Biology > Chapter 14- Population Dynamics > Flashcards

Chapter 14- Population Dynamics Flashcards

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1
Q

What do we need to calculate to study various species living in their respective habitats?

A

We need to calculate population size and density

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2
Q

Population size

A

Estimated number of organisms

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3
Q

Population density

A

Dividing the total numbers counted (N) by the space (S) occupied by the population

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4
Q

Whats an example of measure of population density

A
  • jack pine (380/hectare)
  • moose (0.8/hectare)
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5
Q

Why is population density deceiving?

A

It’s deceiving because of unused or unusable space within a habitat.

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6
Q

What are the two things scientists should measure in order to understand population?

A
  • population size
  • population density
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7
Q

What are the two types of densities to be measured?

A
  • crude density
  • ecological density
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8
Q

Crude density or Density

A

the number of individuals of the same species per unit area or volume

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9
Q

Ecological density

A

the number of individuals of the same species per unit area or volume actually used by the individuals.

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10
Q

Abundance

A

total number of individuals in the population

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11
Q

What’s an example of ecological density

A

Open lake water within the habitat area not normally used by the animal. So ecological density wouldn’t include that in its area

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12
Q

Three types of dispersions

A
  • Clumped dispersions
  • Uniform dispersions
  • Random dispersions
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13
Q

Why do we study dispersions?

A

Even though individuals belong to the same species, they may experience different challenges, resources, and ecological roles depending on where they live.

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14
Q

Suitable Niches

A

the places and situations where the organism can actually live successfully.

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15
Q

Clumped Disperson

A

The pattern in which individuals in a population are more concentrated in certain parts of a habitat

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16
Q

Uniform Disperson

A

The pattern in which individuals are equally spaced throughout a habitat

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17
Q

Random Disperson

A

The pattern in which individuals are spread throughout a habitat in an unpredictable and patternless manner

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18
Q

What causes clumped dispersion?

A

Environment/feeding is ideal or social behaviour

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19
Q

How is uniform dispersion caused?

A

There is competition for breeding, feeding, nesting.

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20
Q

Why does random dispersion happen?

A

Random dispersion is minimally influenced by other individuals and resources (like food, water, shelter) are evenly available.`

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21
Q

What are two ways biologists can measure population other than counting

A

They count a sample of the population at a particular time, then estimate a total size.

In some cases, an estimate or index of population size can be made using indirect indicators, such as the number of fecal droppings, tracks, nests or burrows

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22
Q

What is the quadrat useful for?

A

A common sampling technique for stationary or small organisms (plants/insects)

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23
Q

How is the quadrat used for?

A

One or more plots (or squares) can be counted, then the population size and density for the entire area can then be extrapolated based on calculations.

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24
Q

mark-recapture method

A

A sample of animals is captured, marked in some way, then released. After a period of time that allows marked animals to mix randomly with unmarked animals in the population, researchers capture a second sample.

In this sample, the proportion of marked animals to unmarked animals provides a basis for estimating the size of the entire population

