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Population Ecology > Week 6 - 8 > Flashcards

Week 6 - 8 Flashcards

1
Q

What 5 things can models be used for

A

Understanding population growth, equilibrium, limitation, regulation and persistence

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2
Q

What is the philosophy behind a model

A

it is an idealised form of a system

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3
Q

What two factors make a strong model

A

High in both biological understanding and empirical strength

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4
Q

Assumptions of logistic population growth

A

Carrying capacity is constant
Age structure does not affect growth
No genetic structure
Birth and death is linear to N
Carrying capacity has an instant effect– no time lags
Density crowding affects all individuals equally

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5
Q

Why does exponential growth not occur and what kind of models can be used instead

A

Other interactions curb growth such as disease, competition and predation so dynamic or multi-species models can be used

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6
Q

What shape is a density dependent growth

A

Population size has negative linear feedback– logistic growth

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7
Q

What is allee effect

A

When there is a positive population size or density and mean individual fitness

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8
Q

example of single species logistic growth

A

In Gause’s famous experiment, Paramecium caudatum, bursaria and aurelia all showed logistic growth; their density was dependent on the space and the food source

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9
Q

Potential example of exponential growth

A

Human population growth does not yet appear to be density dependent

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10
Q

Basic logistic growth models are flawed, what do they need to account for

A

Intra and inter generational interactions and age structure (turtles and sawtoothed grain beetles)
Time lags
Non-linear relationship between B&D and N (allee effects - guillemots)
Sex ratios and interactions with the environment (Gouldian finches)
Intra and inter sex interactions

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11
Q

Where can intraspecific interactions occur

A 
Within generations (siblicide, more related to yourself)
between generations (conflict between offspring wanting investment, and parent wanting more offspring)
within sexes (male:male competition)
between sexes (females being harassed)
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12
Q

What is the relationship between current fecundity and future survival

A

The less you invest in current fecundity, the more you can invest in future survival

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13
Q

What is population viability analysis

A

Set of analytical and modelling approaches
to assess the future course and risk of extinction in a population which can accommodate genetic demographic and environmental stochasticisty

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14
Q

Types of stochasticity that can influence populations

A

genetic demographic and environmental

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15
Q

What is a deterministic model

A

where the output of the model is fully determined by the parameter values and the initial conditions. e.g B,D,I, and E constant over time,

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16
Q

What is a stochastic model

A

models which possess some inherent randomness.
The same set of parameter values and initial
conditions will lead to an ensemble of different
outputs

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17
Q

What is demographic stochasticity

A

describes the randomness
that results from the inherently discrete nature of
individuals individuals. It has the largest largest impact on small populations.

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18
Q

What is environmental stochasticity

A

describes the randomness
resulting from any change that impacts an entire
p po ulation (such as changes in the environment). Its
impact does not diminish as populations become large.

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19
Q

How can genetic stochasticity lead to evolution

A

i) founder effects and genetic drift
ii) non-random assortment during reproduction
iii) inbreeding

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20
Q

What is a minimum viable population

A

Lowest population size for survival
– Space for stochasticity
– Space for genetic effects
•For a set period of time

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21
Q

What are the two overall reproductive strategies

A

r and K

22
Q

What 2 parameters characterise a logistic growth curve

A

r and K

23
Q

3 Ways in which individual species models can be applied

A

Pest management
– Conservation management & reintroductions
– Harvesting (Brown bears)

24
Q

4 types of predator and prey cyle

A

Stable limit cycles
Stable point cycles
Unstable cycles
Extinction

25
Q

In pred prey cycles, what does the term stable mean

A

Where a pair of populations
(predator, prey) which have a
return tendency to a particular
density

26
Q

In pred prey cycles, what does the term cycle mean

A

Regular, identifiable pattern of population

sizes over time

27
Q

What are the characteristics of a stable limit cycle

A

Both pred and prey go through predictable cycle
Predator lags behind prey
Population never reaches equilibrium

28
Q

What are the characteristics of a stable point cycle

A

Both pred and prey populations settle at a fixed number
No or tiny oscillations of populations,
Can occur through dampened oscillation

29
Q

When do unstable cycles occur

A

If it its a new cycle, sometimes the dynamics start this way then
become stable
Common when there is more than 1 ped or prey

30
Q

What could happen if a predator is introduced to a new ecosystem

A

most introductions lead to their extinction
Can destabilise the ecosystem
Or over evolutionary time, c coexist and form stable limit or cycles

31
Q

What are some limitations to predator prey cycles

A

Prey tend to have a refuge away from predators
Models assumes predation is random which it rarely is
Models assume similar generation time between predators and prey which is rarely true
Predators may be generalists and prey switching tends to stabilise populations.
Most cycles tend to be found in northern temperate regions, tropics are unknown

32
Q

What is competition

A

Two or more species using the same limited resource to the detriment of both ie reciprocally negative interaction

33
Q

2 types of competition

A

Consumptive competition

Interference competition

34
Q

What are the types of consumptive competition

A

Scramble - occurs over a resource that is accessible to all competitors (that is, it is not monopolizable by an individual or group).
Exploitative

35
Q

What interference competition

A

occurs directly between individuals via aggression

36
Q

The greater the niche overlap, the greater the..

A

competition

37
Q

What is the density dependent logistic growth model

A

dN over dt = rN(K-N over K)

38
Q

What are the 3 outcomes of inter-specific competition

A
  1. Both species coexist
  2. Species 1 becomes extinct
  3. Species 2 becomes extinct
39
Q

How can competiting species coexist

A

– Resource partitioning (species use resources

somewhat differently – temporal, spatial)

40
Q

What is a fundamental niche

A

N-dimensional space where
species can survive & reproduce indefinitely,
includes environmental and behavioural conditions

41
Q

What is character displacement

A

A rare phenomenon when species under selection to evolve niche dimensions with lower overlap. It leads to evolution of physical
characteristics among competitors that reflects more specialised role in
ecosystem

42
Q

What is indirect competition

A

defined as conflict of one organism or species on another that is mediated or transmitted by a third. e.g predators both eating the same prey

43
Q

In what areas can niche displacement take place

A

Character
Space
Niche

44
Q

When may competitive ability evolve

A

evolve if the food web is

complex and no avoidance is possible

45
Q

How can can predators control populations in a non lethal way

A

By creating a landscape of fear resulting in prey from reproducing as optimally as they avoid certain areas and spend more time being vigilant

46
Q

What types of information can prey use to detect predators

A

Public - e.g acoustic/olfactory/visual cues

Private

47
Q

What non lethal effects

A

Affects:
– population number
– behaviour
– distribution

48
Q

What is private information

A

information which is known to the individual only (e.g., their own nesting history),

49
Q

What is public information

A

Information available to everyone l (e.g., abundance of predators at a site)

50
Q

What is the primary cause of songbird nest failure

A

Ricklefs 1969 said it to be predation

51
Q

What is a win–stay, lose–switch strategy

A

The situation in which birds
continue to use similar nest-sites after nest success but
select different nest-site characteristics after failure

52
Q

What is a stay–stay strategy

A

, choosing nest-sites irrespective of nest

fate

Population Ecology (5 decks)

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