Midterm #2

Question 1

Carrying Capacity

Answer 1

Total numbers of individuals of a species that can be sustained in a habitat in the long term.
Normally determined as the average population numbers of the species across multiple years

Question 2

Ideal Logistic

Answer 2

This is a smooth response
Rapid increase up to carrying capacity then it slowly planes off
Fast replicating species follow this

Question 3

Damped Oscillations

Answer 3

Rapid increase up to carrying capacity and past it.
Then falls below carrying capacity slight oscillation until it planes out at carrying capacity
More common than ideal logistic

Question 4

Stable Limit Cycle

Answer 4

Consistent rise and fall above and below carrying capacity
Sin wave
Common in insects

Question 5

Chaotic

Answer 5

Rapid increase past carrying capacity than a crash eventually rises again but in an unpredictable manner
Caribou of Pribilof Islands

Question 6

Density-dependant population regulation (limit population growth)

Answer 6

Due to intrinsic factors
Population numbers depend on the activity of individuals (birth rate, death rate, immigration, etc)
Regulation often occurs due to decreased births and increased mortality

Question 7

Mechanisms for density-dependant effects when populations exceed K (6)

Answer 7

Intraspecific competition: occurs when required resources are in limited supply
(Interference competition and differential ability to secure resources)

Delayed breeding or reduced offspring production: increase agonistic encounters increases the stress of sub-dominant individuals, reduces the birth rate

Larger territories when resources are limiting: Larger territories by dominant individuals leads to reduced access of sub-dominant males, leads to reduction of numbers of non-territorial members

Dispersal (migration): the leaving of individuals from a population as it reaches carrying capacity

Parasites/diseases: become more prevalent in denser populations, effectively culls population numbers

Predators: Predators are a major source of mortality in populations. Increased density of prey allows predators to expand in numbers and distribution

Question 8

Interference Competition

Answer 8

A form of intraspecific competition

Individuals directly interfere with others for limited resources

Question 9

Differential Resource Securement

Answer 9

A form of intraspecific competition

Some individuals will be better at getting access to necessary resources for survival

Question 10

Law of constant final yield

Answer 10

Regardless of the number of seeds planted you should end up with the same final yield under the same conditions
This is because the environment only supports so many individuals

Question 11

Factors limiting population growth (2)?

Answer 11

Density-dependent population factors and density-independent population regulation

Question 12

Crepuscular

Answer 12

An animal that is primarily active during twilight (during dusk and dawn)

Question 13

Cathemeral

Answer 13

Sporadic and random intervals of activity during any time of the day or night

Question 14

Niche

Answer 14

How an organism makes its living

Question 15

Resources

Answer 15

Contribute to population growth and whose availability can be reduced as a consequence of being consumed

Question 16

Substance

Answer 16

Too abundant to be altered by consumption are not included in those involved in competition

Question 17

Liebigs Law of the Minimum

Answer 17

Population numbers can be regulated by a single resource that has the greatest relative scarcity

Question 18

Interspecific Competition

Answer 18

This is competition between individuals of different species

Question 19

Gause’s Law of Competitive Exclusion

Answer 19

Two species with the same niche cannot coexist

Question 20

Evidence for interspecific competition in nature (4)

Answer 20

Habitat shifts in allopatry and sympatry

Character displacement: the tendency for 2 species to diverge in form when in sympathy

Habitat differences and resource partitioning: the ghost of competition past or competition in the present

Allelopathy: chemical competition in plants and animals (release of chemicals by one species to reduce the growth of others)

Question 21

Elton’s Niche

Answer 21

The role of a species in a community

Question 22

Hutchinson’s niche

Answer 22

all biophysical conditions that characterize the life of a species

Question 23

Fundamental niche

Answer 23

Is the entire multidimensional space that represents the total range of conditions within which an organism can function without limiting factors

Question 24

Realized niche

Answer 24

The actual multidimensional space that a species can occupy taking into account biotic factors such as predators, competitors and parasites

Question 25

Quantifying Niche Space

Answer 25

d = distance between two species in average resource use w = measure of resource spectrum breadth of a species d/w < 1 means no co-existence d/w > 1 means full co-existence

Question 26

Hutchinson's Concept of Niche Space

Answer 26

The multidimensional niche overlap of species Helps us understand how 2 species are really interacting Can be an nth hypervolume -- means there could be little overlap in hypervolume

Question 27

Lotka and Volterra Competition Model

Answer 27

dN/dt = rN [(K-N) - (αN2) / K] | The effect of species 2 on population growth of species 1

Question 28

Competition Coefficient (α)

