Community Interactions

Relationships Between Organisms

• Predator-Prey Relationships– Predators can affect the size of prey

populations in a community and determine the places prey can live and feed

• Ex: Fox and rabbit populations

• Herbivore-Plant Relationships– Herbivores can affect both the size and

distribution of plant populations in a community and determine the places certain plants can survive and grow

• Ex: White tailed deer and food plants

Keystone Species:– A species of great importance to a community– If it’s population changes it can cause

dramatic changes to structure of community

– Ex: • Sea Otters off Pacific Coast of North America

– Links to Sea urchins, kelp and many other species– http://www.youtube.com/watch?v=eYpM-qDNKzs&safe=

active

• Beavers (a keystone species)

http://www.youtube.com/watch?v=kZVbKwDmr-o&safe=active

Symbiotic Relationships

• Organisms live in close association with each other and at least one benefits.

• Relationships that help one or both species to survive

• Symbiotic Relationships:• http://www.youtube.com/watch?v=nRkWz

LzCi2U&safe=active

Mutualism:– Both species benefit

Ex: • Clown Fish and Sea Anemone• Ants and aphids• “Cleaning Stations” (Rhino and “Tick Bird”)

• Ex: Protozoa in digestive tracts of termites– Termites have cellulose digesting microorganisms in

their digestive tract– Provide food and a place to live– Termites could not get nutrients from wood without them.

http://www.youtube.com/watch?v=CiBAq2a6qjQ&safe=active

• Ant and Butterfly Symbiosis:• http://video.nationalgeographic.com/video/

animals/bugs-animals/ants-and-termites/ant_caterpillarsymbiosis/

• Goby and Shrimp • http://www.youtube.com/watch?v=dKuWlB

jUFo8&safe=active

Commensalism: • One species benefits, the other species is

neither harmed nor benefitted– Ex: Remora and pilot fish and shark

– Eats scraps from sharks meal

– Barnacle and whale– Whale travels about, allowing them to get a constantly

new supply of food

Parasitism:• One organism benefits and the

other is harmed• Generally parasites weaken,

but do not kill the host

– EX: – Tapeworms in digestive tract– Mistletoe plant: sends roots into

host plant and absorbs water, minerals and nutrients

– Cowbird (brood parasite)– Leeches, Ticks, Fleas, Lice (feed

on blood and skin of animals)

• Check out this Crazy Fungal Parasite!• Cordyceps:

http://www.youtube.com/watch?v=XuKjBIBBAL8&safe=active

• Body Invaders:• http://www.youtube.com/watch?v=vMG-LWyNcAs&safe=

active

• Symbiotic Relationships:• http://www.youtube.com/watch?v=zSmL2F

1t81Q&safe=active

Ecological Succession

Succession in Communities

• Changes that take place to communities over time (especially after disturbances).

• Living organisms alter their environment making it more suitable for some, less suitable for others

• Original organisms slowly replaced by others until climax community is reached

• Takes decades or even centuries to develop

Islands of Hawaii

• How did they become a tropical paradise?

• Started off as volcanic rock.

• Colonization of new sites (lifeless areas)• Bare rock, new volcanic islands, sand,

stream bank (no organic material present)

– Slow process– Begins with soil formation

Primary Succession:

Soil Formation:• Starts with rocks

• Erosion by wind/rain causes pieces to break off

• Freezing/thawing of water causes cracks to form

Pioneer Organisms: first organisms to colonize barren areas

Ex: Lichens: (mutualistic symbiosis between fungus/algae)– Cling to rocks, secrete acids that help break down rock– When they die, they add layer of organic material that

starts soil formation

http://teachertube.com/viewVideo.php?video_id=182733

• Plants like mosses now can grow in the thin layer of soil

• When they die out the soil layer gets thicker and thicker eventually allowing plants with deeper and deeper roots to thrive.

• Eventually a climax community develops

Primary Succession

How Long Does it Take?

