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BIOL 172 > Ch 53 Population Ecology > Flashcards

Ch 53 Population Ecology Flashcards

1
Q

Density

A

The number of individuals per unit area or volume

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2
Q

Dispersion

A

The pattern of spacing among individuals within the boundaries of the population

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3
Q

What two factors influence the spacing of individuals in a population?

A

1) Environmental factors

2) Social factors

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4
Q

In most cases, it is 1)___ and 2)___ to count all the 3)___ in a population

A

1) Impractical
2) Impossible
3) Individuals

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5
Q

Sampling

A

Techniques used to estimate densities and total population sizes

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6
Q

Mark-recapture method (definition)

A

A method for estimating population size by extrapolating from small samples

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7
Q

Mark-recapture method (steps)

A

1) Capture, tag, and release a random sample of individuals in a population
2) Marked individuals are given time to remix into the population
3) Scientists capture a second sample of individuals and note how many of them are marked
4) Population size (N) is estimated

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8
Q

Mark-recapture method (Equation)

A

N = (sn)/x

s = tagged individuals 
n = second captured sample 
x = tagged individuals in second sample
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9
Q

The actual density of a population is the result of what?

A

An interplay between processes that add individuals to a population and those that remove individuals

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10
Q

Process that add individuals to a population

A

1) Births

2) Immigration

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11
Q

Process that removes individuals from a population

A

1) Death

2) Emigration

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12
Q

Demography

A

The study of the vital statistics of a population and how they change over time

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13
Q

Life table

A

An age-specific summary of the survival pattern of a population

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14
Q

How is a life table best made?

A

By following the fate of a cohort

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15
Q

Cohort

A

A group of individuals of the same age

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16
Q

Survivorship curve

A

A graphic way of representing the data in a life table

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17
Q

Survivorship curve: Type I

A

Few deaths early on in life, most deaths within a small range of time later in life

18
Q

Survivorship curve: Type II

A

Relatively steady number of deaths throughout life

19
Q

Survivorship curve: Type III

A

Most deaths occur early on in life

20
Q

For species with sexual reproduction, demographers often concentrate only on ___ in a population

A

Females

21
Q

Fertility table (fertility schedule)

A

An age-specific summary of the reproductive rates in a population

22
Q

If immigration and emigration are ignored, a population’s growth rate equals 1)___ ___ minus 2)___ ___

A

1) Birth rate

2) Death rate

23
Q

A change in population size equals:

A

Birth + Immigrants - Deaths - Emigrants

24
Q

Mathematical expression for population growth

A

Births - Deaths

25
Q

Zero population growth (ZPG)

A

Occurs when the birth rate equals the death rate

26
Q

Exponential population growth

A

Population increase under idealized conditions

27
Q

Logistic population growth

A

A model where the per capita rate of increase declines as carrying capacity is reached

28
Q

Carrying capacity

A

The maximum population size

29
Q

Logistic population growth models are useful for:

A

Estimating possible growth

30
Q

Life history (definition)

A

Comprises the traits that affect its schedule of reproduction and survival

31
Q

Life history (traits)

A

1) The age at which reproduction begins
2) How often the organism reproduces
3) How many offspring are produced during each reproductive cycle

32
Q

Semelparity (Big-bang reproduction)

A

Reproduce once and die

33
Q

Iteroparity (Repeated production)

A

Produce offspring repeatedly

34
Q

What kind of environments favor semelparity?

A

High variable or unpredictable environments

35
Q

What kind of environments favor iteroparity?

A

Dependable environments

36
Q

R-selection

A

Selects for life history traits that maximize reproduction

Density-independent selection

37
Q

K-selection

A

Selects for life history traits that are sensitive to population density

Density-dependent selection

38
Q

Two general questions about regulation of population growth:

A

1) What environmental factors stop a population from growing indefinitely?
2) Why do some populations show radical fluctuations in size over time, while others remain stable?

39
Q

Density-dependent birth and death rates are an example of what?

A

Negative feedback that regulates population growth

40
Q

Factors that affect density-dependent birth and death rates:

A

1) Competition for resources
2) Territoriality
3) Disease
4) Predation
5) Predation
6) Toxic wastes
7) Intrinsic physiological factors

41
Q

Long-term population studies have challenged what?

A

The hypothesis that populations are relatively stable over time

BIOL 172 (29 decks)

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