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LEC 23 Flashcards

Population Dynamics

1
Q

Biosphere

A

All of the ecosystems on earth

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2
Q

Levels of organization in human biology (SMALLEST TO LARGEST )

A

Atom/Molecule
Cell
Tissue
Organ
Organ System
Organism
Population
Community
Ecosystem
Biosphere

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3
Q

Ecosystem

A

consists of a community of organisms and the physical environment in which they live (living and non-living components combined)

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4
Q

Community

A

groups (populations) of different species that occupy the same geographic area and interact

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5
Q

Population

A

Groups of individuals of the same species occupying the same geographic area who interact with each other

  • groups within a community
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6
Q

Characteristics of Populations - Distribution (3)

A

The area where we can find a particular population

Also known as its “range”

Found here because the area is suitable to growth & survival

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7
Q

Characteristics of Populations - Population Density (2)

A

The number of individuals per unit area or volume

Tends to be higher in areas with plentiful resources

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8
Q

Characteristics of Populations - Population Density Trends (2)

A
  1. Larger body size of the organism, population density declines
  2. Smaller body size of the organism, population density increases
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9
Q

Growth

A

a population will grow when the number of births exceeds the number of deaths

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10
Q

Growth rates

A

Growth rate = ((# births - # deaths) x 100)) / total population

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11
Q

Biotic Potential

A

The maximum rate of growth of any population, under ideal conditions

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12
Q

Biotic Potential influenced by:

A

abundance of resources
(Enough food, water, habitat etc.)

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13
Q

Biotic Potential related to characteristics of the species (4)

A
  1. Usual number of offspring per reproduction cycle
  2. How often each individual reproduces
  3. Age when reproduction begins
  4. Ratio of males to females
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14
Q

Doubling Time of a Population

A

If you know the percent of change (for a period of time) in a population, you can calculate the time for that population to double in size

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15
Q

Doubling Time of a Population equation

A

Doubling Time = 72 / rate of change

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16
Q

Exponential Growth Also known as

A

theoretical growth

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17
Q

Exponential Growth Characteristics (4)

A

Occurs in ideal conditions (no limiting factors)

Population will double in size over a given time

Will continue to grow “unchecked” as long a resources are available

As population grows, the competition increases, may slow down rate of growth

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18
Q

Exponential Growth Graph

A

“J” shaped

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19
Q

Exponential Growth 2 phases

A
  1. Lag phase (slower rate of growth because number of individuals is small)
  2. Exponential phase (growth is accelerating)
20
Q

population growth will slow as conditions in the area change

A

environmental resistance

21
Q

Environmental resistance

A
  1. Finite resources & competition exist
  2. Anything that limits a species ability to consistently realize biotic potential
    - Things that kill organisms
    - Prevents them from reproducing
22
Q

Realized Growth AKA

A

logistic growth

23
Q

Realized Growth graph

A

“S” shaped curve

24
Q

Realized Growth 4 phases

A
  1. Lag
  2. Exponential
  3. Deceleration – rate slows due to increased competition for resources
  4. Stable equilibrium – little if any growth occurs
25
Stable Equilibrium
population finds balance between its biotic potential and environmental resistance
26
Carrying Capacity
population size the ecosystem can support indefinitely
27
Population size is _______ constant but rather hovers around _______ _________ over time
1. not 2. carrying capacity
28
Density-Independent Factors (3)
1. Cause sudden & catastrophic reduction in population size 2. Examples include weather and natural disasters 3. Effect is not influenced by the number of individuals in the population
29
Density-Dependent Factors (2)
1. The percentage of the population affected increases as the density increases 2. Examples include competition and predation
30
Competition (2)
1. Members of same species try to use same resources, which are limited in supply 2. Not all members of the population will have access to the resources to ensure survival
31
Predation
1. One organism (predator) eats another organism (prey) 2. Effect of predation increases as prey population increases (easier to find as there are less hiding spots)
32
Factors Regulating Growth
1. Density-Independent Factors 2. Density-Dependent Factors 3. Competition 4. Predation
33
Patterns in Ecology
1.Opportunistic species 2.Equilibrium species 3. Extinction
34
Opportunistic species
1. Tend to exhibit exponential growth 2. Members are small in size, mature early, short life spans and provide limited parental care 3. Density-independent factors limit population size
35
Equilibrium species (3)
1. Exhibit logistic growth 2. Members are larger in size, are slow to mature, have longer lives and invest in raising young 3. Population size affected mostly by density-dependent factors
36
Extinction (2)
1. Total loss of a species 2. Equilibrium species are often at higher risk
37
Human Population Growth - 4,000 years ago
population began to rise due to agriculture & domestication of animals
38
Human Population Growth - 1700’s
rapid growth with Industrial Revolution
39
Human Population Growth - Now
explosive growth with little (if any) environmental resistance
40
Some believe that the concept of _______ _______ doesn’t apply to humans because we can ______ our environment to suit our needs
1. carrying capacity 2. alter
41
Zero population growth
When the number of births in a population EQUAL the number of deaths
42
To reach Zero population growth, we need to either: (2)
Decrease birth rate Increase death rate
43
Fertility Rates
of children born to each woman during her lifetime
44
To reach zero population growth, the average fertility rate required is a ________ ___________ _____ of 2.1 children per woman
replacement fertility rate
45
Growth in More Developed Countries (MDC’s)
North America and Europe included in this group Populations grew rapidly between 1850 - 1950 Improved sanitation, medicine and overall socioeconomic conditions led to lower death rates Birth rates also lowered resulting in modest growth since 1950’s
46
Growth in Less Developed Countries (LDC’s)
Latin America, Asia and Africa Dramatic population growth, however, many individuals living in poverty Death rates dropped significantly after WWII due to modern medicine Birth rates remained high Still represents the majority of global population growth

BIO 105 (18 decks)

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