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25
When is the mark-recaptured method used?
It estimates the size and density of mobile wildlife populations
26
What are 2 examples of sampling techniques
- quadrat - mark-recapture method
27
What's the difference between quadrat and mark-recapture method
Quadrat is used for stationary and small organisms while mark-recapture method is mobile wildlife
28
What 2 assumptions does the mark-recpatured method make?
- assumes that every organism has an equal opportunity to be captured over the time period from initial marking. - The proportion for marked to unmarked animals needs to remain constant, and the population size doesn’t change during the study
29
How does technological tracking work?
It involves radio collars or satellite-linked devices attached to the animals so that scientists can track migration and/or behavioural patterns
30
What's the advantage to technological tracking
It provides information with great accuracy as they also records light levels and duration, temperature and pressure.
31
Carrying Capacity
The maximum number of organisms that can be sustained by available resources over a limited period of time
32
What two factors affect the carrying capacity
abiotic and biotic variations in the environment
33
What is an example of an abiotic variation?
space (non-living physical and chemical elements)
34
What is an example of biotic variation?
food (living components of ecosystem)
35
Population dynamics
Changes in population characteristics determined by natality, mortality, immigration and emigration
36
Fecundity
have a potential to produce very large numbers of offspring (ex. fish vs. elephant offspring numbers)
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Why does population dynamics vary between species
different species have different fecundity
38
How many types of patterns of survivorship
3 patterns of survivorship
39
What is the 1st type of survivorship?
long life expectancy, slow to reach sexual maturity and low numbers of offspring.
40
What is the 2nd type of survivorship?
intermediate between type 1 and 3
41
What is the 3rd type of survivorship?
high mortality rate when young. Those that survive have a low mortality rate, and high numbers of offspring.
42
Mortality Rate
the number of deaths in a population over a specific time
43
What is a challenge to fertility?
There are many reasons why organisms usually produce far fewer actual offspring (fertility) than the maximum number they are biologically capable of producing (fecundity).
44
How to calculate change in population size?
[(births + immigration)–(deaths +emigration) / initial population size (n)] x 100%initial
45
What are the three ways population size can be expressed as
positive %, negative %, or zero growth
46
What are the two types of population growth
- open population - closed population
47
Open population
A population where changes in number and density is determined by births, deaths, immigration and emigration.
48
Closed population
Change in number and density determined by natality (birth rate) and mortality (death raate) alone (ex. on an island).
49
Natality
birth
50
What is the difference between open and closed populations?
Closed populations care for size changes from births and deaths ONLY but open populations also care for movement of population (immigration and emigration)
51
Biotic potential
The maximum rate a population can increase under ideal conditions.
52
What is a simple model?
They show graph changes in population size over time.
53
Geometric growth
A pattern of population growth where organisms reproduce at fixed intervals at a constant rate.
54
When does geometric growth usually happen for species
Breeding season
55
At what rate does geometric growth happen?
It happens at a constant rate
56
How can a geometric growth graph be determined
It can be determined by comparing the population size in one year to the population size at the same time the previous year.
57
What Greek letter represents geometric growth ratio?
The ratio is the Greek letter lambda
58
Whats the difference between geometric growth and exponential growth
growth occurs constantly, not just during breeding season.
59
What do both geographic and exponential growth assume and what's the issue with this assumption?
Both models assume that a population will continue to grow forever, but in reality, resources run out.
60
Logistic growth model
A model of population growth describing growth that levels off as the size of the population approaches its carrying capacity
61
How does the graph look for the logistic growth model?
It resembles a letter "s"
62
How many phases are there in a logistic growth model
3 phases in this growth model: - lag phase - log phase - stationary phase
63
Why are logistic growth models realistic?
They model the fact that resources in a population do eventually run out --> reproduction slows down & the number of deaths closely resembles the number of births --> a stable equilibrium is achieved --> happens when carrying capacity is almost reached
64
Lag Phase
Population is small and grows slowly.
65
Log Phase
Rapid growth
66
Stationary Phase
Population is at dynamic equilibrium (births = deaths)
67
Why is stationary phase triggered?
Because of environmental resistance - low resources, space, predation, disease, etc
68
What are the three growth models
- geometric model - exponential model - logistic growth model
69
Why are growth models useful?
These models can help researchers to predict patterns in population change based on data collected in the field.
70
What are the 2 factors that affect population change?
1. Density Dependent factors 2. Density Independent factors
71
Density Dependent Factors
A factor that influences population regulation, having a greater impact as population density increases or decreases.
72
Examples of density dependent factors
competition, predation, disease, parasitism
73
What is the allee effect
population can’t survive or fails to reproduce enough to offset mortality (death rate) once the population density is too low
74
What is the minimum viable population size
the smallest number of individuals that ensures the population can persist for a given amount of time
75
Density Independent Factors
Changes in the population size not related to density
76
If population isn't dependent on density, what then would population rely on?
Population size limited by human intervention or weather and environmental conditions.
77
Examples of Density Independent Factors
- environmental conditions - insecticides - flood - fire - drought - destruction of habitat.
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What are Density Dependent Factors also classified as
biotic
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What are Density Independent Factors also classified as
abiotic
80
Ecological niche
an organism’s biological characteristics, and its use of and its interaction between the biotic and the abiotic resources in its environment.
81
What are three classifications of interactions between two species?
1. Symbiosis 2. Competition 3. Predation
82
Symbiosis
Various interactions in which two species maintain a close, usually physical, association.
83
What are the three types of symbiosis
- mutualism - commensalism - parasitism
84
Mutualism
both organisms benefit (ex. pollination, bacteria in guts of animals).
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Example of Mutualism
Sea anenome and clownfish. - Clownfish lures in food for the anenome, while getting protection
86
Commensalism
one benefits and one is unaffected (ex. tree frogs use plants for protection).
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Examples of Commensalism
Barnacles on whales get a “free ride” and better access to food, and the whale is unaffected.
88
Parasitism
one benefits, one is harmed (ex. tapeworms, fleas, lice, ticks)
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Examples of Paratism
Tick harms a dog to get blood
90
Interference Competition
Actual fighting over resources
91
Exploitative competition
Consumption or use of shared resources
92
Population cycle
populations rise and fall over a predictable period of time.
92
What pattern could a graph show when prey and predators properly coexist? Explain why the pattern is that way.
Displays a cyclical pattern. The graph first shows prey increasing, followed by an increase in predators because there is more food But as predators multiply, the prey population falls because of increases in consumption. Once the prey population falls, predators therefore start to die off.This will then allow prey populations to start increasing again, and the cycle continues
93
2 Types of Defence Mechanisms
- physical defence mechanism - chemical defence mechanism
94
How do plants display the 2 types of defence mechanisms
Physical Defence Mechanism: such as thorns, spines, needles Chemical Defence Mechanism: various toxins
95
What are examples of ways that animals act defensively?
hiding, camouflage, mimicry
96
What are examples of ways that animals act actively?
fighting, chemical defense
97
What could cause a disruption in the ecosystem
Introducing an “exotic”or non-indigenous species disrupts by threatening biodiversity
98
What threat do non-indigenous species bring to exosystems?
They have few competitors and predators so they eliminate indigenous species (native species) by out-competing them for food and habitat
99
What are 2 examples of disruptions caused by non-indigenous species
zebra mussels in Ontario’s lakes and rabbits in Australia
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