Lecture 31- Plant Animal Interactions

Question 1

What are the two types of plant-animal interactions?

Answer 1

1. Antagonistic = herbivory
2. Mutualistic = pollination

Question 2

What are some examples of co-evolution?

Answer 2

• Plant defenses
• Pollination
• Dispersal

Question 3

Existing relationships are _______

Answer 3

Sensitive

Question 4

Why are relationships sensitive?

Answer 4

• Short food webs
• Introduction of new species difficult
• Interact with few species
• Limited resources

Question 5

Describe the web from lichen and Arctic willow to Arctic wolf

Answer 5

Question 6

What does shrub encroachment onto tundra do?

Answer 6

• Outcompetes tundra plants
• Reduces biodiversity
• Removes species distribution eveness, get huge amount of one or two species

Question 7

Can berbivores reduce shrub density?

Answer 7

Yes (but browsing stress to reach a limit)

Question 8

How many caribou are required to reduce shrub density?

Answer 8

Requires 5 caribou per km^2

Question 9

What are some effects of microtines on shrubs?

Answer 9

• Exert grazing pressure on dwarf shrubs
• Reduce crowberry
• Less shrub cover allowing for more permafrost thaw and more carbon release
• Evergreen shrubs reduce warming and carbon release
• Declines in lemming population fluctuations

Question 10

Rare plants in the Arctic require ?

Answer 10

Specialized habitats

Question 11

Rare plants become ____ with climate change

Answer 11

More rare

Question 12

____ reduces common species

Answer 12

Grazing and trambling

Question 13

____ reduces rare species

Answer 13

Herbivore exclusion

Question 14

Describe how caribou increase permafrost

Answer 14

• Dig for lichens under the snow
• Reduce snow cover (insulating layer)
• Ground freezes more deeply
• Localized effect

Question 15

Describe how caribou can decrease permafrost

Answer 15

• At high densitites caribou can increase permafrost thaw
• Lower soil insualtion
• Pooling of water (decreased albedo)
• Accelerated permafrost thaw

Question 16

Describe the goose herbivory interaction

Answer 16

• Snow geese overgraze vegetation (also trample soil)
• Reduction in vegetation = loss of arthropod community
• Warmer soil temperatures
• Drier soils
• Shift of arthropod community to boreal species

Question 17

What pollinates white and yellow flowers?

Answer 17

Pollinated by flies

Question 18

What pollinates blue and purple flowers?

Answer 18

Pollinated by bumblebees

Question 19

____ pollinator diversity in the north

Answer 19

Low

Question 20

What predicts pollinators?

Answer 20

Flower colour

Question 21

What colour of flowers are in low and high abundance?

Answer 21

• Low = blue/purple
• High = white/yellow

Question 22

Why have yellow and white flowers?

Answer 22

• Flies attracted to yellow and white
• Lower energetic cost

Question 23

What colour of flowers would you find in glaciated and glacial refugia regions?

Answer 23

• Glaciated = yellow/white
• Glacial refugia = blue/purple

Question 24

Describe the relationship between carnivores and arctic plants

Answer 24

• Biopedturbation = animal caused soil disturbance
• Digging by grizzly bears = changes in soil moisture
• Burrowing by ground squirrels = patch of exposed soil that will be drier
• Maintains ecosystem heterogeneity or patchiness = increase plant species diversity

Question 25

How do Arctic foxes alter the vegetation?

Answer 25

• Arctic foxes use same den for many years
• Increased soil nutrients at den sites (fecal deposition, carcass remains)
• Allows for richer plant diversity
• Deeper snow on den sites