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
What interaction is predation? (one word)
fleeting
Define herbivory:
+/- interaction in which an animal eats a photosynthetic organism, may or may not kill prey
Define interspecific competition:
-/- interaction between different species over competition of shared resources
Why is interspecific competition a -/- interaction?
They limit the other species’ ability to obtain the shared resource
Define ecological niche:
the sum of a species’ use of it’s living and non-living environment
Why can’t two species share a niche together?
one will ALWAYS outcompete the other -> competitive exclusion
Define competitive exclusion
two species cannot share a niche because they’ll outcompete the other
How does an inferior competitor affect competitive exclusion?
They’re like a 3yr old. Since they’re so grabby, They’ll still get something
Define resource partitioning:
differentiation of niches in response to interspecific competition that results in limiting shared resources
What is an example of resource partitioning?
Warblers forage at different portions of a tree
Define fundamental niche:
the full suite of resources potentially used by a species in absence of a competition
Define realized niche:
the portion of a species’ fundamental niche actually used in presence of a competition
What is an example of resource partitioning and niches?
Barnacle niche experiment
Describe the Barnacle Niche experiment:
Two different species of barnacles grew on a rocky coast. They feed on similar resources (filter feeders). Their environment and food is exactly the same.
One species was removed from the niche to observe other species change.
When one species was taken away, the other species expanded over the whole area of the rocky coast.
What inferences can we make from the Barnacle Niche experiment?
2 species use similar resources co-existing = resource partioning
realized niche -> niche occupied by a species in the presence of competition
What is an example of Interspecific relationships using beneficial bacteria?
Gut flora allow for proper digestion of food and protect your bowels from pathogenic bacteria.
antibiotics kill pathogenic and beneficial bacteria. Yet that can result in IBS and secondary infections.
Beneficial bacteria no longer check for growth of Clostridium Diff infections (pathogen) -> severe diarrhea.
To replace gut flora loss: fecal transplant (transpoosions)
What interspecific relationship best describes humans and bacteria?
Mutualism.
Gut flora eat from the food/have shelter. You’re able to better digest the food because of flora.
+/+
What interspecific relationship best describes C.diff and gut flora?
Competition.
They’re both fighting for resources (nutrients and shelter).
-/-
Define symbiosis:
individuals of two species live in direct, intimate contact with each other for long periods of time (physically touching for significant duration)
Define non-symbiotic interspecific interactions:
Species do NOT live in prolonged intimate contact but periodically associate with each other
What symbiotic relationship best describes humans and gut flora?
Symbiosis
Define trophic structure:
feeding relationships between organisms based on transfer of food and energy from primary producers and herbivores to carnivores.
What is a primary producer? (in regards to trophic structure)
Plants
What is a herbivore? (in regards to trophic structure)
primary consumers
Species at higher trophic levels can _______ affect species at lower trophic levels:
indirectly
Define trophic cascade:
effects of higher trophic levels trickle down to lower levels
What is an example of a trophic cascade?
Predators limit the density/behavior of their prey FINISH CARD
Between an otter, urchin and kelp trophic cascade, what happens when otters are removed from the environment?
Urchins are released from predation pressure so they eat more kelp, destroying kelp forest habitats. The indirect contact of otters via urchins affects kelp population. Lost two populations.
Between an otter, urchin and kelp trophic cascade, what happens when otters are kept from the environment?
Urchin population is maintained at a lower level, keeping kelp population intact.
What is the trophic cascade interaction diagram look like?
primary producer -> consumed by herbivore -> consumed by predator (food eats food)
How do you construct a trophic cascade interaction diagram?
Start with the food chain and direct contact. Draw solid arrows when one species is consumed by the other (shows energy flow). Construct indirect relationship of primary producer to predator. Draw dashed arrow for indirect relationship, +/- symbol next to arrow to represent impact on species the arrow points to.
How do you depict mutualism on trophic cascade interaction diagram?
Solid line for direct interaction (consumption). It’s double side because they very directly interact. + sign for relationship
How do you depict competition on trophic cascade interaction diagram?
When one organism and another compete from same resource, you have a double sided bracket with a (-) sign to show negative benefit
The presence of wolves ____ affect beavers based on ____
indirectly negative ; elks
The presence of wolves ____ affect trees based on ____
indirectly positive ; elks
