Population ecology

Question 1

Key aspects of population ecology

Answer 1

1. Population Size and Density
2. Population Growth
3. Carrying Capacity (K)
4. Survival and Mortality
5. Reproduction
6. Interactions Within Populations
7. Dispersal
8. Life History Strategies
9. Human Impact

Question 2

Key aspects of life tables:

Answer 2

1. Survival Rates
2. Reproductive Rates
3. Population Growth
4. Age Structure
5. Resource Management
6. Comparing Populations

Question 3

Assumptions of Static Life Tables

Answer 3

1. A Stationary Population (for Some Variants)
2. Constant Age-Specific Mortality Rates
3. No Significant Migration Effects
4. Mortality Rates Apply to a Hypothetical Cohort
5. Deaths Occur Uniformly Within Age Intervals
6. The Oldest Age Group Experiences Complete Mortality
7. Survivorship Follows a Continuous Decline

Question 4

The number and range of ages in a subgroup of the cohort

Answer 4

Age class

Question 5

Number of individuals left alive belonging to that age group

Answer 5

Number alive

Question 6

Number of individuals dying belonging to that age group

Answer 6

Number dying

Question 7

% of the cohort that survived in that age group

Answer 7

Proportion surviving

Question 8

% of the cohort that died in that age group

Answer 8

Mortality rate

Question 9

It is an estimate of the total exposure of the cohort to mortality in that interval

Answer 9

Average number alive in age class

Question 10

It provides insight into the total number of years the cohort is expected to live from age x onward.

Answer 10

Total number of person-years lived beyond
age x

Question 11

Number of years an individual in that age group is expected to live

Answer 11

Life expectancy

Question 12

Feature

Basis of study: Follows a single cohort over time
Data Collection: Longitudinal (tracks individuals throughout their
lifespan)
Assumption: No migration; conditions remain stable across the cohort’s life
Best Use Case: Short-lived species, laboratory studies

Answer 12

Age-Specific Life Table
Cohort Life Table

Question 12

A measurement of observation time per person and is often used as the denominator in incidence rates when, for varying periods, individuals are at risk of developing a disease, using a health service, or dying.

Answer 12

Person years

Question 13

what does a 1.32 net reproductive rate mean?

Answer 13

What a female on average gives birth to
1.0 = stable population
Less than 1.0 = it decreases

Question 13

Feature

Basis of study: Observes all age groups at a single point in time
Data Collection: Cross-sectional (snapshot of the population)
Assumption: Stable age distribution and constant mortality rates
Best Use Case: Long-lived species, field studies

Answer 13

Time-Specific Life Table
Static Life Table

Question 13

Exponential growth is about

Answer 13

3.0

Question 14

why is fecundity schedule only computed for female?

Answer 14

In most species, females are the limiting factor
When asexual reproduction happens, reflect total offspring than females

Question 14

which age class should we most be conserved about for conservation

Answer 14

ages where the reproductive rate is the highest and the ages below it

Question 15

Survivorship curves

Convex, Adults mortality rate has more a late stage mortality rate, like hunting (K - selected), can survive the environment

Answer 15

Type 1

Question 16

Survivorship curves

Concave, high juvenile mortality but past that stage lives longer (R- selected)

Answer 16

Type 3

Question 16

Survivorship curves

Linear, mortality rate is constant at any age

Answer 16

Type 2

Question 17

Selection type
- high reproductive rate, high juvenile mortality, low parental investment

Answer 17

R- selected

Question 18

Selection type
- low reproductive rate, low juvenile mortality, high parental investment (carrying capacity), usually type 1, but can be type 2

Answer 18

K - selected

Question 19

At maturity, less than half survived (age class with most offspring)

Answer 19

Type III

Question 19

At maturity, .55 or .45 survivorship, (age class with most offspring)

Answer 19

type II

Question 20

At maturity, more than half survived (age class with most offspring)

