Species Interactions; Herbivory

Question 1

What is herbivory a form of?

Answer 1

predation

Question 2

Define herbivory

Answer 2

One animal species eats all or part of a plant species

Question 3

What can herbivory lead to in plants?

Answer 3

• adaptations on parts of plant and also mutualisms

Question 4

why is the world considered to be green?

Answer 4

• herbivore numbers controlled by true predators, releasing plants from herbivory
• some plants/parts are inedible, having evolved adaptations to restrict the effects of herbivores

Question 5

Name two ways in which plants may adapt defences against herbivores

Answer 5

1. structural

2. chemical

Question 6

Name some examples of structural defences

Answer 6

thorns, tough leaves

Question 7

Name some examples of chemical defences

Answer 7

secondary plant substances

Question 8

What are the 2 suggested ways in which chemical defences could be?

Answer 8

• by products of metabolism concentrated in plant tissues

- chemicals evolves specifically to repel herbivores

Question 9

Name 2 defences of pedunculate oak

Answer 9

• dominant tree in deciduous woodland

- leaves attacked by more herbivore species than any other tree

Question 10

What did the growth experiment on leaves show?

Answer 10

• larvae fed young leaves grow better than those fed old leaves
• no adults emerged from pupae of individuals fed old leaves

Question 11

why could temporal variation in feeding be due solely to physical structure of leaves?

Answer 11

• larvae feed equally well on old and young leaves that have been ground up

Question 12

Why are some old species leaves that feed in summer very slow growth?

Answer 12

• low nutritional quality

- chemical change sin leaf

Question 13

Define tannin

Answer 13

secondary plant substance

Question 14

when does tannin increase in oak leaves?

Answer 14

from spring to autumn

Question 15

What is the role of tannin in leaves?

Answer 15

they bind proteins in complexes, reducing the palatability of leaves for herbivores

Question 16

How does tannin affect other species (animals)?

Answer 16

• species are reduced by tannin (winter moths)

- tend to feed in areas with no tannin

Question 17

Name the 2 ways in which oak treed defend themselves from herbivorous insects?

Answer 17

1) chemical- tannins

2) structural - altered leaf texture

Question 18

How do acacias and ants in the neotropics have a mutualistic system/coevolution?

Answer 18

• acacia depends on ants for defence against herbivores

- ants depend on acacia for food

Question 19

what are the effects on herbivores on teh Serengeti plains?

Answer 19

• defences reduce edibility of terrestrial plants
• in grazing systems, large mammals interact over food supply
• different herbivore species select different parts of the plant; sheath, stem, leaf

Question 20

what are the effect of wildebeest on grass productivity?

Answer 20

• heavily grazing as they migrate across the plains

- reduce plant biomass by 85% and plant height by 56%

Question 21

Describe an example of grazing facilitation among herbivorous mammals

Answer 21

zebra feeding improves grass for wildebeest and they in turn ‘prepare’ grass for exploitation by thomsons gazelle

Question 22

examples of herbivory in freshwaters

Answer 22

• invertebrates feeding on plants such as algae and macrophytes

Question 23

how can invertebrate herbivores control plant populations in streams but not in many terrestrial environments

Answer 23

because algae are small relative to herbivores and therefore easy to consume compared with terrestrial plants

Question 24

Name 4 factors herbivorous invertebrates can affect

Answer 24

• biomass
• taxonomic composition
• physiognomy (form)
• species richness

Question 25

what does the effect of grazing depend on?

Answer 25

- herbivore density and consumption rate - match between grazer mouthparts and algal structure - productive capacity of the algae

Question 26

Why is organism attack on leaves concentrated in spring?

Answer 26

- this is when the larvae is hatched | - leaves become less palatable as the plant ages, the leaf tissues matures