Community Ecology

Question 1

define Species interactions: consumptions

Answer 1

One organism eats or absorb nutrients from another (+/-)

Question 2

define Species interactions: Competition

Answer 2

Individuals use the same resources - resulting in lower fitness for both (-/-

Question 3

define Species interactions: commensalism

Answer 3

One species benefits but the other species in unaffected (+/0)
Example: orchid on a tree (host)

Question 4

define Species interactions: mutualisms

Answer 4

Two species interact in a way that confers fitness benefits to both (+/+)
Examples: flowers and pollinators, fish and cleaner shrimp

Question 5

whats a niche

Answer 5

range of resoucres that species utilizes and range of conditions it can tolerate

Question 6

difference between fundamental niche and realized niche

Answer 6

Fundamental niche: theoretical range of enviromental conditions that a species can tolerate
Realized niche: portion of fundamental niche that a species actually occupies, given limiting biotic interactions

Question 7

what is the Competitive exclusion principle

Answer 7

When two species compete for same limited resources and one is a better competitor than the other
Cannot coexist long-term

Question 8

key attributes of community structure

Answer 8

1.The total number of species
2.The relative abundance of those speices
3.The interactions amoung all soecies
4.The physical attributes of the community, including abiotic factors and biotic factors

Question 9

what are bottom up influences

Answer 9

Driven by abiotic condtions required by primary producers (eg: light availability, nutrients)
Susequent energy to transfer higher trophic levels (eg: kelp forests)

Question 10

what are top up influences

Answer 10

Consumers affect amount of species present in the community (eg: removing predatory sea stars results in dramatic decline in species richness)

Question 11

what is a trophic cascade

Answer 11

Strong indirect interactions that influence entire communities
Occurs when a trohpic level in a food web is surpressed by another
Example: top predator controls herbivore population; therefore, primary producers thrive

Question 12

what are keystone species

Answer 12

Have much greater impact of community structure than its abundance and total biomass would suggest (eg, beavers building dams)
Can have both top-down and bottom-down influences in a given community

Question 13

whats the Clements-Gleason Dichotomy

Answer 13

Henery gleason: communities are neither stable or predictable, largely a matter of chance whether a similar community develops in the same area after disturbance (ie: succession). He downplayed the role of biotic factors in structuring communities

Fredrik E Clements: communities are stable, orderly, highly predictable. Succession passes through predictable stages dictated by species interactions . Culminates in a stable final stage called climax community

Question 13

why do we know identical communities do not develop in identical habitats

Answer 13

In experiment 12 identical ponds were filled at same time with sterilized water. Found 61 species total, but each pond only has 31-39 species . Some species occurred in most or all ponds . Each pond had a unique species assemblage
Both hypothese supported
Although both biotic interactions and climate are important, chance plays large role