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SLE103 Ecology And The Environment > Topic 10: Population Ecology > Flashcards

Topic 10: Population Ecology Flashcards

1
Q

What is the equation for population change?

A

Population change = (births + immigration) - (deaths + emigration)

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2
Q

What type of population has no immigration or emigration?

A

A closed population.
E.g. a population on a small island

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3
Q

What type of population has immigration and emigration?

A

An open population.
Most real populations are open populations

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4
Q

What is birth rate?

A

The number of young produced per female per unit time.

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5
Q

What greatly influences birth rate?

A

Parental care.
Birth rate is inversely related to the level of parental care.

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6
Q

What 6 factors influences death rate?

A
  • Longevity
  • Disease
  • Food availability
  • Predation
  • Parasitism
  • Random events
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7
Q

Why are immigration and emigration often assumed to be equal?

A

They are difficult to measure.
This is an important issue in patchy environments.

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8
Q

Population growth may be…?

A

Positive or negative.

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9
Q

What is the length of life of an individual called?

A

The longevity.

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10
Q

What is the mortality (death) rate?

A

The number of deaths per unit time.

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11
Q

What is exponential population growth?

A

Growth that occurs with a consistent multiplication over time.
Initial growth is small but over time, it increases more and more.
e.g. if 2 animals have 4 offspring, then both die, there is an increase of 2. So y = 2x -2, since the population is doubling.

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12
Q

What is a survivorship curve?

A

The mortality rate measured by marking individuals and plotting the survivors against time.

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13
Q

Why is exponentially growth not representative of real conditions?

A

It is based on ideal, unregulated conditions (unlimited food, no competition).
When a population is small, resources are unlimited, and there is explosive population growth, but as population increases, resources become limiting, and growth rates slow until an equilibrium is reached.

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14
Q

Which growth model incorporates the limiting factors that affect population growth?

A

A logistic population growth model, also known as a sigmoid model.

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15
Q

What is a population equilibrium?

A

Where the number of births is balanced with the number of births.
There is no net population growth - carrying capacity is reached.

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16
Q

What is population density?

A

The number of individuals per unit area.

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17
Q

What are the two types of population growth regulators?

A
  1. Density-dependent factors.
  2. Density-independent factors.
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18
Q

What are the 4 stages of population growth?

A
  1. Lag phase.
  2. Exponential growth stage. Also known as the log phase.
  3. The deceleration phase.
  4. The stable equilibrium phase.
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19
Q

What are the population limiting factors whose effects intensify as the population increases in density?

A

Density-dependent factors.
e.g. food supplies, space, breeding sites and poisonous waste products.
Increase of intraspecific competition

20
Q

What are population limiting factors that are not related to population density?

A

Density-independent factors.
e.g. weather conditions, including freezing or heatwaves. Occurs regardless of populatjon size.

21
Q

Is there a fixed carrying capacity?

A

No.
Seasonal and yearly differences in habitat cause fluctuations in carrying capacity.

22
Q

What are sessile organisms?

A

Not free-moving organisms.
e.g. mussels, barnacles or plants

23
Q

In the long term, what factors regulate most populations?

A

Both density-dependent and density-independent factors.

24
Q

Where do space-limited organisms live?

A

In habitats that experience disturbance.
These disturbances are necessary to create space to recruit new individuals.

25
Q

What characteristic of space-limited organisms allows them to colonise gaps that become available?

A

Widely dispersing propagates (seeds, spores, larvae).

26
Q

The rate of population growth can be reduced by…?

A
  1. Extending generation time.
  2. Reducing birth rate.
  3. Increasing death rate.
27
Q

What is the carrying capacity for the human population?

A

Undetermined.

28
Q

What do simple population models assume?

A

All individuals are the same age and size, with an equal probability of dying or giving birth.

29
Q

What is the age structure of a population?

A

The relative proportions of the population in different age classes.

30
Q

What is demography?

A

The statistical study of human population ecology.

31
Q

What are 3 population age structures?

A
  1. Expanding populations.
  2. Stable populations.
  3. Declining populations.
32
Q

What are expanding populations?

A

Populations with a large proportion of individuals in the juvenile age classes.

33
Q

What are stable populations?

A

Populations with an even distribution of age classes.

34
Q

What are declining populations?

A

Populations with a large proportion of individuals in older age classes.

35
Q

What is fecundity?

A

The ability to reproduce.
Fertility.

36
Q

Human population structure influences…?

A
  1. Economic well-being.
  2. Social aspects.
  3. Environmental impact.
37
Q

What are life tables?

A

Tables that show probability of death for different age groups.
Used to predict survivorship.

38
Q

What is life expectancy?

A

The average number of years of further life expected for a person of a particular age.

39
Q

What are the 3 types of survivorship curves?

A
  1. Type I. High survivorship throughout life, massive drop off at end of life. Includes humans.
  2. Type II. Constant loss independent of age. Includes birds and rodents.
  3. Type III. Early loss of life, less mortality after maturity. Includes oysters and trees.
40
Q

What are the 3 types of adaptions?

A
  1. Physiological.
  2. Anatomical.
  3. Behavioural.
41
Q

What does natural selection favour?

A

The combination of life-history traits that will maximum an individual’s reproductive success.

42
Q

What are 4 life-history traits?

A
  1. Frequency of reproduction.
  2. Number of offspring per breeding event.
  3. Amount of parental care.
  4. Longevity.
43
Q

What is fitness in an evolutionary sense?

A

The ability to pass on genes to the next generation.

44
Q

What are the 2 extreme life history strategies?

A
  1. Opportunistic life history: r-selected.
  2. Equilibrial life history: K-selected.
45
Q

What are 8 common characteristics of r-selected species?

A
  1. Live in unpredictable environment.
  2. Short maturation.
  3. Short lifespan.
  4. High death rate.
  5. Many offspring per event.
  6. One reproductive event early in life.
  7. Small offspring (or eggs).
  8. No parental care.

includes weeds, dandelions, locusts, mice and butterflies

46
Q

What are 9 common characteristics of K-selected species?

A
  1. Live in relatively predictable environment.
  2. Long maturation time.
  3. Long lifespan.
  4. Low death rate.
  5. Few offspring per event.
  6. Multiple reproductive events in lifetime.
  7. First reproduction occurs later in life.
  8. Large offspring.
  9. Extensive paternal care.

includes the Southern right whale and other large mammals

SLE103 Ecology And The Environment (11 decks)

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