COMMUNITY ECOLOGY

YOU MUST KNOW…• THE DIFFERENCE BETWEEN A

FUNDAMENTAL NICHE AND A REALIZED NICHE

• THE ROLE OF COMPETITIVE EXCLUSION IN INTERSPECIFIC COMPETITION

• THE SYMBIOTIC RELATIONSHIPS OF PARASITISM, MUTUALISM, AND COMMENSALISM

YOU MUST KNOW…• THE IMPACT OF KEYSTONE

SPECIES ON COMMUNITY STRUCTURE

• THE DIFFERENCE BETWEEN PRIMARY AND SECONDARY SUCCESSION

CONCEPT 54.1• COMMUNITY INTERACTIONS ARE

CLASSIFIED BY WHETHER THEY HELP, HARM, OR HAVE NO EFFECT ON THE SPECIES INVOLVED

• COMMUNITY – A GROUP OF POPULATONS OF DIFFERENT SPECIES LIVING CLOSE ENOUGH TO INTERACT

• INTERSPECIFIC INTERACTIONS – MAY BE POSITIVE FOR ONE SPECIES, NEGATIVE, OR NEUTRAL AND INCLUDE COMPETITION, PREDATION, AND SYMBIOSES

• INTERSPECIFIC – BETWEEN TWO DIFFERENT GROUPS

• INTRASPECIFIC – COMPETITION WITHIN THE SAME SPECIES

• EX – 2 MALES FIGHTING OVER THE SAME

TERRITORY

INTERSPECIFIC COMPETITIONS• OCCURS WHEN RESOURCES ARE

IN SHORT SUPPLY• A -/- INTERACTION BETWEEN THE

SPECIES INVOLVED• 2 CONCEPTS• COMPETITIVE EXCLUSION

PRINCIPLE• NICHES

COMPETITIVE EXCLUSION PRINCIPLE

• WHEN TWO SPECIES ARE VYING FOR A RESOURCE, EVENTUALLY THE ONE WITH

THE SLIGHT REPRODUCTIVE ADVANTAGE WILL ELIMINATE THE OTHER

NICHES• THE NICHE OF A SPECIES IS

DETERMINED BY THE HABITAT IN WHICH IT LIVES

• THE ECOLOGICAL NICHE IS THE SUM OF THE HABITAT REQUIREMENTS (BIOTIC & ABIOTIC RESOURCES) THAT THE SPECIES USES IN ITS ENVT THAT ALLOW A SPECIES TO PERSIST AND PRODUCE OFFSPRING

• FUNDAMENTAL NICHE – THE NICHE POTENTIALLY OCCUPIED BY THE SPECIES

• REALIZED NICHE – A PORTION OF THE FUNDAMENTAL NICHE THE SPECIES ACTUALLY OCCUPIES

PREDATION• A +/-

INTERACTION BETWEEN TWO SPECIES WHERE THE PREDATOR EATS THE PREY

SYMBIOSIS• OCCURS WHEN INDIVIDUALS LIVE IN

DIRECT CONTACT WITH ONE ANOTHER

• PARASITISM – A +/- INTERACTION• MUTUALISM – A +/+ INTERACTION• COMMENSALISM – BENEFITS ONE

SPECIES BUT NEITHER HARMS NOR HELPS THE OTHER SPECIES (+/o)

• EX – FERN GROWING IN THE SHADE OF ANOTHER PLANT

51-1, 51-2 - DEFENSES• CRYPTIC COLORATION - CAMOUFLAGE• APOSEMATIC OR WARNING COLORATION

– A POISONOUS ANIMAL IS BRIGHTLY COLORED AS A WARNING TO OTHER ANIMALS

• BATESIAN MIMICRY – A HARMLESS SPECIES HAS EVOLVED TO MIMIC THE COLORATION OF AN UNPALATABLE OR HARMFUL SPECIES

• HERBIVORY – A +/- INTERACTION WHERE AN HERBIVORE EATS PART OF A PLANT OR ALGA, IT’S ADVANTAGEOUS FOR AN ANIMAL TO BE ABLE TO DISTINGUISH TOXIC FROM NONTOXIC PLANTS

TYPES OF ANIMAL LEARNING

• ASSOCIATIVE LEARNING – ANIMALS TAKE ONE STIMULUS AND ASSOCIATE IT WITH ANOTHER

• CLASSICAL CONDITIONING (a type of associative learning) – ONE STIMULUS IS SUBSTITUTED FOR ANOTHER TO EVOKE THE SAME RESPONSE (PAVLOV)

• FIXED-ACTION PATTERN – INNATE, PREPROGRAMMED RESPONSE TO A STIMULUS

• HABITUATION – THE LOSS OF RESPONSIVENESS TO UNIMPORTANT STIMULI

• IMPRINTING – INNATE BEHAVIOR THAT IS LEARNED DURING A CRITICAL PERIOD EARLY IN LIFE. ONCE MADE, IT IS IRREVERSIBLE.

