballast water
Now quaaga
muscles (worse)
How Invasive Mussels Can Harm
Whole Ecosystems
• invasive species = Any introduced species that
becomes a major pest in a new environment
• zebra mussel outcompetes native mussels
• Eats all the algae: out of the Great Lakes and
left little for other aquatic species to eat
• Threatens fishermen in Great Lakes
•
http://www.pbs.org/newshour/bb/environment/july-dec11/mussels_11-23.html
Florida: Introduced & Invasives
• Introduced species = citrus trees
• invasive species =
pythons
iguanas
monitor lizards
snails
Huge pythons eat EVERYTHING
• http://www.usgs.gov/blogs/features/usgs_top_story/under-siegeamerica%E2%80%99s-most-unwanted-invasive-species/
• http://news.nationalgeographic.com/news/2006/05/060524-iguanas.html
Iguana in the toilet at Boca Grande!
•
http://www.tampabay.com/news/environment/wildlife/article1011745.ece
Giant lizards eat Cape Coral!!
http://abcnews.go.com/blogs/headlines/2011/09/giant-african-snails-invade-miami-florida/
Giant Snails eat Florida houses!!!
What Is a Population?
population = all individuals of one species in
an area
Population size = # of individuals in population
Population density = # of individuals per unit of
area
Exponential Growth
what happens when
there are no limits
on resources
Can not last for long in
nature (always some
kind of limiting
factor)
Logistic Growth & Limits
• Populations cannot increase in size indefinitely
• Some resource will become limited
space
nutrients
habitat
Logistic Growth: normal in nature
• Logistic growth = S-shaped curve
resources become limited
Logistic Growth: normal in nature
• carrying capacity = maximum population size
in a given environment
• At the carrying capacity, the population
growth rate is zero
Population Crash: the unlucky option
If you use up a resource too quickly, you may
not slow down as you near carrying capacity
Population Cycle
population cycle = two or more species have
populations change together (mutual influence)
Hare predation affects lynx
population
Lynx (food) availability
Affects lynx population
Patterns of Population Growth
• Most populations have irregular fluctuations
• Populations of the same species may
experience different patterns of growth
What Does the Future Hold?
Most research indicates that the current human
impact on Earth is unsustainable
Community: Not the mediocre sitcom
community = several populations in same area
grass, rabbit, deer, squirrel, oak tree
Community Diversity
• Some communities have more diversity than others
• 2 parts to diversity:
– Species richness
– Relative species
abundance
Types of Species Interactions
Everything in nature either makes its own food
or eats something else for food
Types of Consumers
Herbivores: eat producers (plant/algae)
Predators: eat prey (other animals)
Omnivores: eat many things (plant or animal)
Food Chain
Apex Predator: top of food chain
Usually a Tertiary or Quaternary consumer
(Most ecosystems don’t have enough energy to go higher)
Trophic Levels and Energy
Most organisms use around 10% of the energy
they take in.
Less food available at top
Blue whale: biggest
animal EVER
Eats low on food chain:
More food is available
Food Chains vs. Food Web
• food chain simplified linear sequence
• A food web shows some of the complexity of
the relationships in a community
• Organisms may eat an multiple trophic levels
Relationships: Symbiosis
Sym (“same”) + bio(“life”) = symbiosis
When organisms live together.
mutualism – good for both
commensalism – good for one
parasitism – good for one, bad for one
Relationships: Symbiosis
– Mutualism: both species benefits
Relationships: Symbiosis
– Commensalism: one benefits, little effect on other
Relationships: Symbiosis
– Parasitism: one benefits, the other is harmed
nuisance: tapeworm in dog
deadly: heartworm in dog
“host”: what parasite feeds on
It is often better to leave your host alive so you can
continue to use them.
Exception: you may need another host (T. gondii)
Parasites can change behavior
• Toxoplasma gondii is a single-celled parasite,
most often contracted from raw meat, that
alters the brain activity of rodents
How a Parasite Can Hijack Your Brain
• T. gondii improves its chances of spreading to
cats by changing the behavior of infected rats
• Studies indicate T. gondii infections in humans
also alter behavior…also more risky choices
Relationships: Competition
• competition = two species in same place want
same lifestyle/resource
• niche = resources and conditions needed for a
lifestyle (job)
• Competitive exclusion = winning species stays.
Looser moves away or dies out (looser is excluded
from the niche)
Competition (2 more ways)
• Interference = keep other species away from
resource
• Try to use more of resource than other species
Niche partitioning
• Reduce competition by using niche in different
way. (loser finds a way to not be chased off)
Consumers can cause natural selection
Traits that help you not get eaten are passed on
Induced defenses = plants attacked by
herbivores (spines, chemicals)
Other Defensive Adaptations
Cryptic coloration & Camouflage
Warning Coloration
Mimicry
Batsian
Muellarian
Cooperation
Defensive Adaptations: camoflauge
Trying not to be
Seen by predators
Defensive Adaptations: warning coloration
Traits that help you not get eaten are passed on
• Warning coloration = “you’ll regret it if you
eat me or bother me”
Defensive Adaptations: Mimicry
Mimicry = looking like something else
Muellerian Mimicry = Member of group you
should avoid
Bastian Mimicry = Bluffing. Look like you are a
member of a group to avoid
Mullerian Mimicry: Member of group
Insects with “gang
colors”
Black and yellow
stripes mean
“leave me alone”
Shared warning
coloration
Batsian Mimicry: Bluffing
When a defenseless organism tries to look
like one to avoid
Ugandan jumping spider (tasty)
Tetraponera twig ant (stinging)
Batsian Mimicry: Bluffing
When a defenseless organism tries to look
like one to avoid
Warning coloration
Batsian Mimic
Defensive Adaptations: cooperation
Working together against predators
Keystone
• Most important part of an arch
• Remove it an the arch falls down
• Small part, but ultra important for entire arch
Keystone Species: big effects
• Keystone species = low numbers but have an
important job in ecosystem
• Producer or consumer
• removing them from ecosystem causes a HUGE
change
Clicker Questions
CHAPTER 23
Ecological Communities
Concept Quiz
Organisms that must survive by eating other
organisms are called
A. Producers
B. Consumers
C. Herbivores