Community Ecology II: Food Webs & Diversity

Question 1

What controls primary production? (growth of plants/algae)

Answer 1

• nutrients (nitrogen and phosphorus)

- grazing by zooplankton

Question 2

Top down control

Answer 2

Zooplankon grazing on algae (zooplankton is above algae on the food chain)

Question 3

Bottom up control

Answer 3

Algae absorbing nutrients (the nutrients are below algae on the food chain)

Question 4

Trophic cascades

Answer 4

Indirect effect of top predators on lower trophic levels

Question 5

Dominant species

Answer 5

Species that are most abundant or have the highest biomass

Question 6

Keystone species

Answer 6

Species that exert strong control on a community by their ecological roles or niches (i.e. sea stars)

Question 7

Biomass

Answer 7

The total mass of all individuals in a population within a community/weight of living organisms

Question 8

Ecosystem engineers

Answer 8

Influence other species by physically altering the environment

Question 9

Biodiversity

Answer 9

The variety of all life forms

Question 10

Species diversity

Answer 10

• richness = total number of species in a given area

- evenness = distribution of individuals among different species in a given area

Question 11

Patterns of diversity: (2 patterns)

Answer 11

1. habitat size

2. poles -> tropics

Question 12

Habitat size

Answer 12

Species-area curves

Question 13

Poles -> tropics

Answer 13

Less diverse -> more diverse

Question 14

The biodiversity crisis

Answer 14

Current rates of extinction are unusually high

Question 15

Mutational meltdown and extinction vortex

Answer 15

Positive feedback system: small populations tend to get even smaller
-intervention: reintroducing species from other populations (new genetic variability)

Question 16

Causes for modern extinction: (3 causes)

Answer 16

1. habitat destruction
2. introduced (invasive, exotic) species
3. overexploitation

Question 17

Habitat destruction

Answer 17

• loss

- fragmentation

Question 18

Introduced/exotic species

Answer 18

Species introduced to an area outside of their native range

Question 19

Invaders (invasive species) can: (3 things)

Answer 19

• alter habitats
• reduce or displace native species
• alter ecosystem services
• i.e. kudzu (southeastern U.S.)

Question 20

Common features of invasive species: (4 features)

Answer 20

• wide environmental tolerances
• large native range
• high rate of population increase (r)
• predator resistance/abundance

Question 21

Biotic homogenization

Answer 21

Via trade or intentional transports is like to contribute to establishment of invasive species

Question 22

Overexploitation

Answer 22

Harvesting of plant, animal populations at higher rates than population growth rates

Question 23

Solutions to modern extinction: (4 solutions)

Answer 23

• education and awareness
• biodiversity reserves
• reduce overexploitation
• restoration and remediation

Question 24

Reserves (conservation of 5 things)

Answer 24

Goals = conservation of:

• large, intact, functioning ecosystems
• areas of high biodiversity
• species or groups of species of special interest
• significant and natural communities
• important ecosystem services