Community Ecology

Ways organisms interact______________________

Between SAME and DIFFERENT kinds of organisms Compete with each other for available resources

__________________________Between DIFFERENT kinds of organisms Hunt and kill other organisms to supply their energy needs

__________________________Between SAME kind of organismsLive together and help each other

__________________________Between DIFFERENT kinds of organisms live in close association with another kind of organism

COMPETITION

PREDATION

SYMBIOSIS

COOPERATION

WHAT IS A RESOURCE?Anything needed by an organism for life____________________________________________

Examples:

________________________Nutrients, water, light, space

COMPETITION

FOOD

Organisms in an ecosystem have to compete with each other for available resources.

COMPETITIONOrganisms in an ecosystem have tocompete with each other for available resources:

SHELTER

COMPETITIONOrganisms in an ecosystem have tocompete with each other for availableresources

MATES

COMPETITIONOrganisms in an ecosystem have tocompete with each other for availableresources:

Space/territory

Prairie dogs - 5 to 35 per acreMountain lion- 1 male per 50-300 sq. mi

COMPETITIONOrganisms in an ecosystem have tocompete with each other for availableresources:

LIGHT

Ways organisms interact___________________

Between DIFFERENT kinds of organisms

Hunt and kill other organisms to supply their energy needs

PREDATION

PREDATIONOrganisms in an ecosystem that

capture and eat other organisms to supply their energy needs

Predator/Prey Adaptations

There are three strategies for fooling predators;

  1. To mimic a species that is distasteful or threatening to a predator.

  2. To camouflage, blending into the background.

  3. To use deceptive behavior whenever a predator is about to attack.

Batesian Mimicry

Batesian mimicry involves a palatable, unprotected species (the mimic) that closely resembles an unpalatable or protected species (the model). One example is this fly which looks like a bee. Birds know not to attack a bee as they will be stung. 

Mullerian Mimicry

In Mullerian mimicry, the model is not defined and several unpalatable species share warning colors or patterns to evade predation. Both models and mimics are toxic. Several species from several different orders may comprise a mimicry complex. The advantage is that the predators need only encounter one form to shun the entire complex.

Monarch Viceroy

Wasmannian Mimicry 

Wasmannian Mimicry is when the mimic resembles it's host (the model) in order to live within the same nest or structure. For example, several jumping spiders closely resemble ants. In order to get "lost in the crowd" and thus avoid predators.

Peckhamian (Aggressive) Mimicry

The predator mimics its prey to capture it. The most known example is Bird-dropping Spider. This spider hunts definite species of moths. The spider has specific glands on the abdomen which produce analogous of moths’ pheromones. Moth males allured by the pheromone fly towards the spider.

CamouflageTo look, act, smell or sound such that it blend in

with their surroundings.

Leaf Mantis

Dead Leaf Butterfly

Deceptive BehaviorTo display unusually pattern, which is weir to the predator, includes color, pattern, sound, chemical (smell), to increase their chances of

escape and survival.

Reduced Niche Size

• Due to competition and predation:– Fundamental niche - range of

conditions that an organism can potentially tolerate and the range of resources that it can potentially use

– Realized niche – part of the niche that the species actually uses due to limits set by competition and predation

Character Displacement• Evolution of differences in a

character due to competition ~ way of reducing niche overlap

Resource Partitioning• When similar species coexist, each

species may avoid competition with others by using a specific part of an available resource– Example: Robert MacArthur (1930-1972)

discovered that when more than one species of warbler is foraging within the

same tree, each species hunts for insects only in a particular section of the tree!

INTERDEPENDENCEAll living and non-living things in anecosystem are interconnected and

changingeven one thing impacts the whole

ecosystem.When one tugs at a single thing in nature, he finds it attached to the rest of the world. 

~John Muir, naturalist, Sierra Club founder

If a nutrient is in _____________OR __________________it will LIMIT the growth of thepopulation= _____________LIMITING FACTOR

SHORT SUPPLY

CYCLES SLOWLY

Kinchega National Park was drought-stricken for most of 1982 and part of 1983. Extremely low pasture biomass led to a high mortality of kangaroos. An estimated 14500 ± 1450 kangaroos died, of which 9400 were western grey kangaroos and 5100 were red kangaroos!

REMEMBER: EVERYTHING IS CONNECTED !

A decrease in the prey population means some predators will starve.Fewer predators mean prey population will increase.

Increase in prey means more food for predators.Predator population will increase until there is not enough food . . . and the cycle repeats itself.

BIOLOGY; MIller and Levine; Prentice Hall; 2006

LIMITING NUTRIENT

When an ecosystem receives a LARGE inputof limiting nutrient (ie.,fertilizer runoff) thepopulation increases dramatically = ___________

http://www.greenfacts.org/images/glossary/algae-bloom.jpg

The short supply of a limiting nutrient keeps the populationin check.