Note: Animal life will also change with the succession of plantsEx: grass eaters – shrub dwellers – tree livers

Climax Community: • Community at the end of line of succession that

is mature and stable

– Described in terms of dominant plant forms– Type of climax community depends on the physical

factors in environment

• Ex: – Good soil/good rainfall = forest community– Good soil/less rainfall = grassland community

– Climax Communities:– http://www.youtube.com/watch?v=iZA5yfrzLV8&safe=active

• Examples of Climax Communities:

• Sphagnum Bog: shallow lake/pond, peat moss• Mangrove Swamp: muddy tidal flat, mangrove trees• Pine Barrens: sandy peat soil, pine trees

• Occurs in an area where the climax community has been destroyed

• However, SOIL IS STILL THERE!

• Occurs at a faster rate, soil is already present.

– Ex: – Forest fire, flood, volcanic explosion, human development

• Succession after Fire:• http://www.youtube.com/watch?v=C2ZRe_kIRdA&safe=active

Secondary Succession

• Pine Barrens Fire

Note: some species require catastrophe to reproduce

Ex: Certain pine cones will only release seeds if heated by fire

Secondary Succession Can Happen Here

Soil is Established

Succession in Lakes and Ponds• Sediment, fallen leaves, debris gradually accumulate

on the lake bottom• Plants take root in the shallower water along edge • Pond eventually becomes a marsh• Eventually fills up becoming dry land

• Succession Summary:• http://education-portal.com/academy/

lesson/ecological-succession-from-pioneer-to-climax-communities.html

Biomes of the Earth

Biomes: large geographical regionscharacterized by a particular type of climaxcommunity

Have similar: temperature range annual precipitation sun exposuretype of soil type of plants and animals

• Temperature Differences: – Not all parts of the earth get the same amount of

sunlight– Five times stronger at equator than at the poles– Seasons change due to tilt of Earth’s axis and

amount of sunlight over course of the day

• Topography: – Mountain ranges can affect rainfall patterns

from one side of mountain to another– Can often see changes in plant communities

with increasing altitude as temperature changes

Types of Terrestrial Biomes

Tundra

• Characteristics: – Low average temp, short growing season– Long cold winters where ground is completely frozen – Only thin top layer thaws in summer, rest is permafrost– Average precipitation 10-12cm per year (mostly snow)

http://education-portal.com/academy/lesson/biomes-tundra-taiga-temperate-grassland-and-coastlines.html

Tundra• Vegetation:

– lichens, moss, grasses, sedges, shrubs– Almost no trees due to permafrost and short growing

season– Nutrient poor soil due to slow rate of decomposition

(nutrients recycled slowly)

Tundra• Animals:

– Reindeer, mush oxen, caribou, wolves, arctic hares, arctic foxes, lemmings, snowy owls

– During warm season: a lot of insects like flies and mosquitoes bring birds, ducks, geese to nest and breed in safety because of relative absence of certain predators

Taiga

• Characteristics:• Cold severe winters, short mild summers• Ground thaws completely in summer (no

permafrost), so can support tree growth• Precipitation 35-40cm a year with a lot of fog

http://dsc.discovery.com/tv-shows/other-shows/videos/assignment-discovery-shorts-iii-biomes-taiga.htm

Taiga

• Vegetation: • Mostly coniferous pines, firs, spruce

(evergreens)• Soil often acidic due to pine needles

Taiga

• Animals: • Moose, wolves, bears, lynx, deer, elk,

wolverines, martens, snow shoe hares, porcupines, rodents, birds, insects

Deserts• Characteristics:• Driest biome• Sandy soil, nutrient poor• Rainfall less than 25 cm per year (arid)• Temp. varies widely during day

Deserts• Vegetation: • Special adaptations

to conserve water

• Widespread shallow roots to get maximum water when available

• Cactus, yucca, mesquite trees, sagebrush, creosote bushes

Deserts• Animals: • Many active at night,

sleep during day due to heat

• Adaptations to conserve water and radiate excess heat

• Fennec, snakes, lizards, spiders, scorpions, foxes, coyotes, hawks, owls, kangaroo rat

http://www.youtube.com/watch?v=7Ifk9IJl0A0&safe=active

Temperate Deciduous Forests• Characteristics:• Cold winters, hot and humid summers• Growing season about 6 months of year• Rainfall 75-150cm per year