Answer 28

This is the competitive overlap Measure of the inhibitory effect of species 2 on population growth of species 1 Amount of resource one individual of the population uses relative to the other

Question 29

Functional response curves (FRC)

Answer 29

Rate of food consumption and density of prey | Shows the rate at which food is consumed related to the density of the prey in the population

Question 30

FRC I

Answer 30

Linear model As prey density increases so do consumption linearly Single species Very rare Only when the predator has a high metabolism, and food is calorie poor Single prey species eaten

Question 31

FRC II

Answer 31

The exponential increase of prey consumption up to a level where it tapers off Because predator gets satiated or handling time poses a constraint Single prey species eaten

Question 32

FRC III

Answer 32

The quadratic increase followed by an inversion to exponential increases up to a flat line Slow initial increase do threshold of security Most common model Multiple prey species eaten

Question 33

Threshold of security

Answer 33

Minimum density under which no further predation occurs | Predicts that predators would rarely overexploit a prey species

Question 34

Compensatory predation (4)

Answer 34

``` At low prey densities: Reduced search efficiency Prey switching Search image Aggregated responses of predators ```

Question 35

Relative abundance of predator-prey (2)

Answer 35

Endothermic predators -- 1:300 | Ectothermic predators -- 60:300

Question 36

Prey defence (8)

Answer 36

``` Aposematic coloration Crypsis/camouflage Mullerian mimicry Batesian mimicry Protean behaviour Autotomy Structural defence Chemical defence ```

Question 37

Aposematic coloration

Answer 37

Brightly coloured individuals to alert predators that they are noxious or poisonous

Question 38

Mullerian mimicry

Answer 38

many poisonous species in similar areas develop a similar conspicuous colour pattern to mimic each other and reinforce predator avoidance

Question 39

Batesian mimics

Answer 39

These mimic noxious species in the habitat, but they themselves are not noxious

Question 40

Plant defence against herbivores

Answer 40

Plant structural defences | Plant chemical defences

Question 41

Antibrowsing compounds -- secondary metabolites (7)

Answer 41

``` Unpleasant odour Contact irritation Bitter taste Neurotoxins Proteinase inhibitors Growth hormone mimics Psychotropic effects ```

Question 42

Animal defence against plant chemical defence (3)

Answer 42

Mixed function oxidase -oxidation, reduction, hydrolysis Concentration of toxins Selective browsing

Question 43

Ecological Succession

Answer 43

The sequential change in species composition of the community over time

Question 44

Primary succession

Answer 44

the initial establishment of plant and animal communities on substrates lacking living organisms

Question 45

Secondary Succession

Answer 45

Change of an established community | Recolonziation of an already established habitat

Question 46

Allogenic succession

Answer 46

abiotic disturbance

Question 47

Autogenic succession

Answer 47

biotic disturbance

Question 48

Aggregation to the Transition state of biomass following clearcutting

Answer 48

The soil community dies following clear cut, so the detritus builds up. After soil community builds up the detritus begins to be broken down again, reducing the total biomass

Question 49

What factors are correlated to the rate of succession?

Answer 49

The temperature and rainfall. Faster succession under warmer and wetter conditions

Question 50

Ecological mechanisms for succession (4)

Answer 50

Stochastic events -- largely unpredictable, who gets there first and dictate early seral stages Facilitation -- a species creates conditions favourable for succeeding species but not itself Inhibition: a species inhibits the colonization of subsequent colonists (slows succession and prolongs a seral stage) Allelopathy or competitive exclusion Tolerance: members of the seral stage are those that co-exist due to the use of different resources Combines facilitation and inhibition into a co-evolutionary view of succession (the ghost of competition past)

Question 51

Some indices of the food web complexity (3)

Answer 51

Number of producers to top predator Total number of links (L) Connectance (C) - number of links in a food web divided by total number of possible links (N)

Question 52

How to calculate total number of possible links (N)

Answer 52

N = n(n-1) / 2

Question 53

Umbrella (indicator species)

Answer 53

Species used for conservation decisions

Question 54

Dominant species

Answer 54

a common species with an effect on the community proportional to its biomass

Question 55

Keystone species

Answer 55

a species with an effect on the community that is disproportional to its biomass

Question 56

Nutrient cycling downloading and uploading

Answer 56

Downloading: rivers discharge sediment, trace elements, dissolved organic matter, nitrogen phosphates Increased primary production in estuaries and adjacent marine waters Uploading: Movement of marine nutrients back into the terrestrial environment. Normally in the form of carcasses or guano Increase Nitrogen content of soils