Answer 20

Type I

Question 21

adaptive strategy Model small, short-lived; allocate more energy to reproduction, dispersal

Answer 21

Ruderal

Question 21

J curve is usually for what type of selected animals

Answer 21

R-selected

Question 22

population growth patterns Slows down at a maximum carrying site, plateaus at carrying capacity of the environment. Birth rate = death rate

Answer 22

logistic curve pattern

Question 22

population growth patterns Growth is slow at first Exponential growth after Leads to a crash and potential extinction

Answer 22

J curve

Question 23

logistic curve pattern is usually for what type of selected animals

Answer 23

K-selected

Question 24

adaptive strategy Model focuses on 3 factors

Answer 24

Stress - continuously present Disturbance - something happens Competition - fight between organisms

Question 25

adaptive strategy Model allocate more energy to maintenance

Answer 25

Stress-tolerant

Question 25

adaptive strategy Model allocate more energy to growth, resource acquisition and competition

Answer 25

Competitors

Question 26

low stress, low disturbance, high competition, stable habitats (oak and beech trees)

Answer 26

Competitors

Question 27

high stress, low disturbance, low competition, stable habitats (grow slowly, focuses on their own survival, lichens and cacti)

Answer 27

Stress tolerators

Question 28

low stress, high disturbance, low competition, (grow quickly, focuses on their own survival, lichens and cacti)

Answer 28

ruderals

Question 29

moderate competition, low stress (grow quickly, moderately disturbed ecosystems) (birch)

Answer 29

CR

Question 30

to which type of species are fluctuation more common?

Answer 30

R- selected have more fluctuations due to their nature of little parental care, survival is on the environmental factors and die very fast when one of the factors go wrong. Sensitive environment, tendency to overshoot.

Question 30

harsh or high stressed environment (small, short -lived, tolerates high stress)

Answer 30

SR

Question 31

only generalist, moderate all, (tolerates everything super moderately)

Answer 31

CSR

Question 31

to which type of species are cycles more common?

Answer 31

R-selected, has a boom and bust cycle.

Question 32

* spatial distribution of individuals (i.e., random, clumped/aggregated, hyperdispersed/uniform)

Answer 32

Dispersion

Question 32

In terms of logs and barnacles, are logs density dependent or density independent factors?

Answer 32

Density independent - the logs affect the population, the impact does not affect the density, it's only high or low. They occur randomly, and in the environment, such as storms. Density dependent - space on the rock, predation on barnacles

Question 33

2.5 represent number of offspring that become females (only in sexually reproducing population) What to exterminate ?

Answer 33

if the net reproductive rate is still more than 1, after extertminating the cohort with the most reproductive rates, add additional cohorts until it exceeds more than half.

Question 33

Main Regulation: Factor Competition, predation, disease Effect on Birth Rate: Declines as population grows Effect on Death Rate: Increases as population grows Growth Curve: Logistic (S-shaped) Population Stability: Stabilizes at carrying capacity

Answer 33

Density-Dependent Populations

Question 33

Is oxygen availability a density-dependent or density-independent factor for fish populations?

Answer 33

Yes, too much fish and limited oxygen kills fish. Ammonia spikes - density dependent, more fish can create more ammonia that can kill Temperature spikes - density independent, affects the population regardless of their density

Question 34

Main Regulation: Factor Climate, disasters, human impact Effect on Birth Rate: Remains constant Effect on Death Rate: Unrelated to population size Growth Curve: Exponential (J-shaped) Population Stability: Fluctuates unpredictably

Answer 34

Density-Independent Populations

Question 34

a demographic measure that indicates the average number of daughters a woman would have if she passed through her lifetime conforming to the age-specific fertility and mortality rates of a given period.

