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BIOL 213 > Chapter 53 - Population Ecology > Flashcards

Chapter 53 - Population Ecology Flashcards

1
Q

What is a population?

A

A group of the same species living in a defined area at a defined time.

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2
Q

What is population dynamics?

A

(Population ecology) the study of how a population changes over time

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3
Q

Population density

A

Number of individuals per unit area (terrestrial) or volume (aquatic)

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4
Q

Define immigration.

A

Individuals coming into a population (includes birth)

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5
Q

Define emigration.

A

Individuals moving away from a population (includes death)

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6
Q

How is population density measured?

A

Measure the number and density of individuals
Rates of demographic events (immigration/births, emigration/deaths)
Locations of individuals
Large populations vs small populations; mobile ones vs sedentary ones

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7
Q

Describe the Mark-recapture method.

A 
Scientists capture, tag, and release a random sample of individuals (s) in a population
Marked individuals are given time to mix back into the population
Scientists recapture a second sample of individuals (n) and note how many of them are marked (x)
Population size (N) = sn/x
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8
Q

Described clumped patterns of dispersion.

A

Most common in nature and often related to the environment

Can be a social thing (mating)

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9
Q

Describe uniform patterns of dispersion.

A

Species usually very territorial and in competition for resources.

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10
Q

Describe random patterns of dispersion.

A

Absence of any influences

Mostly wind pollinated plants

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11
Q

What is demography?

A

The study of population statistics/sizes and how they change over time

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12
Q

Describe the type I survivorship curve.

A

Starts off horizontal because of good parental care then drops off rapidly because of disease or lack of care; species usually have few offspring

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13
Q

Describe the type III survivorship curve.

A

Rapid drop off at the beginning because of no parental care with good survival after adulthood; common in species that produce tons of offspring

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14
Q

Describe type II survivorship curve.

A

Relatively constant/continuous death rate throughout; parental care depends on the species.

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15
Q

Define the per capital rate of increase.

A

Change in population size (per capita increase) = Births + immigrants entering population - Deaths - emigrants leaving population

Zero growth (ZPG): births = deaths or immigration = emigration

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16
Q

Describe exponential population growth.

A

Occurs when there is population increase under idealized conditions and results in a J-shaped curve.

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17
Q

When can natural populations grow exponentially?

A 
Release from predators
Increase in food availability 
Increase in shelter (which can increase release from predators)
Immunity to disease
Resistance to medicine
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18
Q

Why is the elephant population in Kruger National Park a J shaped curve? What are the axes to the graph?

A

It is a J-shaped curve because hunting was banned (release from predators)

Y-axis = elephant population 
X-axis = year
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19
Q

Why do the Northern elephant seals show a J-shaped curve? What are axes labeled as?

A

Banned hunting because they were endangered. Had increased food availability because squid isn’t overfished. Their predators (sharks) were hunted.

Y-axis = number of pups born
X-axis = year
20
Q

Describe carrying capacity (K).

A

Varies with the abundance of limiting resources (environment always changing)

21
Q

Describe logistic growth.

A

When some populations overshoot the carrying capacity before settling down to a relatively stable density resulting in an S shaped curve

22
Q

Define the Allen effect.

A

When individuals have a more difficult time surviving or reproducing because the population is too small. This is common for social species

23
Q

How do some species over come the Allee effect?

A

White rhinos: cooperative defense
Wind pollinated plants, corals: mate limitation
African wild dogs: group foraging
Pacific Salmon: habitat alteration

24
Q

Define life history.

A

The traits that affect its schedule of reproduction and survival. Can vary dramatically.

25
Q

What are the three main variables that a life history entails?

A
  1. Age which reproduction begins
  2. How often species reproduce
  3. How many are produced per reproductive episode
26
Q

Define semelparity.

A

(Big-bang reproduction): reproduce once then die; usually have a lot of offspring

27
Q

Define iteroparity.

A

Repeated reproduction. Occurs in most mammals

28
Q

Describe the “Trade-offs” and Life Histories - European Kestrels graph

A

Y-axis = parents surviving the following winter (%)
X-axis = reduced brood size (3-4 chicks), normal brood size (5-6 chicks), enlarged brood size (7-8 chicks)
Orange = male; Green = female
Showed that the best survivors had the fewest offspring because parents spent less energy caring for offspring

29
Q

What characteristics do species using r-selection (density-independent selection) have?

A 
Unstable, unpredictable environment
Reproduce rapidly
Little parental care
Small body size 
Early maturity
Short generation time
Ability to disperse quickly 
Examples: bacteria, plankton, mice, cats
30
Q

What characteristics do species with K-selection (density-dependent selection) have?

A 
Stable environment: don’t disperse
Compete successfully for limited resources
Late maturity
Few offspring and more parental care
Long-lived
Larger bodies
Examples: killer whale, elephants, lions
31
Q

What are the two general questions about regulation of population growth?

A

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

32
Q

What are the ways density-dependent populations decrease the population density?

A 
Resource limitation
Increase in predators
Increase in competition
Increase in territory
Increase spread of disease
33
Q

How do density-independent populations change density?

A

Typically abiotic (temperature, light, wind)

34
Q

Describe the Population Dynamics - Moose on Isle Royale, Michigan graph.

A 
Y-axis = number of wolves
X-axis = year 
Y-axis (right) = number of moose
Blue = wolves; red = moose
Wanted to see if the moose population is affected by abiotic or biotic factors. 
First decline = biotic because of wolves
2nd decline = abiotic (harsh winter)
35
Q

Describe the population cycles of the snowshoe hare and the lynx graph.

A

2 possible explanations: food limitation of the hare vs. predator-prey interactions

Y-axis (left) = # of hares (thousands) blue
X-axis = year
Y-axis (right) = # of lynx (thousands) red

First gave hares more food but didn’t work. Then protected hares with fence from lynx showing hypothesis 2 is correct for explaining boom-and-bust cycle

36
Q

What are the factors that help explain why population densities vary among species?

A 
Resource abundance
Size of individuals
Social organization
Introduced species
Evolutionary history
Polyploidy & Founder effects
Threatened species
Vicariance
37
Q

When a population becomes crowded and resource competition increases, what also increases?

A

Emigration

38
Q

What are metapopulations?

A

The overall population from linked smaller populations through immigration or emigration.

39
Q

Why are metapopulations patchy?

A

Organisms want to live in more populated areas

40
Q

What happens to that habitat if a local population goes extinct?

A

It might be colonized by immigrants depending on how suitable the habitat is.

41
Q

Why can the human population grow exponentially?

A

Unlimited resources
No natural predators
Have technology to create medicine to overcome disease

42
Q

Why is the human population rate of increase declining?

A

The rate of increase is slowing down because people are having babies later, there are more diseases and deaths, birth control slows population growth

43
Q

What are the two main ways to maintain zero population growth?

A

High birth rate with high death rate

Low birth rate with low death rate

44
Q

What is the demographic transition?

A

The move from high birth rate and high death rate to low birth rate and low death rate

45
Q

How do we measure if we have reached K?

A

Ecological footprint estimate land and water per person in calories

Per energy capita

BIOL 213 (6 decks)

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