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Ecology > Chapter 9: Population Distribution and Abundance > Flashcards

Chapter 9: Population Distribution and Abundance Flashcards

1
Q

Distribution

A

geographic area where individuals of a species occur

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2
Q

Abundance

A

number of individuals in a given area

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3
Q

Population

A

a group of individuals of the same species that live in a particular area and interact with each other

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4
Q

Population Size

A

number of individuals

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5
Q

Population Density

A

Number of individuals per unit area

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6
Q

What are some problems that are had in population density studies?

A

-The total area occupied may not be known
-It is often difficult to know how far organisms or their gametes travel

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7
Q

How do they determine an area for population density studies?

A

An area is delimited based on best available knowledge of the species

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8
Q

Why can it be hard to determine what an individual is?

A

-Aspen trees produce clones (genetically identical copies) when new plants grow from root buds. A grove of Aspens may all be from the same individual
-Other organisms can do this too

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9
Q

How is an individual defined?

A

-Product of a Single Fertilization

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10
Q

Name of single genetic individual

A

Genet

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11
Q

Members of a genet that are independent physiologically, each member is called a….

A

ramet

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12
Q

Absolute Population Size

A

actual population abundance

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13
Q

Relative Population Size

A

number of individuals in one time period or place relative to the number in another

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14
Q

What are relative population size estimates based on?

A

-estimates are based on data presumed to be correlated with absolute population size
-Ex: number of cougar tracks in an area or number of fish caught per unit of effort

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15
Q

Methods for estimating abundance

A
  1. Area-based counts
  2. Distance Methods
  3. Mark and Recapture Studies
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16
Q

Methods for estimating abundance: Area Based Counts

A

individuals in a given area or volume are counted
-used most often to estimate abundance of plants
-Quadrants: sampling areas of specific size; must be a good representation of the entire area and are chosen at random or placed on a grid
-Individuals are counted in several quadrants; counts are averaged to estimate population size

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17
Q

Methods for Estimating Abundance: distance methods

A

Distance of individuals from a line or point are converted into estimates of abundance
-Line Transects: observer travels along a randomly place line, counts individuals and determines distance from the line
-A detection function converts distance measurements into an estimate of the absolute population size

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18
Q

Methods for Estimating Abundance: Mark and Recapture Studies

A

are used for mobile organisms
-a subset of individuals are captured again and the ratio of marked to unmarked individuals is used to estimate population size

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19
Q

Example of Mark and Recapture Study

A

-23 butterflies are captured and marked
-Later, 15 butterflies are captured, 4 of them marked
-Population is estimated

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20
Q

Dispersal

A

movement of individuals into (immigration) or out of (emigration) an existing population

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21
Q

Metapopulation

A

group of geographically isolated populations linked by dispersal

22
Q

Geographic Range

A

species might consist of one or multiple metapopulations

23
Q

Dispersion

A

spatial arrangement of individuals in a population

24
Q

Regular Dispersion

A

individuals are evenly spaced throughout their habitat

25
Q

Random Dispersion

A

individuals are randomly spaced

26
Q

Clumped Dispersion

A

more common in natural populations

27
Q

How many locations do endemic species occur in?

A

one location only, no where else on earth

28
Q

What all does geographic range include?

A

all the areas a species occupies during all life stages

29
Q

What may be the cause of patchy distribution?

A

abiotic factors

30
Q

Species Distribution Models

A

useful if the geographic range of a species is unknown or to predict spread of a pest species, or shifts in ranges due to climate change

31
Q

Example of a species distribution model

A

distributions of chameleons in Madagascar. a model used mapped environmental data along with “habitat rules” for each species to accurately predict the distribution of 11 species

32
Q

What determines distribution and abundance?

A

habitat suitability

33
Q

Abiotic factors

A

moisture, temperature, pH, light, nutrients, etc.

34
Q

What influences habitat suitability?

A

food availability

35
Q

What organisms affect species distribution?

A

Herbivores, predators, competitors, parasites, and pathogens

36
Q

What can interact to determine species distribution and abundance?

A

Abiotic and biotic factors

37
Q

Disturbance

A

events that kill or damage some individuals, creating opportunities for other individuals to grow and respond

38
Q

Continental Drift

A

Wallace 1860 observed very different animal species on the Philippines and New Guinea , even though they are very close together

39
Q

What caused continental drift?

A

discovery that two islands were on different tectonic plates, and have been close together for a relatively short amount of time

40
Q

Migration

A

type of dispersal in response to seasonal variation in resources; involves round-trip movement of whole population

41
Q

Dispersal Limitation

A

a species’ limited capacity for dispersal can prevent it from reaching areas of suitable habitat

42
Q

Van der Veken et al. 2007

A

-27 populations of English Bluebells were established experimentally in suitable habitat in 1960
-After 45 years, 11 populations persisted, hundreds or thousands of individuals
-suggests that dispersal limitation prevented the bluebells from reaching habitats where they could thrive

43
Q

Metapopulation

A

a set of spatially isolated populations linked to one another by dispersal

44
Q

How are metapopulations formed?

A

-some populations are sources of individuals that disperse to other populations
-other populations are sinks that receive more immigrants than the number of emigrants they produce
-individual populations may be prone to extinction but the meta population persists

45
Q

Levins (1969,1970)

A

represented meta population dynamics in terms of extinction and colonization of patches

46
Q

Model Assumptions of Levins 1969-1970

A

-a very large (infinite) number of identical habitat patches
-all patches have an equal change of getting colonists (spatial arrangement of patches doesn’t matter)
-all patches have an equal chance of extinction

47
Q

Habitat Fragmentation…

A

can result in metapopulations
-patches become smaller and more isolated; colonization rate may decrease and extinction rates increase

48
Q

Isolation By Distance

A

patches located far from other patches were less likely to be colonized; few patches separated by more than 2 km from an occupied patch were colonized during that period

49
Q

Why is patch size important to metapopulations?

A

larger patches were more likely to be colonized; small patches had highest rate of extinction

50
Q

Rescue Effect

A

high rates of immigration from a nearby patch that protects a small population from extinction

Ecology (12 decks)

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