Download Keystone species: Ecology

KEYSTONE SPECIES: ECOLOGY
DEFINITION:
• A SPECIES ON WHICH OTHER SPECIES IN AN ECOSYSTEM LARGELY DEPEND, SUCH THAT IF IT
WERE REMOVED THE ECOSYSTEM WOULD CHANGE DRASTICALLY.
• EXAMPLES: SEA OTTER, BEAVER, GREY WOLF, ACORN BANKSIA
• TYPES: PREDATORS, MUTUALISTS, ENGINEERS
• NOT DOMINANT SPECIES (DOMINANT SPECIES IS ALL OF ONE SPECIES WEIGHED TOGETHER
AND EQUAL THE MOST OUT OF ALL SPECIES)
KEYSTONE PREDATOR
• EXAMPLE SEA OTTER:
• DOES NOT HAVE TO BE THE APEX PREDATOR, ORCA’S
PREY ON SEA OTTERS
• SEA OTTERS EAT SEA URCHINS, SEA URCHINS EAT KELP
HOLDFASTS, SO SEA OTTERS PROTECT THE KELP
FORESTS FROM DAMAGE.
• THE KELP PROVIDES THE MAJOR BACKBONE OF THE
ECOSYSTEM (PROTECTION, PRIMARY FOOD PRODUCER)
SO IT IS POSSIBLY THE DOMINANT SPECIES.
• IF THE SEA OTTER IS NOT PRESENT THE SEA URCHINS
EAT ALL THE KELP AND TOTALLY WIPE OUT THE
ECOSYSTEM
• THIS IS WHAT MAKES THE SEA OTTER THE KEYSTONE
SPECIES IN THIS CASE
With Sea Otter
Without
KEYSTONE PREDATOR
• EXAMPLE: JAGUAR
• THE JAGUAR, WHOSE NUMBERS IN CENTRAL AND
SOUTH AMERICA HAVE BEEN CLASSIFIED AS NEAR
THREATENED, ACTS AS A KEYSTONE PREDATOR BY ITS
WIDELY VARIED DIET, HELPING TO BALANCE THE
MAMMALIAN JUNGLE ECOSYSTEM WITH ITS
CONSUMPTION OF 87 DIFFERENT SPECIES OF PREY.
• ANY MAMMAL THAT BEGINS TO THRIVE BECOMES
THE EASY MEAL FOR THE JAGUAR AND AS SUCH ITS
NUMBERS DECREASE. THIS KEEPS SPECIES DIVERSITY
HIGH.
KEYSTONE MUTUALISTS
• KEYSTONE MUTUALISTS ARE ORGANISMS THAT
PARTICIPATE IN MUTUALLY BENEFICIAL INTERACTIONS, THE
LOSS OF WHICH WOULD HAVE A PROFOUND IMPACT
UPON THE ECOSYSTEM AS A WHOLE.
• EXAMPLE: BANKSIA PRIONOTES (ACORN BANKSIA)
• AT ONE TIME OF YEAR THE ACORN BANKSIA IS THE
SOLE FOOD SOURCE FOR HONEYEATERS
• HONEYEATERS ARE THE PRIMARY POLLINATION
FACILITATORS IN THE REGION
• WITHOUT THE ACORN BANKSIA THE POLLINATORS
WILL DIE AND AS SUCH THE POLLINATING PLANTS OF
THE AREA WILL DIE OUT TOTALLY CHANGING THE
ECOSYSTEM.
With Acorn Banksia
Without
KEYSTONE MUTUALIST
• EXAMPLE: CASSOWARY
• FRUGIFORE (FRUIT EATER)
• SPREADS FRUIT SEEDS ALL OVER
RAINFOREST
• WITHOUT IT PLANTS CANNOT SPREAD
OUT AND COMPETITION INCREASES
• IF THIS IS THE CASE SPECIES DIVERSITY
WILL DRAMATICALLY DECREASE
• EXAMPLE: PRAIRIE DOG.
KEYSTONE ENGINEER
• PRAIRIE DOG BURROWS PROVIDE THE NESTING AREAS
FOR MOUNTAIN PLOVERS AND BURROWING OWLS.
