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CHAPTER 4: SPECIES INTERACTIONS AND COMMUNITY ECOLOGY. COMPETITION PREDATION SYMBIOSIS TROPHIC LEVELS FOOD WEBS KEYSTONE SPECIES SUCCESSION INVASIVE SPECIES BIOMES. BIG PICTURE. Organisms interact within a community They exchange energy and materials
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CHAPTER 4: SPECIES INTERACTIONS AND COMMUNITY ECOLOGY • COMPETITION • PREDATION • SYMBIOSIS • TROPHIC LEVELS • FOOD WEBS • KEYSTONE SPECIES • SUCCESSION • INVASIVE SPECIES • BIOMES
BIG PICTURE • Organisms interact within a community • They exchange energy and materials • They are interdependent via feeding relationships • There are primary, secondary, tertiary...feeding relationships...or, trophic levels • There are producers and consumers • Communities that experience disturbance recover via various succession mechanisms • The Earth’s terrestrial ecosystems can be placed into a set of ten biomes
SPECIES INTERACTIONS: pp.78-83 • Given: some community • Species A • Species B • Interaction
SPECIES INTERACTIONS: pp.78-83 • Given: some community • Species A • Species B • Interaction • Table 4.1: Effects of Species Interactions on Their Participants!
SPECIES INTERACTIONS • COMPETITION • Individuals of different species compete for the same resources, within the same area, at the same time • Inter- v Intraspecific competition • Harmful to both individuals
COMPETITION EXAMPLES? • LEAPORD v LION • HYENA v LION
PREDATION • VERY GENERAL • ONE ANIMAL EATS ANOTHER • AN ANIMAL EATS A PLANT! • “Herbivory” • Predator v Prey • Beneficial v Harmful
PREDATION EXAMPLES? • LION --- GAZELLE • SNAKE --- MOUSE • FROG --- FLY
SYMBIOSIS • ONE ORGANISM LIVES ON OR IN ANOTHER ORGANISM (“Host”) • PARASITISM • MUTUALISM
SYMBIOSIS: PARASITISM • The parasite lives on or in the Host • It must have a stage where it can live independently... • Viruses are not “living”! • It benefits by robbing the Host of nutrition • It harms the Host via nutritional deficit, disease...but doesn’t “aim” to kill it.
PARASITE EXAMPLES • Tapeworm in human gut • Fleas/ticks on dogs
SYMBIOSIS: MUTUALISM • BOTH individuals benefit
MUTUALISM EXAMPLES • E coli bacteria in our gut • Cleaner fish/ Sharks • Pollinators....REMOTE!
OTHER RELATIONSHIPS • COMMENSALISM • NEUTRALISM • AMENALISM
OTHER RELATIONSHIPS • COMMENSALISM • One species benefits, the other is unaffected • Palo verde trees/ Sonoran Desert • Provide shade, keep soils moist • Benefits young plants
?? NEUTRALISM • Both organisms interact but no harm or benefit is apparent • ?? AMENALISM • One organism is harmed, the other “unaffected” • Rare and hard to differentiate from competition
MORE ON COMPETITION • Fundamental Niche • Realized Niche
RESOURCE PARTITIONING! • Species that would normally compete divide, or “partition”, the resources they use in common to minimize competition by becoming specialists