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ES 240 > Quiz 3 > Flashcards

Quiz 3 Flashcards

(70 cards)

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1
Q

Statistic

A

An estimate of a population parameter

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2
Q

Parameter

A

A measured value of a population

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3
Q

Statistical population

A

The total group of entities that are being studied

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4
Q

Sample

A

A subset of the population that is measured to produce the statistic

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5
Q

Ways to show uncertainty

A

Standard deviation, standard error, confidence intervals

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6
Q

What does a 95% confidence interval mean?

A

There is a 95% chance that the interval contains the parameter, or if the experiment was repeated 100 times, 95% of the intervals would contain the parameter

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7
Q

Overlapping confidence intervals

A

No significant difference. Do not reject the null hypothesis

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8
Q

Non-overlapping confidence intervals

A

Significant difference. Reject the null hypothesis

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9
Q

Which is larger a 99% confidence interval or a 95% confidence interval?

A

The 99% confidence interval

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10
Q

Does a confidence interval grow or shrink as confidence increases?

A

Shrinks

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11
Q

Range

A

The difference between the largest and smallest value in a sample

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12
Q

Normal distribution

A

A distribution where the spread of data about the mean is approximately symmetric. The mean, median, and mode are the same value

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13
Q

In a normal distribution how much data is within one standard deviation of the mean

A

68%

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14
Q

In a normal distribution how much data is within two standard deviation of the mean

A

95%

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15
Q

Equation for variance

A

The sum of the difference between each value and the mean of the sample squared. Then divide by the number of measurements in the sample

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16
Q

Standard deviation equation

A

Square root of variance

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17
Q

What does standard deviation tell you?

A

The variation within the sample. Does not apply to the wider population

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18
Q

What does a confidence interval tell you?

A

A range of values for the parameter in the wider population

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19
Q

Preston’s Veil line

A

Rare species that are assumed to be present, but cannot be adequately sampled due to low abundance

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20
Q

Statistical power

A

The probability that a test will correctly reject a false null hypothesis

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21
Q

Three ways to increase statistical power

A

Increase sample size, decrease natural or sample variation, increase effect size

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22
Q

Power curve

A

Relationship between sampling effort and sample power. Tells you how many samples to take for most efficient resource use

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23
Q

P value

A

The probability that a difference as large as the observed results would occur if the null hypothesis was true

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24
Q

When do we reject the null hypothesis

A

When the P value is less than 0.05

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25
Type one error
False positive - Concluding that there is a relationship when there isn’t
26
Type two error
False negative - Concluding that there isn’t a relationship when there is
27
Why are rockfish susceptible to overfishing?
They are slow-growing and take a long time to reach breeding age
28
What are the two methods of measuring rockfish abundance?
Scuba transects and baited underwater video
29
What were the areas of research in the rockfish study?
RCA efficiency, methods of measuring rockfish abundance, and effects of poaching
30
What was the conclusion about rockfish measurement methods?
Baited underwater video is better than scubA
31
What was the conclusion about effectiveness of RCAs?
Reference sites were better than RCAs
32
What was the conclusion about the effects of poaching on rockfish?
No significant difference
33
What is the most diverse kingdom?
Animals
34
What is the most diverse group of animals?
Insects
35
What is the most diverse group of vertebrates?
Fish
36
Diversity increases with...
``` Proximity to equator Decreasing altitude Increased precipitation Increased area Increased evapotranspiration ```
37
Why are there so few trees on the prairies?
High frequency of droughts, no wind cover, and high frequency of fire - high level of disturbance
38
What limits diversity in temperate forests?
Seasonal changes; species must either migrate or be generalists
39
Where is the most diversity and why?
Tropical rainforests, because there is lots of precipitation, high structural diversity, and a stable environment
40
Three levels of diversity
Genetic diversity Species diversity Ecosystem diversity
41
Alpha diversity
Number of species within a community
42
Beta diversity
Difference in species between two communities (number of unique species)
43
Gamma diversity
Regional diversity (sum of many communities)
44
Evapotranspiration
A measurement of the water produced by plant respiration
45
What can be measured as a proxy for primary productivity?
Evapotranspiration
46
How does evapotranspiration affect biodiversity?
Higher evapotranspiration implies higher primary productivity, and therefore causes high biodiversity
47
What determines species abundance?
Resource abundance and competition
48
Land requirements for herbivores vs carnivores
Herbivores and carnivores of the same weight require the same amount of land, even though meat is more energetically costly to produce. This is because more herbivores can share the same area than carnivores. Also, meat is more energy-dense than plants.
49
Minimum viable population size
The minimum number of individuals needed to maintain a population indefinitely
50
Disturbance is measured by:
Spatial extent, severity, frequency
51
Intermediate disturbance hypothesis
Species diversity is highest in areas of intermediate disturbance intensity
52
What drives diversity?
Competition and habitat gradients
53
Species range
An area with the right physical conditions for a species
54
Robert MacArthur
Created the theory that biodiversity increases stability
55
Robert May
Used computer models of communities with randomly assigned interactions. Found that increased diversity decreases stability
56
Peter Yodzis
Created computer models easing empirical data from real ecosystems. Found that it is not species diversity that causes stability, but instead diversity in interactions between species
57
Strong interactions
Interactions between species which are frequent or significant
58
Weak interactions
Interactions between species which are in frequent or less significant
59
Why does introduction of bluegills increase bullfrog populations?
Bluegills preferentially eat dragon fly larvae, which eat bullfrog tadpoles
60
Stanley Milgram
Performed an experiment to understand social networks in the US. Sent packages to random individuals and ask them to send the package to the person that they knew on a first name basis who would have the best chance of knowing a specific person in Boston. The average path length was found to be 5.5 links
61
Hub
A highly connected node within the network. Helps to reduce path length by connecting lots of individuals
62
Paul Erdos
Random network theory: as the number of individuals in the network increases, the proportional path length needed to cover the network decreases
63
What is the problem with random network theory?
It doesn’t take clustering into account
64
Small world networks
A network with the average path length is small compared to the number of notes. These networks are in between random networks and structured networks. Small world networks are the most efficient network structure for transferring materials through the network
65
Why do ecological systems have small world networks?
Small world networks are the most efficient networks, so they arise through evolution
66
Granovetter
Developed the idea of strong and weak links
67
Keystone species
Species which has a small biomass, but a large impact on the ecosystem
68
Why are starfish a keystone species?
Because they control the mussel population and prevent mussels from taking over the entire area. When starfish or removed, about 50% of species are lost
69
What is the role of keystone species?
They help to maintain weak links and relationship diversity within communities
70
Dominant species
A species that has a large biomass and a proportionally large impact

ES 240 (5 decks)

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