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=eYpMqDNKzs&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-andtermites/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=a
ctive
• Body Invaders:
• http://www.youtube.com/watch?v=vMGLWyNcAs&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.
Primary Succession:
• Colonization of new sites (lifeless areas)
• Bare rock, new volcanic islands, sand,
stream bank (no organic material present)
– Slow process
– Begins with soil formation
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 plants
Ex: 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
Secondary Succession
• 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
• 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://educationportal.com/academy/lesson/ecologicalsuccession-from-pioneer-to-climaxcommunities.html
Biomes of the Earth
Biomes: large geographical regions
characterized by a particular type of climax
community
Have similar:
temperature range
annual precipitation
sun exposure
type 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
http://educationportal.com/academy/lesson/biomestundra-taiga-temperate-grasslandand-coastlines.html
• 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)
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
http://dsc.discovery.com/tv-shows/other-shows/videos/assignment-discovery-shorts-iii-biomes-taiga.htm
• 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
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 200400cm 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