Lecture 11: Community ecology: trophic relationships and plant-animal interactions

Question 1

Tropic levels in order

Answer 1

Primary producers
Primary consumers
Secondary consumers
Tertiary consumers

Question 2

Primary producers

Answer 2

Plants

Question 3

Primary consumers

Answer 3

Herbivores

Question 4

Secondary consumers

Answer 4

Predators carnivores who eat herbivores

Question 5

Tertiary consumers

Answer 5

Carnivores eat secondary consumers

Question 6

Decomposers

Answer 6

Organism who eat deed organic matter

Question 7

Food chain vs food web

Answer 7

Food chains show linear path of energy flow

Food web more complex shows all different paths of energy flow

Question 8

Parasoids

Answer 8

Herbivores of plants

Question 9

Indirect effect

Answer 9

When affect of one species on another is mediated by third species

Question 10

Exploitative scramble competition

Answer 10

When organism compete for resources that are in short supply in an ecosystem

Question 11

Tropic cascades

Answer 11

Interactions between two tropic levels cascade to third tropic level

Question 12

Why is the world green according to Hairston?

Answer 12

Carnivores keep down herbivores so herbivores do not limit plant growth

Question 13

Effects of tropic cascades

Answer 13

Affects alternate across tropic levels

Can drastically affect communities

Question 14

Top down control

Answer 14

Abundances kept low because of predation

Question 15

Bottom up control

Answer 15

Abundances kept low because of resource limitations

Question 16

Solids lines on tropic cascade diagrams represent

Answer 16

Direct affects

Question 17

Dashed lines on tropic cascade diagrams represent

Answer 17

Indirect affects

Question 18

Take home message from tropic cascade and indirect affects(2)

Answer 18

Indirect affects can be as strong as direct affects

Outcomes not fundamentally predictable rely on strength of interactions

Long term experiment needed

Question 19

what are the most described species?

Answer 19

plants and animals

Question 20

why its is hard to be a herbivore

Answer 20

plants tissue is hard to convert to animal tissue

Question 21

why are plants tissue is hard to convert to animals tissue

Answer 21

Cellulose and lignin are tough, only be digested with help of microbial symbionts

Plant tissues heavily defended against
herbivores

Question 22

what is responsible for much of biodiversity in terms of plants and insects?

Answer 22

Coevolutionary race
between plants and insect
herbivores

Question 23

example of how plants defend themselves against herbivores

Answer 23

milkweed

Question 24

What are Milkweed-feeding specialist? What do they do? why do they do this?

Answer 24

monarch butterfly larva,
cutting leaf midrib to reducesap pressure before eating

Question 25

how do caterpillars get white sap from milkweed? benefit of this?

Answer 25

sequester it in their
cuticle, making themselves
poisonous and distasteful

Question 26

Describe Plant herbivore interactions as an arms race.

Answer 26

Plants evolve toxins to reduce herbivore predation

Insects evolve detoxification or other mechanisms to overcome plant defended

Question 27

Why do we think plants taste okay

Answer 27

Food crops have been artificially selected for low toxicity

Question 28

Are Secondary chemicals very potent or only a little bit potent?

Answer 28

Especially potent eg alkaloids

Question 29

What causes arms race

Answer 29

Escalation in defences

Question 30

What is the coevolutionary race between plants and animals responsible for?

Answer 30

Much of biodiversity

Question 31

What is the benefit of vertebrate herbivores having mixed diet?

Answer 31

Os they don’t have an over accumulation of one toxin from
the same plant