Lecture Six

Question 1

What are the three main types of species interactions?

Answer 1

Predation, competition, and symbiosis.

Question 2

What does predation result in?

Answer 2

A positive outcome for one individual and a negative outcome for another.

Question 3

What are three types of predation?

Answer 3

Carnivory, herbivory, and parasitism.

Question 4

What is carnivory?

Answer 4

An usually lethal form of predation.

Question 5

What is herbivory?

Answer 5

A typically non-lethal (but resulting in harm) form of predation.

Question 6

What is parasitism?

Answer 6

A typically non-lethal (but resulting in harm) form of predation.

Question 7

What is Coevolution?

Answer 7

When a one species acts as a selective force on another species, and the counter adaptation of the second species, in turn, affects the first species.

Question 8

How do predators and prey undergo coevolution?

Answer 8

Predators are strong selective forces on their prey. As predators adapt to prey, natural selection also shapes the prey’s defences.

Question 9

How have the Heliconius caterpillar and Passionflower plant coevolved?

Answer 9

Prey adaptations:

1) Toxic to most insects
2) Sugar deposits mimic eggs of Heliconius,
3) Scent of sugar attracts predators of Heliconius

Predator adaptations:
Plant is not toxic to Heliconius.

Question 10

What is Stalking Predation?

Answer 10

An adaptive predation strategy relating to speed; for example, a cheetah chasing a gazelle.

Question 11

What is Pursuit Predation?

Answer 11

An adaptive predation strategy relating to social coordination; for example, a pack of wolves chasing moose.

Question 12

What is Ambush Predation?

Answer 12

An adaptive predation strategy relating to morphology and camouflage; the yellow crab spider and the northern pike both exhibit this.

Question 13

How do plants combat predation?

Answer 13

Plants cannot run from herbivores, so they have adopted physical and chemical defences such as spines, thorns, leathery leaves, thick cuticles, poisons.

Question 14

How does the Acacia tree combat predation?

Answer 14

It sends chemical signals to other leaves when eaten, causing them to wilt and appear less appetizing.

Question 15

What are some poisons that plants may produce to defend against predation?

Answer 15

Strychnine, rotenone (used as organic pesticide), or unpalatable compounds like tannins. Milkweed causes a heart attack if eaten.

Question 16

What physical defences can animals have against predation?

Answer 16

Quills or spines, horns, pincers, stingers (bees), shells (turtle), tough hides, large size, odour repellents, various defensive behaviours, etc.

Question 17

What is Cryptic Coloration?

Answer 17

A defence against predation in animals, camouflage: colours or marking that help some organisms avoid detection from predators by blending into their surroundings.

Question 18

What is Aposematic Colouration?

Answer 18

A chemical defence against predation, animals may store toxins to deter predators. These animals are often brightly coloured, so that, predators may quickly identify them.

Question 19

What is Mimicry?

Answer 19

An attempt to mimic another, an effective defence mechanism.

Question 20

What are the two types of Mimicry?

Answer 20

Batesian mimicry and Müllerian mimicry.

Question 21

What is Batesian Mimicry?

Answer 21

The resemblance of a palatable or harmless species to an unpalatable or venomous species.

Question 22

What is an example of Batesian Mimicry?

Answer 22

Many predators learn to avoid the honey bee which is armed with a toxic stinger; because the flower fly resembles the honey bee, predators will also avoid it.

Question 23

What is Müllerian Mimicry?

Answer 23

When two unpalatable species that inhabit the same community mimic each other.

Question 24

What is an example of Müllerian Mimicry?

Answer 24

The cuckoo bee and yellow jacket have stingers and occupy the same communityand both are using similar coloring to signal their painful sting to predators.
This helps predators learn faster than if each had its own distinct coloration.

Question 25

What physical act can discourage predators?

Answer 25

Intimidation.

Question 26

What is Predator Satiation?

Answer 26

Synchronous production of progeny to overwhelms predators, resulting in some prey surviving.

Question 27

How does agility help prey?

Answer 27

Helps them out maneuver predators, such as the grasshopper’s ability to jump away.

Question 28

Why do predators rarely drive prey to extinction?

Answer 28

Natural communities are complex and contain many prey species, allowing predators to switch to other prey when an overexploited prey species becomes scarce. Predators themselves are often preyed upon, limiting their numbers and impact on prey. Prey have defensive mechanisms to prevent themselves from being overexploited.

Question 29

What is a Keystone Predator/Species?

Answer 29

A species with a dominant role in shaping the community structure. Their impact on the community far outweighs their numbers or biomass.

Question 30

What is an example of a Keystone Species involving starfish?

Answer 30

The Washington coast sea star consumes mussels from the intertidal region. When the sea star was removed from the community, the mussels grew to dominate. The number of species dropped from 15 to 8 when the sea star was removed and the mussel population exploded.

Question 31

Can predation increase or maintain diversity in a community?

Answer 31

Yes, by preying on species that would over dominate the community.

Question 32

What is an example of a Keystone Species involving otters?

Answer 32

The sea otter eats sea urchins, the sea urchins consume the kelp forests. When sea otters were annihilated for their furs, the sea urchin population exploded and the kelp forests were depleted - changing entire ecosystems.

Question 33

What is an example of a Keystone Species involving wolves?

Answer 33

Removing a species from a community can have unforeseen consequences. Wolves were exterminated from Yellowstone in the 20s, following which elk and moose populations increased - decreasing the deciduous vegetation and decreasing bird and small mammal populations due to habitat loss and decreased water quality due to increased erosion. The decreased berry producing plants decreased the grizzly bear population, and beaver populations decreased due to lack of trees.