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 organisms Live 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.

COMPETITION Organisms in an ecosystem have to compete with each other for available resources: SHELTER

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

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

Space/territory

Prairie dogs - 5 to 35 per acre

Mountain lion- 1 male per 50-300 sq. mi

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

LIGHT

Ways organisms interact ___________________

Between DIFFERENT kinds of organisms

Hunt and kill other organisms to supply their energy needs

PREDATION

PREDATION Organisms 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.

Camouflage To look, act, smell or sound such that it blend in with

their surroundings.

Leaf Mantis

Dead Leaf Butterfly

Deceptive Behavior To 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!

INTERDEPENDENCE All living and non-living things in an

ecosystem are interconnected and changing

even 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 the population = _____________ 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 input

of limiting nutrient (ie.,fertilizer runoff) the

population increases dramatically = ___________

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

The short supply of a limiting nutrient keeps the population in check.

ALGAL BLOOM

Ways organisms interact __________________ Between SAME kind of organisms Live together and help each other

COOPERATION

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

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

Share food & childcare

responsibilities Groom each other Take care of sick

COOPERATION Same species live together in groups EX: herds, packs, colonies, families, etc

Hunt in packs Provide 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 they gather 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

Commensalism

Cattle 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 harmed

Rover 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

Disturbances Episodes 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 in 2. Lichens and mosses Soil accumulates from organic matter 3. Grasses, shrubs, and trees move in 4. 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 SUCCESSION Community establishes self where an existing

community has been cleared by a disturbance, but soil has remained in tact, e.g., agriculture

Secondary 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