COMMUNITY ECOLO

GY:

SPECIES IN

TERACTIONS

TEXTBOOK: CHAPTE

R 20, SECTIO

N 1 (PP.

399-404)

SPECIES INTERACTIONSCommunity: all the interacting

organisms in one area (ecosystem)

Within a community, there are 5 Major Types of Species Interactions:1) Predation 3) Parasitism*2) Competition 4) Mutualism*3) Commensalism*

*Symbiosis: a close, long-term relationship between organisms of two species

PREDATIONPredation = A relationship in which an

individual of one species eats all or part of an individual of another species.

Predator: captures, kills, and consumes another organism

CarnivoresHerbivoresOminvores

Prey: organism being consumed

Predatory Adaptations include: venom, fangs, claws, speed, camouflage

PREDATOR-PREY ADAPTATIONSPrey Adaptations

include: speed, camouflage, poisons, thorns, mimicry

Mimicry: a defense in which one organism resembles another

Two types of mimicry:

AP Biology

What kind of mimicry?

Coral snake is poisonous

King snake is not

Red on yellow, poison fellow; red on black, safe from attack

2) COMPETITION Happens when two or more species use

the same resourcesCompetition results because resources

are often limited

Competition drives two key processes:1.Competitive Exclusion2.Character Displacement

*when one species is eliminated due to competition

-No two similar species can occupy the same niche = Reduced Niche Size!*Favors specialists

COMPETITIVE EXCLUSION

AP Biology

Character DisplacementThe evolution of anatomical differences to

reduce competition i.e.: Darwin’s finches evolved specialized beaks

SYMBIOSIS• Non-feeding, non-competitive

relationships• Long-term• Interspecific• Three types:1.Parasitism2.Mutualism3.Commensalism

3) PARASITISMParasitism: an interaction in which one

individual is harmed and the other benefits

Parasite: feeds on another individual (the “Host”)

4) MUTUALISMMutualism: a cooperative relationship in which both species benefit

• Many unusual behaviors such as cleaning behaviors

• Pollination is an important mutualistic relationship

5) COMMENSALISM

Commensalism: a relationship in which one species benefits and the other is not affected