Transcript Species Interactions

Populations are limited
Limiting Factors : things in the environment that keep a
population from growing out of control
Limiting factors
Density-independent limiting factors
 These are not dependent on the size of the population
 Examples: natural disasters, weather, human
destruction of habitat
Limiting factors
Density-dependent limiting factors
Effects of these depend on the size of the population
Examples:
 disease
Tasmanian devil
population threatened by
contagious disease called
devil facial tumor disease
Limiting factors
Density-dependent limiting factors
Example:
Species Interactions
 Competition
 Predation
 Symbiosis
Niche
Definition: the role of a species within an ecosystem
Not just the habitat, but how it interacts with other
organisms, too
Competition
Definition: when two or more individuals or
populations try to use the same limited resource
Both are negatively affected by the interaction
Types of competition
Interspecific competition – competition
between members of different species
Example: plants compete for limited nutrients in
the soil around them, light, water, space, etc.
1.
Interspecific competition
Organisms have different adaptations to improve
competitive edge – a few examples:
 produce many offspring
 have extensive root systems that are efficient
 extremely fast growth rate
 allelopathy – when a plant produces a chemical
that prevents other plants from growing around it
(black walnut, sunflowers, junipers)
 aggressive behavior
Interspecific competition
Example: warblers – different species of small songbirds
that are similar in habit, compete for the same
resources in trees
Bay-breasted warbler
Cape May warbler
Yellow-rumped warbler
Niche partitioning
Reduces interspecific competition by spatially dividing
up resources
Niche partitioning
Due to competition, each species uses less of the niche
than they are capable of using
Example: barnacles on p. 205
Types of competition
Intraspecific competition – members of the same
species compete for food, mates, nesting sites,
space, water, etc.
Example:
Wolves fighting for meat
Alpha male will eat first
2.
Survival of the Fittest
Intraspecific competition can also be called “survival of
the fittest” and is a driving force of evolution
The individual that is best adapted to outcompete the
others will survive and pass on its traits to its offspring
Predation
Type of species interaction in which one organism
(predator) feeds on another (prey)
Predator/Prey relationships
Does the predator control the prey, or does the prey
control the predator?
Predator/Prey relationships
Many adaptations have evolved due to predator/prey
relationships
Examples of adaptations of prey:
camouflage, warning coloration, mimicry, chemical
warfare, behavior
Camouflage: Hide
Butterfly that resembles a dead leaf
Warning Coloration: Advertise that you are
not tasty
Bright colors advertise the fact that a prey is distasteful
or poisonous
Ex: bees, poison arrow frogs, coral snake
Behavior: Act tough and hang around with
your friends
Flocking and mobbing by birds – safety in numbers
Mimicry: Look like someone else
Batesian mimicry – when one
palatable species mimics
another that is harmful or
distasteful
Ex: insects mimic wasps
Right: A and B are stinging
wasps, C-E are flies that
mimic the wasps, F is a
beetle that mimics the
wasps
Mimicry
Mullerian mimicry – when two or more species look
alike and both are unpalatable, both benefit from
the reinforcement to predators to avoid the pattern
seen
Ex: Viceroy and Monarch are BOTH unpalatable
Monarch
Viceroy
Bluejay eats a monarch, then vomits,
learns not to eat them
Combination: Mimicry and behavior
Butterfly with fake eyes on wings
Urban mimicry
http://www.worth1000.com/contest.asp?contest_id=9307&display=photoshop
Urban mimicry
http://www.worth1000.com/contest.asp?contest_id=9307&display=photoshop
Predation
Examples of adaptations of
predators:
 Adaptations for capture
- pursuit
- ambush
- trap
- tools
 Adaptations for killing
- bite/claw
- suffocate
- poison
Symbiosis
 Means “living together”
 Three types….
Symbiosis
 Parasitism – the parasite lives on or in the host
 Parasite benefits, host is harmed but not usually killed
(this is different from predation where the prey is
killed)
Adult deer tick on a person
Wasp larvae living off a tomato hornworm
Parasitism
Two categories when parasite lives on/in host:
 internal (e.g., tapeworms)
 external (e.g., ticks, fleas)
Some parasites never come in contact with their hosts (e.g.,
cowbirds lay eggs in other birds’ nests and leave young to
be raised by them)
Symbiosis
 Mutualism – both species benefit from the
relationship
Benefit to clown fish: protection,
eats food caught by anemone’s
stinging cells
Benefit to anemone: clown fish
keeps anemone cleans, provides
nutrients in wastes, circulates water
Flowers and their pollinators
both benefit as pollinators eat
pollen and distribute it to other
plants
Mutualism
Pollination mutualism – animals (bees,
hummingbirds, butterflies) get food and plant gets
pollen distributed directly to the right plant
Nutritional mutualism – e.g., lichens – algae
(provides food) plus fungus (provides structure
and absorption of nutrients, water)
Gut inhabitant mutualism – bacteria in termites’ gut
or in humans’ gut help with digestion, get food
 Mutualism – lichens are made of fungus and algae,
both benefit
 Fungus: able to absorb water and nutrients from
surface material
 Algae: carries out photosynthesis to make food
(sugars)
Symbiosis
 Commensalism – one species benefits, the other is
neither hurt nor helped
Cattle egrets eat
insects in the grass
that are stirred up by
the cattle
Cattle aren’t hurt or
helped (but egrets
may pick off a few
parasites)
Commensalism
 Example: epiphytes – plants that live on other plants
but do not hurt them
Resurrection fern
Tropical orchids
Coevolution
Definition: process in which two species in a close
relationship evolve in response to each other, usually
to the benefit of one or both species
Example: plants and pollinators have adaptations that
help them in the relationship
Coevolution: Adaptations of
pollinators
 Butterfly tongue
 Hummingbird beak
Coevolution: Adaptations of plants
 The flowers of Potentilla anserina prominently
exhibit UV-meditated flower marks to aid visiting
pollinators to reach their target.