Transcript Species interaction and Nichex

Species Interactions
Three Basic Types
1. Competition
2. Exploitation
3. Symbioses
• Mutualism
• Commensalism
• Parasitism
Competition
Any interaction between two or more
species for a resource that causes a
decrease in the population growth or
distribution of one of the species
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Competition – two species share a requirement for a
limited resource  reduces fitness of one or both species
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Intra vs Interspecific Competition
• Intraspecific competition: between members
of the same species
• Interspecific competition: between members
of different species
Reducing or Avoiding Competition
• Resource partitioning: realized niche (more about this later)
Black skimmer
seizes small fish
at water surface
Scaup and other
diving ducks feed on
mollusks, crustaceans,
and aquatic vegetation
Flamingo
feeds on
minute
organisms
in mud
Herring gull is a
tireless scavenger
Brown pelican dives for fish,
which it locates from the air
Avocet sweeps bill through
mud and surface water in
search of small crustaceans,
insects, and seeds
Louisiana heron wades into
water to seize small fish
Dowitcher probes deeply
into mud in search of
snails, marine worms,
and small crustaceans
Oystercatcher feeds on
clams, mussels, and
other shellfish into which
it pries its narrow beak
Ruddy turnstone
searches
under shells and
pebbles for small
invertebrates
Knot (a sandpiper) picks up
worms and small crustaceans
left by receding tide
Piping plover feeds
on insects and tiny
crustaceans on
sandy beaches
Exploitation - PREDATION
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Predation
• Members of predator species feed directly on
all or part of a living organism of another
species
Predator Adaptations
• Prey detection and recognition
– sensory adaptations
– distinguish prey from non-prey
• Prey capture
– passive vs. active (pursuit or ambush)
– individuals vs. cooperative
– camouflage
• Eating prey
– teeth, claws etc.
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Prey adaptations
• Avoid detection
– camouflage, mimicry
– diurnal/nocturnal
• Avoid capture
– flee
– resist
– escape
• Disrupt handling (prevent being eaten)
– struggle
– protection, toxins
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Camouflage – blending in
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Aposematic colors – warning
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Is he crazy???
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Mimicry – look like something that is
dangerous or tastes bad
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Mimicry – look like something that is dangerous
or tastes bad
Mullerian mimicry – convergence of several
unpalatable species
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Mimicry – look like something that is dangerous
or tastes bad
Batesian mimicry – palatable species mimics an
unpalatable species
model
mimics
mimic
model
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Exploitation: Herbivory
Herbivory  puts strong selective pressure on
plants
– structural adaptations for defense
– chemical adaptations for defense
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Symbiosis: Mutualists,
Commensalists and
Parasites
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• Symbiosis and symbiotic relationship are two
commonly misused terms
• Translation of symbiosis from the Greek
literally means “living together”
• Any relationship between two species of
animals is symbiosis and includes both positive
and negative interactions
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Mutualism – two species provide resources or services
to each other  enhances fitness of both species
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Rewards of Mutualism
• Food
• Protection
• Gamete or zygote dispersal (the most
common of all) Ex. pollination
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Pollination (hummingbird/bee and
flowering plants)
• animals visit flowers to collect nectar
and incidentally carry pollen from one
flower to another
• animals get food and the plants get a
pollination service
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Yucca moth and yucca
• Yucca’s only pollinator
is the yucca moth.
Hence entirely
dependent on it for
dispersal.
• Yucca moth
caterpillar’s only food
is yucca seeds.
• Yucca moth lives in
yucca and receives
shelter from plant.
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Obligatory mutualism
• Obligatory: An organism can't live
without the mutualism--either
cannot survive or cannot reproduce.
–the common pollinator systems like
bees and flowering plants
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Facultative mutualism
• Facultative: This is "take it or leave it"
for one or both partners
• While the organism benefits when
the mutualism is present, it can still
survive and reproduce without it
–ant mutualisms, such as ants
protecting plants from predation
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Commensalism – one species receives a benefit
from another species  enhances fitness of one
species; no effect on fitness of the other species
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Commensalists
• Benefit from the host
at almost no cost to
the host
• Eyelash mite and
humans
• Us and starlings or
house sparrows
• Sharks and remora
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Exploitation: Parasitism – one species benefits
at a cost to the other  enhances fitness of
parasite but reduces fitness of host
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Ecological Niche
• The role a certain species plays in an
ecosystem
• the sum total of a species’ use of the
abiotic and biotic resources in its
environment
Habitat vs. Niche
• Habitat: the environment in which a species or
organism usually lives
• Niche: the role that species plays in the
habitat – resource use, etc.
