Lecture 14 Community Ecology Flashcards
Define Community
a group of different specie populations that live near one another and can interact
Define interspecific interactions
interactions between individuals of different species
What defines interspecific interactions?
the effects the interaction has on the organisms involved
What is intraspecific interactions?
Interactions between members of the same species
Define parasitism
+/- (Good for the parasite, bad for the host) relationship which the parasite derives nutrition from it’s harmed host
What is ectoparasite?
the parasite feeds externally on the host
What is an example of a ectoparasite?
Ticks feed on blood from host’s skin
What is an endoparasite?
The parasite feeds internally
What is an example of endoparasites?
Heart worms (live in dogs)
Tape worms (live in human GI system)
Define Commensalism:
+/0 (good for one organism, neutral for the other) relationship between two species where one benefits and the other is unaffected
Can you easily find a commensalism relationship?
No because species living closely together likely affect each other in some way
What is an example of commensalism?
African buffalo and egrets.
(Egrets eat insects stirred from grass by buffalo’s passing. Doesn’t affect buffalo BUT they eat parasites from buffalo skin. Therefore, it’s a blend of commensalism and mutualism)
Bird making a nest in a tree (they benefit with shelter, tree is unaffected)
Define mutualism
+/+ relationship where both species benefit
What is an example of mutualism in interspecific interactions?
Ants living in hollowed thorns of acacia wood. They get food, take care of acacia wood
What is a Savanna?
open grassy environment spread with MANY trees. Tey support large grazer populations and organisms rely on shelter
Why is a Savanna an unstable ecosystem?
If too many browsers eat too many trees, it becomes a grassland. If not managed well, it becomes a forest
How do you maintain savanna ecosystems?
Elephants are important browsers so they prevent the transition of scrub woods.
How are Elephants ecosystem enginners?
They have a massive, direct and physical alteration of the landscape. If they weren’t managing, it would be a forest
Define Ecosystem Engineer:
species that directly and dramatically affects physical environment (habitat is maintained or created)
How are ecosystem engineers determined?
They have a disproportionately large impact on ecosystem relative to number/biomass of individuals present
What prevents loss of savanna to elephant browsing?
On a tree with ants, if an elephant has rarely browed it -> mutualistic ants. If elephants maintain trees, no mutualistic ants found.
If an ant is found on a tree, elephant does not overbrowse.
What is a keystone species?
species with strong control over community structure as function of their niches (habitat is maintained or created).
Do keystone species physically affect the landscape like an ecosystem engineer?
No. They don’t physically affect the community
Define predation:
+/- interaction where one species eats another, killing the prey