Answer 34

net reproductive rate

Question 35

* A group of conspecifics inhabiting a specific place in a specific time * A human construct

Answer 35

Population

Question 35

* may not be appropriate for clonal organisms, or those whose individuals or modules are difficult to distinguish

Answer 35

Population Density

Question 35

* Boundaries are defined by many means, mostly arbitrary: * relative to species ranges * relative to the life-span of individuals * to maximize important processes (e.g., reproduction, dispersal) within boundaries compared to those between the study area and other regions. * genetically; e.g., demes – locally defined population characterized by random mating within the group

Answer 35

Population

Question 36

* number of individuals per unit area or volume * can be expressed as crude density or as ecological density

Answer 36

Population Density

Question 37

the distribution of individuals in the various age classes

Answer 37

* Age Structure

Question 38

proportion or percentage of the population that is male or female

Answer 38

Sex ratio

Question 38

patterns of distribution *Commonest pattern that can observed in populations. *Individuals are bunched into groups within the population. *Mainly results from the response to the unevenly distributed resources in their environment

Answer 38

Clumped dispersion

Question 38

genetic individual arising from a zygote

Answer 38

genet

Question 39

Modules produced asexually by the genet are

Answer 39

ramets

Question 39

may be physically linked to the parent or separate are clones or exact copies of the parent genet

Answer 39

ramets

Question 40

patterns of distribution *Also happens if there are positive interactions between the individuals. *Advantages: * provides protection from predators, * Facilitates finding mates and reproduction *Decrease the energetic cost of food search

Answer 40

Clumped dispersion

Question 40

patterns of distribution

Answer 40

Clumped dispersion Uniform dispersion Random dispersion

Question 41

survivorship curves most individuals lost when older found in vertebrates especially those with parental care

Answer 41

Type I

Question 41

patterns of distribution * Individuals are randomly spaced within the community. * Not that much common in nature. * This occurs as there are no strong interactions between the individuals. * They show neutral interactions.

Answer 41

Random dispersion

Question 41

patterns of distribution * Individuals are uniformly spaced within the population. * Mainly results from the competition for resources. * Therefore there are aggressive interactions between the neighbours.

Answer 41

Uniform dispersion

Question 42

survivorship curves most individuals lost when young found in many invertebrates and plants

Answer 42

Type III

Question 42

sex ratios formula

Answer 42

* NE =(4NmNf)/(Nm+Nf)

Question 43

survivorship curves constant mortality rate in Hydra and many birds

Answer 43

Type II

Question 44

Any aspect of the developmental pattern and mode of reproduction of an organism that results from evolution (and not “conscious “decision”)

Answer 44

* Life History

Question 45

Opportunistic small organisms with good dispersal capabilities Short life spans, rapid development Early reproductive age Semelparous Fast population growth; variable population size below K

Answer 45

* R-selected

Question 46

reproducing or breeding only once in a lifetime

Answer 46

Semelparous

Question 46

Large organisms with poor dispersal capability but good competitive ability Long lived, slow development Late reproductive age Iteroparous Slow population growth; population size

Answer 46

* K-selected

Question 47

organisms that reproduce multiple times during their lifetime

Answer 47

Iteroparous

Question 48

Trade-offs in reproductive strategies

Answer 48

Number of offspring per reproductive event Present versus Future Reproduction Age at Sexual Maturity

Question 49

* _________ litters or clutches do not increase fitness since these are offset by higher mortality from predators, lower body weight of offspring, higher feeding costs, etc

Answer 49

larger

Question 50

selection favors age of _________ that occurs before survivorship declines markedly.

Answer 50

reproduction

Question 51

lower mortality rate at higher densities, destabilizing

Answer 51

inverse density dependence

Question 51

younger age of sexual maturity may be offset by ______ reproductive success

Answer 51

lower

Question 51

higher mortality rate at higher densities, stabilizing

Answer 51

density dependence

Question 52

no change in mortality with density

Answer 52

density independent

Question 53

the number of individuals or biomass per unit of available habitat space

Answer 53

ecological density

Question 53

density which considers the total area, focusing on the actual area colonized by a population

Answer 53

crude density