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Bio 94: Exam 3 > Chapter 53: Population Ecology > Flashcards

Chapter 53: Population Ecology Flashcards

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Biology 101 flashcards
1
Q

What is a population?

A

A group of individuals of the same species that occupy the same general area

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2
Q

What 4 factors influence population?

A

Density
Dispersion
Structure
Growth Rate

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3
Q

What is density?

A

The number of individuals per unit area or volume

  • density is the result of an interplay between processes that add individuals to a population and those that remove individuals
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4
Q

What is dispersion?

A

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

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5
Q

______ and ______ affect population size.

A

Births; deaths

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6
Q

What are the 3 types of dispersion?

A
  1. Clumped dispersion
  2. Uniform dispersion
  3. Random dispersion
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7
Q

What is clumped dispersion?

A

When organisms aggregate (group) in patches

  • this is due to resource availability and behavior
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8
Q

What is uniform dispersion?

A

When organisms are evenly distributed

  • this is due to social interactions such as territoriality (claiming territory)
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9
Q

What is random dispersion?

A

When the position of each organism is independent of other organisms

  • this is due to the absence of strong attractions or repulsions
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10
Q

What is demography?

A

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

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11
Q

What factors affect demography?

A
  1. Population size
  2. Density and Distribution
  3. Age Structure, Sex Ratio
  4. Birth, Death, Immigration and Emigration
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12
Q

What is age structure?

A

The relative number of individuals at each age

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13
Q

What is immigration?

A

The influx of new individuals from other areas

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14
Q

What is emigration?

A

The movement of individuals out of a population

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15
Q

What is a life table?

A

An age specific summary of the survival pattern of a population

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16
Q

What is the best way to construct a life table?

A

Follow the fate of a cohort, a group of individuals of the same age.

17
Q

What is a Type I species?

A

Species that invest a lot of energy into caring for their young
- have low death rates early in life

E.g., humans and large vertebrates

18
Q

What is a Type II species?

A

Species that have an equal probability of dying at any age

E.g., mammals and birds

19
Q

What is a Type III species?

A

Species that invest little energy raising their young
- high death rages among offspring

E.g., fish, invertebrates, plants

20
Q

What are the 3 types of population growth models?

A
  1. Constant Growth
  2. Exponential Growth
  3. Logistic Growth
21
Q

What is constant growth?

A

When the population continues to grow constantly

22
Q

What is exponential growth?

A

The increase of a population in an ideal, unlimited environment.

Equation:

^N/^t = rN

^N = change in population size 
^t  = change in time 
If r>0 = increasing population
If r<0 = decreasing population 
N = current population size
23
Q

What is the intrinsic rate of increase (r)?

A

The rate at which the population increases

24
Q

What is per capita rate of increase?

A

A population’s growth rate, which equals the birth rate minus the death rate.

^N/^t = B - D

^N = change in population size 
^t  = change in time
25
Q

What is expected of exponential growth?

A

It cannot continue on forever.

It has a ‘Carrying Capacity’ (K) (limit).
Either:
- the population will crash
- slower population growth

26
Q

What is the J-shaped curve?

A

An exponentially growing population that is rebounding after being reduced.

27
Q

What is logistic growth?

A

A population’s change over time in response to feedback from the environment or its own population density. (S curve!)

Equation:

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

dN = rate of change in population size 
dt  = rate of change in time 
If r>0 = increasing population
If r<0 = decreasing population 
N = current population size 
K = carrying capacity
28
Q

What are density-dependent factors?

A

Factors that cause a change in the population size that are related to the population density.

E.g., if you have a small density of 20 birds in a large forest, their population will continue to increase because they have plenty of resources. However, if you have a large density of 6,000 birds in a smaller forest, the birds will compete for their resources and the population may start to decline.

29
Q

What are density-independent factors?

A

Factors that cause a change in the population size that are unrelated to the population density.

E.g., if you have a population of 20 deer, or 50 deer, or 100 deer, and there’s a fire, it doesn’t matter how many deer you started with, what matters is that the population got affected regardless of how many there were.

30
Q

The effects of density-dependent factors _________ as the population density ______.

A

Increases; rises

33
Q

What is life history?

A

The events of an organism from conception to death.

  • it’s main focus is the adaptations that influence reproductive success
34
Q

How many humans can the earth support?

What is the carrying capacity of humans?

A

Average estimate is 10-15 billion

35
Q

What is the ecological footprint?

A

The aggregate (total) land and water area needed to sustain the people of a nation

  • how to measure our carrying capacity
36
Q

Which growth model explains human population growth?

A

Exponential

- slowly increased in 1650
No longer growing exponentially, but still increasing

37
Q

Life histories fall into two patterns shaped by natural selection.

a) Opportunistic species (r-selected)
b) Equilibrium species (K-selected)

Explain the differences between these two.

A

a) These organisms are short-lived, reproduce at an early age and have many offspring and provide little care.
- e.g., insects

b) These organisms are long-lived, reproduce later in life and provide extensive parental care.
- e.g., birds, large mammals

Bio 94: Exam 3 (8 decks)

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