Population ecology Flashcards

1
Q

What is population size?

A

the number of individuals

larger populations = larger variety = more potential for adaptation

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2
Q

What is population density?

A

the number of individuals per unit geographic area

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3
Q

What are population density limiting factors?

A

limitations to population growth

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4
Q

What are the 2 types of population density limiting factors?

A

density-dependent

density-independent

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5
Q

What are density-dependent population density limiting factor?

A

disease OR Predators

competition Availability of resources

predation Nutrient supply

food Disease

nesting sites Accumulation of wastes

mates

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6
Q

What are density-independent population density limiting factors?

A

often abiotic OR Phenomena

sunlight Abiotic factors

temperature Weather conditions

reainfall

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7
Q

What are terms to describe population distribution?

A

Random

Clumped

Uniform

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8
Q

What is the difference btw natality and mortality?

A

natality -
increase population size as offspring are added to the population

mortality -
decreases the population size as some individuals get eaten, die of age, get sick

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9
Q

What is the difference btw immigration and emigration?

A

immigration -
increases population size as individuals have moved into the area from somewhere else

emigration -
decreases the population size as individuals have moved out of the area

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10
Q

What is the population size formula (general)?

A

Pop. size = (Immigration + Natality) - (Mortality + Emigration)

Mnemonic:
Pee IN ME

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11
Q

What are the phases of the sigmoid population growth curve?

A
  1. Exponential
  2. Traditional
  3. Plateau
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12
Q

What occurs during the exponential phase of the sigmoid curve?

A

rapid increase of population

natality > mortality

Resources = ABUNDANT

Diseases + predators = RARE

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13
Q

What occurs during the traditional phase of the sigmoid curve?

A
natality = DECREASE
mortality = INCREASE

Resources = DECREASE

Pop. = increase but at SLOWER RATE

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14
Q

What occurs at the plateau phase of the sigmoid curve?

A

No more population growth = constant population size

natality = mortality

pop. reached CARRYING CAPACITY of environment

resources = limited

Predators + disease = common

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15
Q

What is carrying capacity?

A

is the MAXIMUM a population size that can be supported by the environment

e.g. if pop. is limited by resource shortage = carrying capacity

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16
Q

What are r reproductive strategies?

A

small resource investment
= low effort babes

nop protection
= increase mortality %

egg fertilised THEN dispersed

More common for animals wt shorter lifespan

17
Q

What are k reproductive methods?

A

relates to carrying capacity (competitive world)

heavy investment (i.e protection + parenting)
   = increase survival %

common in larger animals + animals that are long lived wt longer period of maturation + adulthood

18
Q

How can you measure a population size?

A

Immigration + Natality + Emigration + Mortality + limiting factors
= IMPRACTICAL TO COUNT POP. OVER LARGER AREA

therefore: SAMPLING e.g.

sampling -
identifying individual #s in small areas (RANDOM + UNBIAS) then estimating totals

quadrats -
for non-mobile / sessile species

19
Q

How does the capture-mark-release-recapture sampling method used?

A

area defined & marked off

selection of individuals captured, counted, marked, released (n1)

after time (n1 reintegrated) second capture made (n2)
all animals (marked & not marked) counted (n3)

related to Lincoln Index

20
Q

What is the Lincoln Index?

A

pop. size = (n1 x n2) / n3

n1 = # in 1st capture
n2 = # collected in 2nd capture
n3 = # marked in 2nd capture
21
Q

What are the assumptions associated wt the Lincoln Index?

A
  1. ALL INDIVIDUALS EQUAL CAPTURE %
  2. MARKED individuals RANDOMLY DISTRIBUTED after release (n1 CANNOT AFFECT n3)
  3. MARKING will NOT AFFECT natality + mortality
22
Q

How can Lincoln Index accuracy be improved?

A

Increase capture sample size

take REPEATED samples

23
Q

What are quadrats?

A

a square wt a known frame

placed randomly then count # of species/ coverage %
REPEAT

observe presence / absence of species
therefore, # quadrats wt both species compared to total # quadrats

24
Q

What are the quadrat formulas?

A

pop. size = (mean # per quadrat x total area) / area of each quadrat

estimated average density = total # individuals counted / (# quadrats x area of quadrat)

25
What is the purpose of the chi square test?
tp determine if there is a statistically significant association btw distribution of 2 species applied to quadrat sampling CAN ONLY USE IF > (or equal to) 5 frequency & random sample
26
What are the steps to the chi square test?
1. hypothesis (null / alternative) 2. table of frequencies (observed & expected) 3. formula 4. degree of freedom (fd) 5. 'p' value
27
What does the hypothesis step of the chi square test consist of?
null (H0) 2 species INDEPENDENTLY distributed alternative (H1) 2 species associated POSITIVELY or NEGATIVELY
28
What does the table of frequencies step of the chi square test consist of?
make a table of observed frequencies make a table of expected frequencies using formula: (row total x column total) / grand total
29
What does the chi squared formula step of the chi square test consist of?
apply formula and insert calls into the TOTAL areas formula: x^2 = (sum of (O - E) ^2) / E ``` O = observed frequency E = expected frequency ```
30
What does the degree of freedom step of the chi square test consist of?
mathematical restriction the designates what range of values fall within each significant level df = (m - 1) (n - 1) ``` m = # rows n = # columns ``` when distribution patters for 2 species compared : D SHOULD ALWAYS = 1
31
What does the 'p' value step of the chi square test consist of?
determines if result is statistically significant (< 5% probability = p < 0.05)