Lecture: Chapters 15-16 Predation and Mutualism

Question 1

Importance of predation

Answer 1

• Defines food chains and food webs
• Determines behavior, population dynamics and spatial distributions of both prey and predator
• Driving force of adaptations; appears to be a stronger evolutionary force than other species interactions

Question 2

Predation

Answer 2

The consumption of one (live) organism by another, in whole or praty

Question 3

True predators

Answer 3

Organisms killing their prey and often consuming it in whole

Question 4

Grazers

Answer 4

Organisms consuming their prey (e.g. plants) in part, without killing them (e.g. some herbivores)

Question 5

Parasites

Answer 5

Organisms obtaining nutrients from (and usually attached or inside) a host, without necessarily killing it(one or few hosts per lifetime)

Question 6

Parasitoids

Answer 6

insects that lay an egg on or in another insect host. After hatching, larvae remain in the host, which they eat and usually kill

Question 7

Herbivores

Answer 7

Herbivores eat differnet parts of the plant. nitrogen content of plants is relatively low compared to animals

Question 8

Functional response

Answer 8

consumption rate of a single predator; number of prey consumed per predaotr per unit time

Question 9

Numerical response

Answer 9

predator reproduction rate

Question 10

Lotka-Volterra

Answer 10

Prey growth in the absence of predator : exponential - the functional response of the predator

Question 11

Type I functional response

Answer 11

The predator can increase its consumption indefinately as the prey population increases. Each predator consumes the same proportion of the prey population. This is unrealistic because of predator satiation (predator becomes full and stops feeding) and because of handling time

Question 12

Type II functional response

Answer 12

each predator consumes a smaller proportion of the prey population as the prey population size increases. If N is small, Type II model close to type I. This is due to handling time.

total feeding time = searching time + handling time

Question 13

Type III functional response

Answer 13

At high prey density, type III functional response is similar to type II for the same reasons. but at low prey densit, predator consumption increases at a slower rate and results in a n S shaped sigmoid curve

Question 14

Trade offs - optimal foraging theory

Answer 14

Foraging - survival, growth, reproduction; Defense ; Predator avoidance ; searching for mates ; carying for young

Question 15

Natural selection

Answer 15

may favor ‘efficient’ forages

• individuals maximize energy intake or intake of some nutrient per unit of effort
• maximize benefit (fitness) and minimize cost (time, energy spent on foraging)
• what toe at? maximize net energy gain
• many species may be required to satisfy nutrional requirements

Question 16

Physical defenses

Answer 16

• large size
• rapid movement
• body armor

Question 17

aposematic coloration

Answer 17

predators learn not to eat organisms that have toxins

Question 18

crypsis or cryptic coloration

Answer 18

the prey is camouflaged or resembles its background

Question 19

mimicry

Answer 19

the prey resembles another organism that is toxic or very fierce

Question 20

mullerian mimicry

Answer 20

co-mimicry among several species of noxious organisms

Question 21

batesian mimicry

Answer 21

harmless species mimic noxious species

Question 22

plants: predator satiation

Answer 22

some produce huge numbers of seeds in some years and hardly any in other years

the plants hide (in time) from seed-eating herbivores then overwhelm them by sheer numbers

Question 23

structural defenses

Answer 23

tough leaves, spines and thorns, saw-like edges, pernicious haris that can pierce the skin

Question 24

induced defenses

Answer 24

produced in response t herbivore attack. eg some catci increase spine production

Question 25

chemical defenses

Answer 25

secondary compounds: toxic chemicals to reduce herbivory

platn defneses can be overcome by herbivores

some herbivore have digestive enzymes that allow them to tolerate plant toxins

Question 26

symbionts

Answer 26

organisms that live in or on others organisms

Question 27

parasite

Answer 27

consumes the tissues or body fluids of the organisms on which it lives (the host)

Question 28

pathogens

Answer 28

parasites that cause diseases

Question 29

parasitoids

Answer 29

insects whose larvae feed on a single host and almost always kill it

Question 30

macroparasites

Answer 30

large
extracellular
grow but don’t reproduce inside host
arthopods and worms

Question 31

microparasites

Answer 31

microscopic, such as bacteria
often intracellular
usually reproduce within host
often very numerous

Question 32

ectoparasites

Answer 32

live on host
plant hosts
animal hosts

Question 33

endo parasites

Answer 33

live within host

tapeworms, bacteria

Question 34

hosts have adapatations for defending themselves against parasites, and parasites have adaptations for overcoming host defenses

Answer 34

parasites exert strong selection pressure on their host organisms and vice-versa

Question 35

Defenses and counterdefenses

Answer 35

Host organisms have many kinds of defense mechanisms

Protective outer coverings include skin and excoskeletons

many parasties that do gain entry are killed by the host’s immune system. Immune response has costs as energy is diverted from feeding, reproduction etc.

Question 36

vertebrate immune systems

Answer 36

have memory cells that can recognize microparasites from previous exposures

Question 37

using plants to fight parasites

Answer 37

some animals eat specific plants to treat or prevent parasite infections. Chimapnzees infected with nematodes seek out and eat a bitter plant that contains chemicals that kill or paralyze the nematodes

Question 38

parasites can reduce the sizes of host populations and alter the outcomes of species interactions thereby causing communities to change.

Answer 38

parasites can reduce survival or reproduction of their host

Question 39

mycorrhizae

Answer 39

symbiotic associations between roots and various fungi

Question 40

corals form mutalism with algae

Answer 40

they do. google it.

Question 41

obligation with species specific

Answer 41

tropical figs and fig wasps

Question 42

in mutualism

Answer 42

net benefits must exceed net costs for both partners