POPULATION ECOLOGY Flashcards

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1
Q

What is population ecology?

A

Population ecology analyzes the factors which affect population size and how any why it changes through time

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2
Q

What are the 2 important characteristics of any population?

A
  1. Density
  2. Dispersion of individuals
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3
Q

What is density?

A

Density is the number of individuals per unit area or volume

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4
Q

What types of sampling techniques can be used to estimate densities and total population sizes?

A
  1. Extrapolation from small samples
  2. An index of population size (e.g. bird nests, tracks, fecal droppings)
  3. Mark-recapture method
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5
Q

What is dispersion?

A

Dispersion is the pattern of spacing among individuals within the boundaries of a population

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6
Q

What is the formula for the mark-recapture method?

A
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7
Q

What are the 3 basic patterns of dispersion?

A
  1. Clumped - individuals aggregate in patches
  2. Uniform - individuals are evenly spaced due to direct social interactions
  3. Random - position of individuals is independent of others
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8
Q

Which is the most common pattern of dispersion?

A

Clumped

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9
Q

What is the most rare pattern of dispersion?

A

Random

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10
Q

What are demographics?

A

Demographics is the study of factors which affect the growth and decline of populations

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11
Q

What is a life-table?

A

A life-table is an age-specific summary of the survival patterns of a population

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12
Q

What is a survivorship curve?

A

A survivorship curve is a physical representation of a life-table, plotting individual numbers by their percent maximum lifespan

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13
Q

What is a type I survivorship curve?

A

Type I shows low death rates early in life; few offspring with a long parenting period; long life span; death rate increases with age (e.g. humans)

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14
Q

What is a type II survivorship curve?

A

Type II shows constant mortality, death rate constant with age (e.g. squirrels)

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15
Q

What is a type III survivorship curve?

A

Type III shows a high death rate early in life; many offspring with no parenting; short life span; death rate decreases with age (e.g. clams)

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16
Q

What is semelparity?

A

Semelparity are organisms which undergo a “one shot” pattern of ‘big bang’ reproduction, where a large number of offspring are produced and then die

17
Q

When is semelparity favored?

A

Where survival rate is low for offspring

18
Q

What is iteroparity?

A

Iteroparity are organisms which produce fewer offspring, but reproduce regularly

19
Q

When is iteroparity favored?

A

In more stable environments

20
Q

What kind of population growth does the exponential model of growth describe?

A

Idealized population in an unlimited environment

21
Q

What is the formula for change in population size?

A

r = B - D

When r < 0, population is shrinking

When r > 0, population is growing

22
Q

What is the formula for the exponential growth model?

A

dN/dt = B - D = rN

23
Q

What is the shape of the exponential growth model?

A

J-shaped curve

24
Q

What does the J-shaped curve for exponential growth characterize?

A

Recovering populations

25
Q

Wha kind of population growth does the logistical model describe?

A

Resources are typically limited, so population growth is therefore limited by carrying capacity (K)

26
Q

What is carrying capacity (K)?

A

Carrying capacity (K) is the maximum stable population size a particular environment can sustain without damage to the environment

27
Q

What is the formula for the logistical growth model?

A

dN/dt = rN[(K-N)/K]

28
Q

What is the shape of the logistical growth model?

A

S-shaped curve

29
Q

What does the logistic growth equation show?

A

That growth rate decreases as population size approaches carrying capacity because individuals are having to share resources

30
Q

What are density-dependent populations?

A

Density-dependent populations change population density with birth rates and death rates

Death rates increase with population density whereas birth rates decrease with population density

31
Q

What are density-independent populations?

A

Density-independent populations don’t experience a change in population density with birth and death rates

32
Q

What are density-dependent factors?

A

Density-dependent factors increase their effects on a population as population density increases

33
Q

What are density-independent factors?

A

Density-independent factors are unrelated to population density, and there is no feedback to slow population growth

34
Q

How do you estimate the time for doubling in population size?

A

Divide the number 70 by the percent for annual population growth

35
Q

The carrying capacity of Earth is hard to estimate, so what concept is used?

A

Ecological footprints (EFs) which summarize aggregate land and water area required by each person/city/nation to produce all the resources it consumes and to absorb all the waste it generates

36
Q

What are population pyramids useful for?

A

Population pyramids are useful indicators of the current state of a population structre and are a useful tool for planning, developing, or the delivery of goods and services