Species interactions such as competition, predation, parasitism, and mutualism affect population sizes and resource use. Competition is the most common interaction where two species cannot coexist using the same limited resources, often resolved by migration, changing diets/behavior, population drops, or extinction. Predation influences species distributions and regulates populations, while coevolution leads to an arms race between predator techniques and prey defenses. Parasitism and mutualism also impact biodiversity through host regulation or reciprocal benefits between species.

1. Species InteractionsSpecies Interactions
By Mr. “I got worms” ChapmanBy Mr. “I got worms” Chapman

2. Concept to UnderstandConcept to Understand
• Species interactions affect the resource
use and population sizes of the species in
an ecosystem.

3. Species InteractionsSpecies Interactions
• Symbiosis – interactions between species.
• Ex. Predation, parasitism, competition,
mutualism, and commensalism.

4. Interspecific CompetitionInterspecific Competition
• 1. Competition – the most common interaction
between species
• No two species can share vital limited resources
for long (no same niche).

5. Interspecific CompetitionInterspecific Competition
• Resolved by:
– Migration – move somewhere else
– Shift in feeding habits or behavior – eat something else
– Population drop – fewer individuals
– Extinction – die out

6. Intense competition leads toIntense competition leads to resource partitioning –resource partitioning –
each species becomes more specializedeach species becomes more specialized
Cape May
Warbler
Blakburnian
Warbler
Black-throated
Green Warbler
Yellow-rumped
Warbler
Bay-breasted
Warbler
Fig. 5-2, p. 81

7. InteractionsInteractions
• Competition – when 2 or more species
use the same limited resources.
– Competitive Exclusion

8. PredationPredation
• Predation – one individual, the predator,
captures, kills, and consumes another
individual, the prey.

9. PredationPredation
• Predation influences where and how
species live and is an effective way to
regulate population size.

10. Predator TechniquesPredator Techniques
• 1. Ambush
(lions)
• 2.
Camouflage
(praying
mantis)
• 3. Chemical
warfare
(poisonous
snakes)

11. Prey TechniquesPrey Techniques
• 1. Evasion (birds – fly away)
• 2. Alertness – highly developed senses (fly –
compound eye)

12. Prey TechniquePrey Technique
• Mimicry – a type of defense where
harmless species resemble a poisonous
species.

13. Prey TechniquesPrey Techniques
• Protection – shells, bark, spines, thorns (turtle,
porcupines)
• Camouflage (leaf insects)

14. Prey TechniquesPrey Techniques
• Warning coloration (poisonous dart frogs,
taste bad)
• Behavioral strategies – puffing up
(blowfish)

15. CoevolutionCoevolution
• Predator and prey Relationship
• Intense natural selection pressure on each other
• Each can evolve to counter the advantageous traits
the other has developed called Coevolution.
– Bats and moths

16. ParasitismParasitism
• Parasitism – one individual, known as
parasite, feeds on another individual,
known as the host.
• Parasites promote biodiversity – help keep
populations of hosts in check

18. InteractionsInteractions
• Mutualism – is a cooperative relationship
where both species benefit.
–Ex. Clown fish and anemone

19. MutualismMutualism
• Both species benefit
– provides food, shelter, or some other resource
• Nutrition and protection
• Gut inhabitant mutualism

20. InteractionsInteractions
• Commensalism – is interaction where
one species benefits and the other is not
affected.
–Movement of buffalo and birds eat
insects and lizards

21. CommensalismCommensalism
• Benefits one species with little impact on
other

22. Animation: How SpeciesAnimation: How Species
InteractInteract
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ANIMATION