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ECO3A: Individs, Popns, Commun > Population Ecology (W7 L4) > Flashcards

Population Ecology (W7 L4) Flashcards

1
Q

Dispersal?

A

= movement of individual animals from place to birth to where it reproduces.

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2
Q

Dispersal attributes? (2)

A

• Based on an individual’s decision about where to occur on the landscape.
• Can also apply to seeds from plants & spores from fungi.

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3
Q

Dispersion & Distribution is based on?

A

Based on several individuals in a population.

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4
Q

Dispersal is based on?

A

Based on an individual’s decision about where to occur on the landscape.

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5
Q

Migration?

A

= movement back & forth between seasonal home ranges.

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6
Q

Local movement?

A

= fine-scale movement within home ranges.

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7
Q

Immigration/Emigration?

A

= movement into or out of a study area of arbitrary size or delineation (movement into or out of a population).

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8
Q

Dispersion?

A

= the spatial pattern of locations demonstrated by individuals (eg, animals, plants, fungi, bacteria) in an area.

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9
Q

Dispersion attributes? (2)

A

• Based on several individuals in a populations.
• Population level outcome of dispersal.

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10
Q

Distribution?

A

= the area occupied by a population or species depicted as a line drawn around a dispersion.

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11
Q

Forms of movement? (2)

A

● The minimum distance needed to reach the nearest unoccupied habitat.

● The longer distances, crossing suitable areas before settling in an ideal/optimal habitat.

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12
Q

Minimum distance needed to reach the nearest unoccupied habitat?

A

= animals wander around until they find places that are good enough.

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13
Q

Suitable areas in longer distances…?

A

= good enough areas.

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14
Q

Why is the 2nd form of movement a risky strategy?

A
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15
Q

Forms of mechanisms? (2)

A

● Young are pushed by parents out of the natural home range.

● There is a genetic or physiological prompt to move away from natal areas.

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16
Q

Explain 1st form of mechanism?

A

When mothers are planning to have more children & need space to keep those future young.

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17
Q

Egs of 1st form of mechanism? (2)

A

• Birds.
• Mammals (Rhino).

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18
Q

Eg of 2nd form of mechanism?

A

Salmon.

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19
Q

Forms of dispersal? (2)

A

• Pre-saturation.
• Saturation.

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20
Q

Pre-saturation dispersal?

A

= young leave the natal home range even if the population is in low abundance.

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21
Q

Saturation dispersal?

A

= young animals leave when the population reaches the threshold density determined by food availability/food limitation.

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22
Q

Pre-saturation dispersal attributes? (2)

A

• Common in small mammals.
• Happens before the population is saturated & full of competition.

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23
Q

When does Pre-saturation dispersal happen? (2)

A

Before population is saturated & full of competition.

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24
Q

Benefits of Pre-saturation dispersal? (2)

A

• Avoids inbreeding.
• Avoids competition for mates.

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25
Q

Saturation dispersal attributes? (2)

A

• Common in large mammals.
• Leave only when they suffer the effects of high competition (less resources).

26
Q

When does Saturation dispersal happen?

A

When competition is high (less resources).

27
Q

Eg of Pre-saturation dispersal?

A

Lemmings.

28
Q

Egs of Saturation dispersal? (2)

A

• Carnivores.
• Herbivores.

29
Q

Role of mating systems?

A

= play a role in how animals disperse from the natal home range.

30
Q

Role of mating systems involves…?

A

The General rule.

31
Q

The General Rule?

A

= males compete for reproductive opportunities, females are concerned with getting enough resources to support their reproductive efforts.

32
Q

Importance of the General rule?

A

Determines whether males tend to disperse or whether females tend to disperse.

33
Q

In promiscuous/polygynous species attributes? (2)

A

• Males tend to disperse more & more away from the natal home range as a strategy to find mates.

• Females remain in the natal home range (philopatric).

