Species Interaction
Questions for Today:
• What are the five ways species interact with
each other?
• How does competition effect species
interactions?
• Describe Predator-Prey Relationships and how
those relationships creates a coevolution event?
• What are three types of symbioses found in
nature?
Species Interact in Five Ways
• There are five basic types of species
interactions:
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Interspecific Competition
Predation
Parasitism
Mutualism
Commensalism
• These interactions help influence survival
techniques which make them agents of Natural
Selection.
Competition
• The most common interaction between species
is competition.
– One species will eventually become more efficient in
acquiring resources and food.
• When two species compete for food in the same
niche, their niches overlap
– Remember only one species can occupy a niche at a
time.
• Competitive exclusion principle.
• What are the possible responses to niche
overlap?
Predation
• All organisms need food to survive
– Plants make their own
– All other must eat
• Predation is the interaction between a
feeder (predator) and what it eats (prey).
• Herbivores, Carnivores and Omnivores
are all predators.
Predators
• Predator have two primary ways of capturing
prey.
– Pursuit and ambush
• Most predator have developed adaptations in
either of these two areas.
– Cheetahs - speed
– Snowy Owl – camouflage
• Some predators use chemical warfare to
paralyze it’s enemy.
Prey
• In answer to the Predator, many prey species
have developed ways to defend themselves.
– Physical barriers and strengths
• Spines, shells, thick bark
• Faster escape and strong senses
– Camouflage
• Cuttlefish
– Chemical Warfare
• Poisonous to eat or create poison that they excrete when
aggravated.
• Taste Bad
Prey
• Good rule of thumb
– If it is small and strikingly beautiful, it’s
poisonous
– If it is strikingly beautiful and easy to catch,
it’s DEADLY
• Other prey species use behavioral
strategies to evade predators.
– Mimicry
(a) Span worm
(c) Bombardier beetle
(e) Poison dart frog
(g) Hind wings of Io moth
resemble eyes of a much
larger animal.
(b) Wandering leaf insect
(d) Foul-tasting monarch butterfly
(f) Viceroy butterfly mimics
monarch butterfly
(h) When touched,
snake caterpillar changes
shape to look like head of snake.
Fig. 5-2, p. 103
Benefit of Predator-Prey
Relationships
• Predation plays a major role in Natural
Selection
– Predators weed out the weak, sick, and
dying species.
– Increases biodiversity
• Help keep grazing animals down and
preserve the balance of an ecosystem.
Coevolution and Pred. v. Prey
Relationships
• Coevolution is when two organisms
evolve due to pressures exerted from
each other.
– It’s like an evolutionary arms race
• Constant struggle for survival create
harder prey to catch and stronger
predators to catch them.
Symbiosis
• Symbiosis are when two species live
together in some form.
• Three Types of Sybiosis:
– Parasitism
– Commensalism
– Mutualism
Parasitism
• Parasitism occurs when one species (the
parasite) feeds on the body of, or the
energy used by, another organism (the
host), usually by living on or in the host.
• Common Characteristics of Parasites:
– Smaller than the host
– Rarely Kill the Host
– Live directly on or in the Host
Parasitism: Tree with Parasitic
Mistletoe, Trout with Blood-Sucking
Sea Lampreys
Commensalism
• Commensalism is when two species
interact where one species benefits and
the other is not harmed or benefits
lightly.
Commensalism: Bromiliad Roots on Tree Trunk
Without Harming Tree
Mutualism
• An Interaction where two species benefit
from living together.
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Nutrition
Protection
Hygiene
Health
Mutualism: Oxpeckers Clean Rhinoceros;
Anemones Protect and Feed Clownfish
Video: Otter feeding