• PRAIRIE DOG TUNNEL SYSTEMS ALSO HELP CHANNEL
RAINWATER INTO THE WATER TABLE TO PREVENT
RUNOFF AND EROSION, AND CAN ALSO SERVE TO
CHANGE THE COMPOSITION OF THE SOIL IN A REGION
BY INCREASING AERATION AND REVERSING SOIL
COMPACTION THAT CAN BE A RESULT OF CATTLE
GRAZING.
• PRAIRIE DOGS ALSO TRIM THE VEGETATION AROUND
THEIR COLONIES, PERHAPS TO REMOVE ANY COVER
FOR PREDATORS. EVEN GRAZING SPECIES SUCH AS
PLAINS BISON, PRONGHORN, AND MULE DEER HAVE
SHOWN A PROCLIVITY FOR GRAZING ON THE SAME
LAND USED BY PRAIRIE DOGS. IT IS BELIEVED THAT
THEY PREFER THE VEGETATIVE CONDITIONS AFTER
PRAIRIE DOGS HAVE FORAGED THROUGH THE AREA.
KEYSTONE ENGINEER
• EXAMPLE: AMERICAN BEAVER
• TRANSFORMS ITS TERRITORY FROM A STREAM TO A
POND OR SWAMP
• AFFECT THE ENVIRONMENT FIRST ALTERING THE EDGES
OF RIPARIAN AREAS BY CUTTING DOWN OLDER TREES
TO USE FOR THEIR DAMS, ALLOWING YOUNGER TREES TO
TAKE THEIR PLACE
• THESE DAMS CHANGE THE RIPARIAN EDGES OF STREAMS
AND RIVERS INTO WETLANDS, MEADOWS, OR RIVERINE
FORESTS. THESE DAMS HAVE SHOWN TO BE BENEFICIAL
TO MYRIAD OF SPECIES INCLUDING AMPHIBIANS,
SALMON, AND SONG BIRDS.
SUMMARY
• KEYSTONE SPECIES
• DOESN’T HAVE TO BE APEX PREDATOR BUT CAN BE.
• ITS ROLE MUST IRREPLACEABLE
• TENDS TO NOT HAVE ANY COMPETITION OR VERY LITTLE FOR ITS NICHE
• QUITE OFTEN IT IS NOT DISCOVERED TO BE THE KEYSTONE UNTIL IT IS TOO LATE, BUT THEN
OTHER ECOSYSTEMS CAN BE SAVED.
LINKS
• HTTP://WWW.YOUTUBE.COM/WATCH?V=KEH4R4IQIBU PRAIRIE DOGS
• HTTP://WWW.YOUTUBE.COM/WATCH?V=EUYXZAULKGK CASSOWARY
• HTTP://WWW.YOUTUBE.COM/WATCH?V=D3W4OCNHYCS SEA URCHINS
• HTTP://WWW.YOUTUBE.COM/WATCH?V=ARHWJTS2SG8 OTTERS VS CROCODILE
• HTTP://WWW.YOUTUBE.COM/WATCH?V=VUMRDZBRDXC BEAVERS BUILDING A LODGE
• HTTP://WWW.YOUTUBE.COM/WATCH?V=TJ800AOQPDQ ELEPHANT KNOCKING DOWN TREE
• HTTP://WWW.YOUTUBE.COM/WATCH?V=50TLF3KGBT4 MARULA FRUIT
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=ASJ82WYHISE SEA OTTERS VS URCHINS IN KELP FORESTS
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=UC7AHP5--EE SEA OTTER USING ROCKS TO OPEN CLAMS
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=DBNYWXDZ_PA JAGUAR HUNTING CAIMANS
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=ZUC4HJUETIM NEW HOLLAND HONEYEATER
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=CZUBGYT1YIU CASSOWARY DOCO
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=_M1LK_AMSZQ SWAMP LOGGERS VS BEAVER DAMS
• HTTPS://WWW.YOUTUBE.COM/WATCH?V=LU8DDYZ68KM BATTLE AT KRUGER