• INSIGHT LEARNING – THE ABILITY TO DO SOMETHING RIGHT THE FIRST TIME WITH NO PRIOR EXPERIENCE. IT REQUIRES REASONING ABILITY.

• OBSERVATIONAL LEARNING – TO LEARN HOW TO DO SOMETHING BY WATCHING ANOTHER INDIVIDUAL DO IT FIRST

• OPERANT CONDITIONING – BASED ON TRIAL AND ERROR. THE ASSOCIATION IS MADE BETWEEN THE ANIMAL’S OWN BEHAVIOR AND A RESPONSE.

CONCEPT 54.2• DOMINANT AND KEYSTONE

SPECIES EXERT STRONG CONTROLS ON COMMUNITY STRUCTURE

• SPECIES DIVERSITY – MEASURES THE NUMBER OF DIFFERENT SPECIES AND THE RELATIVE ABUNDANCE OF EACH SPECIES

• TROPHIC STRUCTURE – REFERS TO THE FEEDING RELATIONSHIPS

• FOOD CHAIN – THE TRANSFER OF FOOD ENERGY FROM PLANTS THROUGH HERBIVORE THROUGH CARNIVORES THROUGH DECOMPOSERS

• FOOD WEB – CONSISTS OF TWO OR MORE FOOD CHAINS LINKED TOGETHER

• DOMINANT SPECIES – HAVE THE HIGHEST BIOMASS (THE SUM WEIGHT OF ALL THE MEMBERS OF A POPULATION)

• KEYSTONE SPECIES – EXERT CONTROL ON COMMUNITY STRUCTURE BY THEIR IMPORTANT ECOLOGICAL NICHES

CONCEPT 54.3• DISTURBANCE INFLUENCES

SPECIES DIVERSITY AND COMPOSITION

DISTURBANCE• STORM, FIRE, HUMAN ACTIVITY,

ETC. THAT CHANGES A COMMUNITY BY REMOVING ORGANISMS OR CHANGING RESOURCE AVAILABILITY

• NOT NECESSARILY

BAD

INTERMEDIATE DISTURBANCE HYPOTHESIS

• STATES THAT MODERATE LEVELS OF DISTURBANCE CREATE CONDITIONS THAT FOSTER GREATER SPECIES DIVERSITY THAN LOW OR HIGH LEVELS OF DISTURBANCE

ECOLOGICAL SUCCESSION

• THE TRANSITIONS IN SPECIES COMPOSITION IN A CERTAIN AREA OVER ECOLOGICAL TIME

• PRIMARY SUCCESSION – PLANTS AND ANIMALS GRADUALLY INVADE A REGION THAT WAS VIRTUALLY LIFELESS WHERE SOIL HAS NOT YET FORMED

• EX – GRADUAL COLONIZATION OF A NEWLY FORMED VOLCANIC ISLAND

• SECONDARY SUCCESSION – OCCURS WHEN AN EXISTING COMMUNITY HAS BEEN CLEARED BY A DISTURBANCE THAT LEAVES THE SOIL INTACT

CONCEPT 54.4• BIOGEOGRAPHIC FACTORS

AFFECT COMMUNITY BIODIVERSITY

• LATITUDE OF THE COMMUNITY – PLANT AND ANIMAL LIFE IS GENERALLY MORE ABUNDANT IN TROPICS

• AREA OF THE COMMUNITY – IF ALL OTHER FACTORS ARE HELD EQUAL, THE LARGER THE GEOGRAPHIC AREA OF A COMMUNITY IS, THE MORE SPECIES IT HAS

ISLAND BIOGEOGRAPHY• RATES OF IMMIGRATION AND EXTINCTION

ARE INFLUENCED BY THE SIZE OF THE ISLAND AND THE DISTANCE OF THE ISLAND FROM THE MAINLAND ( THE GREATER THE SIZES OF THE ISLAND, THE HIGHER THE IMMIGRATION RATES AND LOWER THE RATES OF EXTINCTION)

• AS DISTANCE FROM THE MAINLAND INCREASES, THE RATE OF IMMIGRATION FALLS AND EXTINCTION RATES INCREASE