Competitive exclusion principle
No two species can occupy the same niche in the
same location in the same period of time!
“two species with similar requirements can not coexist
in the same community; one species will inevitably
harvest resources and reproduce more efficiently,
driving the other species to extinction”
Experiment that demonstrates competitive exclusion
This leads to the idea of the Ecological
Niche
Ecological Niche has two components:
Fundamental niche – set of resources a
population is theoretically capable of using
Realized niche – the resources a population
actually uses
Fundamental niche
Species A
Realized niche
F
G
B
E
Species A
C
D
Ex.
Broad and Narrow Niches
• Generalist species
• Specialist species
Number of individuals
Niches of Specialist and Generalist Species
Specialist species
with a narrow niche
Niche
separation
Generalist species
with a broad niche
Niche
breadth
Region of
niche overlap
Resource use
Which of the
NW species
you presented
on would you
classify as
generalist?
Specialist?
Types of Species
• Native species normally live and thrive in a
particular ecosystem
• Nonnative species are introduced - can be
called exotic or alien or invasive
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Nonnative Species
• Nonnative plant species are invading the
nation's parks at an alarming rate,
displacing native vegetation and
threatening the wildlife that depend on
them
• At some, such as Sleeping Bear Dunes
National Lakeshore in Michigan, as much as
23 percent of the ground is covered with
alien species, and the rate of expansion is
increasing dramatically.
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Invasive species in King County
• Many noxious weeds are so widespread in King
County that eradicating them is nearly impossible
• Weeds include: yellow-flag iris, reed canarygrass, Scotch broom,
Himalayan and evergreen blackberry, English and Irish ivy, and
purple loosestrife.
Indicator Species
• a species whose status provides
information on the overall condition of
the ecosystem and of other species in
that ecosystem
• reflect the quality and changes in
environmental conditions as well as
aspects of community composition
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Examples of Indicator Species
•
•
•
•
•
Spotted owls – old growth forests
River otters – clean rivers
Frogs – pollutants transfer easily through skin
Corals – marine environments
What is an indicator species? Pika video
Common Air Pollution Indicator
• Lichen: Symbiotic relationship between Algae
& fungi
• 3 types – their presence indicates various
levels of pollutants.
The most sensitive lichens are shrubby and leafy while the most
tolerant lichens are all crusty in appearance. (http://www.airquality.org.uk/19.php)
“Why did the fungi & algae get together?”
• Crustose
• Foliose
• Fruticose
Do Indicator species tend to be
considered generalists or specialists?
Keystone Species
• a species on which the persistence of a large number of
other species in the ecosystem depends.
• If a keystone species is removed from a system
– the species it supported will also disappear
– other dependent species will also disappear
• Examples
– top carnivores that keep prey in check
– large herbivores that shape the habitat in which other species live
– important plants that support particular insect species that are prey for
birds
– bats that disperse the seeds of plants
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Keystone cont.
• exerts an impact on its community that is both
strong and disproportionate to its abundance
The sea star Pisaster ochraceus, the
original keystone species, feeds
preferentially on mussels on northeast
Pacific rocky shores. By doing so, the
predatory sea star prevents mussels from
taking over the entire shore and allows
less competitive species to persist, thus
enhancing local species diversity.
(Source: Multi-Agency Rocky Intertidal
Network)
The sea otter Enhydra lutris can be
considered a keystone predator
because its voracious feeding on
herbivorous sea urchins allows kelps to
flourish along the rocky coast, along
with an entire ecosystem associated
with these large marine plants. Photo
by Matt Knoth. (Source: Wikimedia
Commons)
Keystone species vs. Indicator
• https://www.youtube.com/watch?v=xRfdDE6s
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