ALGAL BLOOM

Ways organisms interact

__________________Between SAME kind of organismsLive together and help each other

COOPERATION

http://www.mark-ju.net/wildlife/images/monkey03.jpg

COOPERATIONSame species live together in groups e.g. herds, packs, colonies, families, etc

Share food & childcare

responsibilitiesGroom each otherTake care of sick

COOPERATIONSame species live together in groupsEX: herds, packs, colonies, families, etc

Hunt in packsProvide protection

Ways organisms interact

__________________________Between DIFFERENT kinds of organisms Live in close association with another kind of organism

SYMBIOSIS

3 KINDS of SYMBIOSIS______________________Both organisms benefit

______________________One organism benefits;Other is neither harmed nor helped

_____________________One organism benefits;Other is harmed in some way(Endoparasites/Ectoparasites)

MUTUALISM

COMMENSALISM

PARASITISM

MUTUALISM“Good for me - Good for you”

Birds eat parasites living on the hides of giraffes and rhinos while enjoying protection from predators. Groomed animals lose their pests.

MUTUALISM “Good for me - Good for you”

Insects transfer pollen between plants as theygather nectar for food.

MUTUALISM “Good for me - Good for you”

Clown fish gets protection from enemies by hiding out in poisonous sea anemones

Sea anemone gets scraps of leftover food dropped by fish

COMMENSALISM“Good for me - Doesn’t bother you”

Pilot fish receive scraps of food dropped by shark;Shark is neither harmed nor helped

COMMENSALISM“Good for me - Doesn’t bother

you”

http://www.abyssal.com/meeks/images/hermit_crab.jpg

Hermit crabs make homes in shells abandoned by snails;Snail is not harmed by crab

CommensalismCattle egrets and Cape buffaloes in Tanzania – birds feed on small animals, such as insects and

lizards that are forced out of their hiding places when buffaloes roam

PARASITISM“Good for me - Hurts you”

Barnacles are crustaceans that attach to the surface of whales and feed on their skin and fluids; Whale is harmed

PARASITISM“Good for me - Hurts you”

Tick feeds on dog’s blood; Dog has discomfort - can get diseases/infection from bite!

•Ehrlichiosis*

•Babesiosis

•Lyme Disease

•Rocky Mountain Spotted Fever (RMSF)

•(Also – mosquitoes cause heartworm!)

PARASITISM“Good for me - Hurts you”

Tapeworms absorb food by living inside host intestine; host is harmedRover licks himself and swallows flea infested with tapeworms! Tapeworm segments end up in Rover’s stool in about three weeks time!

Parasitism

• Zebra mussels grow in thick mats on each other and other shells. Colonies can suffocate freshwater mussel beds; they are expected to cause the elimination of 8-10 species of native mussels.  Some rocky areas in Lake Erie are covered with a 10-inch deep layer of zebra mussel shells (up to 90,000 per square yard).

Patterns in communities

• Species richness: number of species in the community – simple count of species in community (decreases as one moves away from the equator)– Species-area effect: larger areas usually

contain more species than smaller areas do

• Species evenness: relative account how abundance of each species – takes into common each species is in the community

DisturbancesEpisodes that damage biological communities, at least temporarily, by destroying organisms and altering the availability of resources (storms, fires, droughts, earthquakes, floods, human activities, clear-cutting, paving, bulldozing, etc.)

Changes that communities go through is called ecological succession

PRIMARY SUCCESSION

1. Autotrophic microorganisms move in2. Lichens and mossesSoil accumulates from organic matter3. Grasses, shrubs, and trees move in4. Prevalent form of vegetation establishes self --May take hundreds to thousands of years

Community establishes self in an area that has not supported life previously, e.g., bare rock, sand dune, island formed by volcanic

eruption

PRIMARY SUCCESSION

SECONDARY SUCCESSIONCommunity establishes self where an

existing community has been cleared by a disturbance, but soil has remained in tact,

e.g., agricultureSecondary succession is usually much quicker than primary succession for the following reasons:

•There is already an existing seed bank of suitable plants in the soil. •Root systems undisturbed in the soil, stumps and other plant parts from previously existing plants can rapidly regenerate. •The fertility and structure of the soil has also already been substantially modified by previous organisms to make it more suitable for growth and colonization.

 

CLIMAX COMMUNITY

• Final stage in succession• High nutrient content in soil• Environment can support a wide array of

life forms• Many complex organisms can survive• Community composition remains

relatively stable, barring further disturbances

• Organisms exist in roughly equivalent ratios