Temperate Deciduous Forests• Vegetation: • Soil: thick top layer of humus• Mostly deciduous trees• Period of plant dormancy

during winter (lose leaves)• Oak, maple, hickory, beech,

chestnut, birch, shrubs, herbaceous plants, ferns and mosses

Temperate Deciduous Forests• Animals:• Many hibernate during

winter • Wolf, fox, bobcat, deer,

raccoon, squirrel, chipmunk, rabbits, salamanders, birds (many migrate during winter)

Grasslands• Characteristics:• Prairies, steppes, pampas,

savannah • Occurs in both temperate

and tropical climates• Rainfalls is 25-75cm per

year (usually with dry season)

• Soil deep and rich, (good farmland)

•http://www.youtube.com/watch?v=msdY-JJilzM&safe=active

Grasslands

• Vegetation: • Many species of grass (rye, oat, wheat)

and wild flowers• Where more water present, shrubs and

some trees may develop.

Grasslands• Animals:

• North America: coyote,rattlesnake, prairie dog, jack rabbit, bison, pheasant, prairie chicken, hawk, owl

• Africa: zebras, giraffes, gazelles, lions, elephants

Tropical Rain Forests

• Characteristics:• Most biologically

diverse ecosystem• Greatest number of

species per unit area• Uniform warm wet

climate through year • Constant rainfall 200-

400cm per year

Tropical Rain Forest

• Vegetation:• Broad leaved plants, most

do not lose leaves• Little light hits lower canopy • Only shade tolerant trees,

vines and shrubs, grow below tall trees

• Little organic material in soil (poor farmland)

• Organic materials decay quickly and recycle back into living plants

Tropical Rain Forest

• Animals: • Wide variety,

many are adapted to live at a particular level of the canopy

• Monkeys, bats, parrots, snakes, lizards, tapirs, insects

Aquatic Ecosystems• Major Abiotic Factors:

– Water depth:• Photic Zone: sunlight can reach

it, photosynthesis can occur

• Aphotic Zone: deeper water, photosynthesis cannot occur

– Amount of dissolve gasses and nutrients

• Oxygen and Carbon Dioxide, Nitrogen, Phosphorus

Aquatic Ecosystems• Marine Biomes (saltwater oceans)

– Largest most stable biome (70% of earths surface)

– Most photosynthesis on Earth is done here by algae near ocean surface

– Oceans absorbs and hold large quantities of heat and help to regulate Earth’s temp.

– Temperature very stable, changes less during the day than on land

• Marine Animals:• Ocean floor (benthic life): Sponges, corals,

barnacles, anemones, starfish, clams, snails, crabs

• Free Swimming: squid, fish, turtles, seals, whales

• Plankton: float near surface and are carried by currents

• Phytoplankton: Photosynthetic producers• Zooplankton: Consumers

• Form basis of food web for whole marine ecosystem

• Zones of the Oceans

• Intertidal Zone:– High tide: submerged– Low Tide: exposed to air & sunlight

• Coastal Ocean (Littoral Zone) – Shallow, slopes to open ocean– Contains nutrients carried into

ocean by rivers and streams

• Open Ocean – Deep water, photic & aphotic zones – Most photosynthesis happens here

• Deep Ocean– No sunlight, under high pressures– Food webs based on dead

organisms that fall from above or on chemosynthetic organisms

• Estuaries: – Saltwater meets

freshwater (where river meets the sea)

– Excellent nurseries to raise young aquatic wildlife (offers protection)

• Freshwater Biomes– Ponds, lakes,

streams, rivers, wetlands (swamps and bogs)

– Provide most land animals with fresh drinking water

– Many be nutrient rich or poor depending on amount of sediment