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BSCI 1511 > Population Ecology > Flashcards

Population Ecology Flashcards

1
Q

When will an altruistic trait evolve? (Hamilton’s Rule)

A

An altruistic trait will evolve if the cost of the trait to the actor is lower than the benefit to the recipient times the relatedness between actor and recipient. (r x brecip - cactor > 0)

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2
Q

In Hamilton’s rule, what is r?

A

Relatedness: the probability that two individuals carry the same allele identical by descent (from previous generations) (ranges from 0 to 1)

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3
Q

What is a population?

A

A group of individuals of a single species living in the same general area.

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4
Q

How are populations described?

A

Populations are described by their boundaries, size, and changes in size

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5
Q

What is population ecology?

A

The study of populations in relation to the environment, including environmental influences on density and distribution, age structure, and population size.

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6
Q

What is density?

A

The number of individuals per unit area or volume.

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7
Q

What is dispersion?

A

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

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8
Q

List the steps of the mark-recapture method.

A
  1. Capture, tag, and release a random sample of individuals (s) in a population.
  2. Marked individuals are given time to mix back into the population
  3. Capture a second sample of individuals (n) and note how many of them are marked (x).
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9
Q

How is the data from the mark-recapture method used to estimate population size?

A

Formula: N = sn/x where N = population size, s = initial sample of individuals; n = second sample of individuals; and x = number of individuals from second sample that were marked.

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10
Q

What influences population size and density?

A

Births, deaths, immigration, and emigration.

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11
Q

Describe clumped dispersion.

A

Individuals aggregate in patterns (often according to high resource availability or favorable physical conditions).

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12
Q

Describe uniform dispersion.

A

Individuals are evenly spaced.

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13
Q

Describe random dispersion.

A

Individuals are unpredictably spaced. The position of one individual is independent of other individuals.

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14
Q

What is demography?

A

The study of the vital statistics of populations and how they change over time.

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15
Q

What are life tables?

A

Age-specific summaries of the survival patterns of populations, summarize some of the vital statistics. Life tables follow the fate of a cohort, a group of individuals from birth to death.

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16
Q

How are life tables built?

A

By determining the number of individuals that die in each age-group and by calculating the proportion of individuals surviving from one age class to the next.

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17
Q

What is survivorship?

A

The proportion of newborns (age = 0) surviving to age x.

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18
Q

What is the mortality (or death) rate?

A

The proportion of individuals of age x dying by age x + 1.

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19
Q

What is the survival rate?

A

Proportion of individuals alive at age x surviving to age x + 1.

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20
Q

What is age structure?

A

The relative number of individuals at each age in the population. Can be used to predict a population’s growth trends and can illuminate social conditions.

21
Q

In populations not experiencing immigration or emigration, what two key factors determine changes in population size?

A

Survivorship and reproductive rates.

22
Q

What is a survivorship curve?

A

A survivorship curve (age against log survivorship) is a graphic way of representing the data in a life table.

23
Q

Describe type I survivorship curves.

A

Type I curves have low death rates in early and middle of life (ex. humans).

24
Q

Describe type II survivorship curves.

A

Type II curves have a constant death rate over time.

25
Q

Describe type III survivorship curves.

A

Type III curves have high death rates for the young, but if those young survive to older age, they will live for a long time.

26
Q

Given these characteristics, decide which type of survivorship curve matches: Some parental care, more offspring, smaller body size.

A

Type II

27
Q

Given these characteristics, decide which type of survivorship curve matches: Parental care, few offspring, territoriality, large body size.

A

Type I

28
Q

Given these characteristics, decide which type of survivorship curve matches: No parental care, many offspring, very small body size .

A

Type III

29
Q

Why do demographers generally ignore males?

A

They focus only on females because they are the producers of offspring.

30
Q

What are the two key parameters of reproductive rates?

A
  1. Number of breeding females
  2. Age of reproductive females
31
Q

What is a reproductive table?

A

Aka a fertility schedule, it is an age-specific summary of the reproductive rates in a population.

32
Q

How is the change in population size (per capita rate of increase) calculated?

A

births + immigrants entering population - deaths - emigrants leaving population

33
Q

If immigration and emigration are ignored, how is a population’s growth rate calculated?

A

per capita increase = birth rate - death rate.

34
Q

How can births be expressed mathematically?

A

It can be expressed as the average number of births per individuals during the specified time. B = bN where B = births, b = annual per capita birth rate, and N = population size.

35
Q

How can deaths be expressed mathematically?

A

It can be expressed as the average number of deaths per individuals during the specified time. D = mN where D = deaths m = annual per capita death rate (mortality), and N = population size.

36
Q

How can the population growth equation be written mathematically?

A

∆N/∆t = (b - m)N

37
Q

How can the per capita rate of increase be calculated?

A

r = b - m

38
Q

For the per capita rate of increase equation, when r > 0, what happens?

A

When r > 0, populations grow.

39
Q

For the per capita rate of increase equation, when r < 0, what happens?

A

Populations shrink.

40
Q

For the per capita rate of increase equation, when r = 0, what happens?

A

This means the birth rate equals the death rate, so there is zero population growth.

41
Q

What is exponential population growth?

A

Population increase under idealized conditions. Under these conditions, the rate of increase is at its maximum, denoted as rmax (also known as the intrinsic rate of increase).

42
Q

What is the equation for the instantaneous growth rate?

A

dN/dt = rmax x N

43
Q

What are the assumptions of the exponential growth rate model?

A
  1. Birth and death rates are constant over time and resources are abundant.
  2. No age or size structure, and no difference in birth and death rates among individuals.
  3. Population is closed. No emigration or immigration.
  4. No time lags (for continuous model)
  5. No genetic structure.
44
Q

What is discrete growth?

A

Populations increasing or decreasing each year by a constant proportion do not have overlapping generations.

45
Q

What does lambda represent?

A

The finite rate of increase.

46
Q

How is the value of lambda interpreted?

A

When lambda = 1, zero population growth occurs. Populations grow when lamba > 1 and shrink when < 1

47
Q

How can lambda be mathematically expressed?

A

Lambda = Nsub(t+1) / Nsub(t)

48
Q

Generally, when does the exponential growth model apply?

A

It might apply in cases where limits to growth do not exist or have been removed.

49
Q

Give examples of where the exponential growth model might apply.

A
  1. In the lab
  2. In nature, but typically for relatively short time period.
  3. Newly established populations, especially with few predators.
  4. Invasive species, pest, or disease outbreaks.
  5. Populations recovering from catastrophic declines.
  6. Humans (ability to raise “carrying capacity” over time)

BSCI 1511 (32 decks)

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