ECOL Community 1

Question 1

What is a community?

Answer 1

group of interacting individuals of different species

Question 2

What are food webs?

Answer 2

complex and realistic representations of predator/prey relationships

-organisms are grouped into trophic levels such as primary producers or primary consumers based on how they acquire energy

Question 3

What are food chains?

Answer 3

strictly linear representations of nutrient and energy flows through a community are often too simple to be used

Question 4

How can species affect each other on food webs?

Answer 4

through direct or indirect effects

Question 5

Example of direct and indirect effects:

Answer 5

-fish have DIRECT negative effects on larval dragonflies through predation
-fish have INDIRECT positive effects on pollinators and flowering plants (fish eat larval dragonflies which indirectly reduces # of adult dragonflies which are predators to pollinators, fewer dragonfly predators allows pollinator density to increase)

Question 6

What is community diversity?

Answer 6

takes into account both SPECIES RICHNESS and SPECIES EVENNESS

Question 7

Species richness

Answer 7

the # of species in a community

Question 8

Species evenness

Answer 8

the proportion of individuals in a community represented by each species

Question 9

What can be used to visualize both species richness and evenness within a community?

Answer 9

a rank-abundance curve

Question 10

On the rank abundance curve on the x axis what does 1 represent and what does 16 represent?

Answer 10

1 is the most abundant species
16 is the least abundant species

Question 11

Keystone species

Answer 11

-species diversity can be affected by the presence or absence of these
-could be a predator, parasite, herbivore, or competitor

Question 12

Grasses growing in the African savannas support large herds of grazing animals, such as wildebeests and zebras. In turn, the graders are food for lions and other large predators. Elephants eat the leaves of acacias and other savanna trees, sometimes pushing acacias over to reach the leaves. This browsing by elephants keeps acacia trees from covering the savanna. Grasses do not grow well in the shade of acacia trees.

Which species is a keystone species in this community?

Answer 12

elephants

Question 13

How can community diversity be affected?

Answer 13

by disturbance patterns

-when disturbance is rare, K-selected species can outcompete r-selected species
-when disturbance is frequent, r-selected species can outcompete K-selected species

Question 14

Where are more species present according to the intermediate disturbance hypothesis?