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Population Ecology > Abundance > Flashcards

Abundance Flashcards

1
Q

Define abundance

A

The number of individuals in a sample

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2
Q

What is relative species abundance ?

A

How rare a species is in comp to other species in the community

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3
Q

Define Regulation.

A

The tendency for a population to decease in size if above a certain limit and to increase if below a certain level.

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4
Q

What is determining abundance ?

A

The combined effects of all processes that affect a population

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5
Q

How do we measure abundance ?

A

Rely on sampling

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6
Q

List the 4 main methods of sampling.

A 
Use of transects and quadrats 
Camera trapping 
Catch effort (remove organisms)
Indirect measures 
(prints, nests, burrows, faeces)
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7
Q

Outline the mark release recapture method

A

Portion of population is captured
These individuals are marked and released
Organisms left to resettle into habitat
Recapture individuals, noting no. marked and no. caught overall

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8
Q

The number of marked individuals in the second sample is proportional to…..

A

The number of individuals in the whole population

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9
Q

List the assumptions that MRR relies on.

A

Closed population
Marked individuals are an equal proportion of the population
Sample size remains constant
Marks do not influence organism negatively (predation)

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10
Q

Give some uses of population data.

A

Monitor ecosystem changes
Aid population management
Aid conservation models

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11
Q

State the equation that can be used to calculate population size.

A

B-D + I-E

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12
Q

What is population increase in an environment reliant on ?

A

Age of reproduction
Frequency of reproduction
Number of offspring
Reproductive lifespan

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13
Q

What does an age pyramid show ?

A

The changes in abundance from young to old

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14
Q

If the age pyramid is top heavy, the population is…

A

Declining

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15
Q

If the age pyramid is bottom heavy, the population is….

A

Increasing

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16
Q

How can we calculate the age of species ?

A

Using size, weight, colour changes, accumulation of chemicals, growth rings, cementum in teeth.

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17
Q

What does a survivorship curve show ?

A

The number of individuals surviving at each age in a species

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18
Q

What strategies will the survivorship curve reflect ?

A

K and R strategy species

19
Q

What does a life mortality table show ?

A

The probability of an organism of a particular age dying before reaching the next age class

20
Q

What is a period life table ?

A

Represents mortality rates during a specific time period of a certain population

21
Q

What is a Cohort life table ?

A

Representa the overall mortality rates of a certain population’s entire lifetime

22
Q

Why is a cohort life table more frequently used ?

A

It is able to make predictions on any expected change in mortality rates of a population

It also analyses patterns in mortality rates

23
Q

What does the abundance of different species in a population give us an insight into ?

A

The less visible aspects of a community

Competition and predation

24
Q

Smaller organisms are rarer, True or false ?

A

False, Bigger organisms are rarer

25
Q

What is the energetic equivalence hypothesis ?

A

Not all animals in a community share common energy source, energy available to larger animals is constrained by inefficient transfer of food.

26
Q

Why do generalist species tend to be more abundant than specialist species ?

A

Niche differences

Positive feedback between local abundance and regional distribution

27
Q

How do niche differences in generalised and specialist species affect abundance ?

A

Specialist species fill a highly specific and adapted niche, if conditions change will decline

Generalist species can exist in a wide range of habitats, Are able more able to adapt if conditions change

28
Q

Give the 2 factors that can alter habitats

A

Abiotic (temp and rainfall)

Biotic (predators, competition)

29
Q

What are core species ?

A

Generalist species

Large population and offspring
Limited habitat requirements
Able to extend habitat range

30
Q

What are the benefits of being a generalist species ?

A

Wide range

Enables continuous replacement of species if decline in one area.

31
Q

What are satellite species ?

A

Specalist species

Small population and offspring
Exacting habitat requirements
Struggle to extend range

32
Q

What are the disadvantages of being a specialist species ?

A

Restricted locally and less abundant

So more likely to go extinct

33
Q

What is distribution ?

A

How organisms are spatially arranged

34
Q

What is dispersal ?

A

The movement of individuals away from their area of origin or from centres of high population density.

35
Q

Give the 3 types of organism distribution.

A

Clumped, random and Uniform

36
Q

What is clumped distribution ?

A

When organisms clump around resources

Usually in habitats where resources are patchy

37
Q

Which distribution is more common ?

A

Clumped

38
Q

Why do organisms clump ?

A

To be close to resources
To remain in social and family units
To give protection and hide from predators.

39
Q

What is uniform distribution ?

A

When territorial species maximise the distance between themselves and their neighbours

To maximise space and resources

40
Q

Give an example of a species which uses uniform distribution.

A

Tigers and Plants
(spray urine)
(release toxins to prevent growth of other plants)

41
Q

What is Random distribution ?

A

When the position of each individual is independent

Occurs when species are homogenous (identical)

42
Q

Why is random distribution rare ?

A

as biotic and abiotic factors will greatly influence whether organisms cluster or spread apart.

43
Q

Give an example of random distribution.

A

Can occur in plants whose seeds are wind dispersed and in larvae who are distributed by currents.

Population Ecology (6 decks)

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