34
Q

Egs of promiscuous/polygynous species? (2)

A

• Kudu.
• Nyala.

35
Q

In monogamous species attribute?

A

Both males & females tend to disperse from natal home range (as they leave as a pair).

36
Q

Egs of monogamous species? (2)

A

• Hadeda ibis.
• Wolves.

37
Q

In higher vertebrates attributes? (4)

A

• Refers to birds & mammals.
• One sex tends to disperse more than the other.
• In mammals, it’s males.
• In birds, it’s females.

38
Q

Why is it that in mammals, under higher vertebrates, males are the ones to disperse?

A

It’s because females commit to offspring growth.

39
Q

Why is it that in birds, under higher vertebrates, females are the ones to disperse?

A

It’s because males defend nesting sites.

40
Q

Categories under the General rule? (3)

A

• In promiscuous/polygynous species.
• In monogamous species.
• In higher vertebrates.

41
Q

Factors driving dispersal? (3)

A

• Effort to reduce competition for mates.
• Effort to avoid inbreeding.
• Way to reduce competition for food/habitat resources.

42
Q

Explain eg of polygynous species? (2)

A

● Females tend to invest more in offspring than males therefore, whether they disperse or not depends on their ability to find adequate resources.

● Males are focused on finding mates therefore, whether they disperse or not depends on their ability to find mates.

43
Q

Inbreeding avoidance attributes? (3)

A

• Commonly cited idea.
• Isn’t clearly demonstrated.
• Depends on the species.

44
Q

Dispersers attribute/con/disadvantage of being a disperser?

A

Have lower survival.

45
Q

Why do dispersers have lower survival? (2)

A

Young animals with little experience moving through unfamiliar areas ¹don’t know where good food resources are & ²don’t know where protection from predators is.

46
Q

Egs of Dispersers? (2)

A

• Egyptian geese.
• Costs vs benefits of young oribi that would rather stay with their father to help defend his territory.

47
Q

Types of dispersion patterns? (3)

A

• Random.
• Clumped.
• Regularly spaced.

48
Q

Random pattern of Dispersion attribute?

A

No order to distribution/dispersion whatsoever.

49
Q

Eg of Random dispersion pattern?

A

Morula trees.

50
Q

Clumped dispersion pattern attributes? (2)

A

• Most common.
• Is the outcome of selection of ¹patchy resources, ²habitat, social groupings or ³anti-predator strategies.

51
Q

Clumped dispersion pattern is an outcome of the selection of what? (3)

A

• Patchy resources.
• Habitat, social groupings.
• Anti-predator strategies.

52
Q

Egs of Clumped dispersion pattern? (2)

A

• Elephants.
• Wildebeest.

  • Herding animals.
53
Q

Eg of Regularly spaced dispersion pattern?

A

Leopards.

  • Individuals.
54
Q

Ways to assess dispersion? (2)

A

• Grid cells.
• Nearest Neighbour Distance (NND).

55
Q

Grid cells attributes? (2)

A

• Put a grid over the study area.

• Within each cell, calculate ¹a mean number of points in each cell (x) & a ²standard deviation (sd).

56
Q

Problem with Grid cells method of assessing dispersion?

A

Conclusion depends on the size of the grid cell.

57
Q

Large grid cells attributes? (2)

A

• More cells with similar counts.
• More likely to conclude random dispersion but it might not be.

58
Q

Small grid cells attributes? (3)

A

• More cells with zero.
• Larger differences between cells.
• More likely to conclude Clumped dispersion even if it might not be.

59
Q

sd/x values for Grid cells? (3)

A

• sd/x ~ 1.
• sd/x > 1.
• sd/x < 1.

60
Q

sd ~ 1?

A

Dispersion is random.

61
Q

sd/x > 1?

A

Dispersion is clumped.

62
Q

sd/x < 1?

A

Dispersion is regular.

ECO3A: Individs, Popns, Commun (11 decks)

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