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Population Ecology > Week 2-5 > Flashcards

Week 2-5 Flashcards

1
Q

What is a population?

A

A discrete group of individuals from a single species in a relatively self contained space, where there is little immigration and emigration relative to the intentional rates of recruitment and mortality

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2
Q

What increases population isolation (i.e decrease in immigration and emigration)

A

Geographical barriers such as rivers and mountain ranges, as well as habitat fragmentation cause by deforestation.

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3
Q

Why do populations generally have the same gene pool?

A

Because populations tend to be isolated and thus can not move breed with other individuals from a different population

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4
Q

What can regulate population size?

A

Habitat size, quality, fragmentation
predator population
competing species
climate/optimal conditions

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5
Q

What is the difference between population size and population density?

A 
size = total number
density = number per unit of space
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6
Q

What is a fundamental niche?

A

is the combination of environmental conditions and resources where a species COULD survive and reproduce

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7
Q

What is a realised niche?

A

Is the area of the fundamental niche where a species actually exists after interacting with other species and being out competed from some regions

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8
Q

What determines the limits of the geographic ranges?

A

Abiotic/biotic factors that prevent further spread
Human transformation of the landscape e.g farming, deforestation
Local population dynamics at the edge of the range
Genetic mechanisms

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9
Q

How can knowledge in population ecology apply to the real world

A 
Conservation of endangered species
Harvesting/management of natural resources
Invasive species biology
Pest control
Spread of diseases
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10
Q

Which region hold the highest level of biodiversity

A

Tropical

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11
Q

What did the Millennium Ecosystem Assessment say about tropical forest

A

It said that habitat change has placed a very high stress on tropical forest and unless anything is done the impact of this stress will rapidly increase

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12
Q

How much of the Atlantic Forest has been lost`

A

95%

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13
Q

How much the Mediterranean and temperate did Millennium ecosystem assessment
say are lost

A

70%

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14
Q

How much semi-natural habitats in the UK have been lost since 1940 on average

A

70%`

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15
Q

Give an example of a location, with time period, which has suffered fragmentation and a quantified amount of loss

A

Heathland Dorset: 1759 – 1978 (86% loss)

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16
Q

What is the relationship between landscape structure, population dynamics and ecological processes

A

Landscape structure can affect the other two

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17
Q

What is the species-are realtionship

A

It is the positive relationship between the size of an area and the number of species found within it

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18
Q

Why is the species relationship positive

A

Large areas tend to have more niches which different species can in habit
Isolation is more likely to occur in large areas and so speciation is more likely to occur.

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19
Q

What were the main findings of Ferraz et al. (2003)

A

A 10-fold decrease in the rate of species loss requires a 1,000-fold increase in area. Fragments of 100 hectares lose one half of their species in <15 years, too short a time for implementing conservation measures.

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20
Q

What is the impact on fragmentation on different species of bird

A

Different species have different tolerance levels to fragment size e.g blackbirds reached 100% breeding probability in woods less than 1ha but marsh titis needed over 15ha to reach 100% breeding probability

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21
Q

What aspects of population dynamics does landscape structure affect

A 
Dispersal + colonisation
Persistence
Productivity
Synchrony
Gene flow
Spatial density dependence
Buffer effects
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22
Q

Which ecological processes does landscape structure affect

A

Predation, herbivory, pollination

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23
Q

example of pollinator being affected by fragmentation and by who

A

Euglossa sp. abundance fell as fragment size decreased Powell and Powell (1987)

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24
Q

example of plant reproductive success being affected by fragmentation and by who

A

In Sweden the mean number of seeds set per flower of maiden pinks were lower in fragmented habitats than continuous
due to a 2-3 fold decrease in pollinator visitation (Jennersten 1988)

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25
Q

What are the potential consequences of fragment caused changes in pollinators

A

Fragmentation can restrict pollen flow which may reduce both the genetic variability or progeny and the effective genetic neighbourhood size which in turn increases the risk of inbreeding depression and changes in long term stability of isolated populations

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26
Q

What is the overall change in biodiversity distribution and who stated it

A

Moving poleward: in Britain 275 out of 329 species have shifted northward. Hickling et al 2006

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27
Q

Define trophic cascade

A

Trophic Cascade is the theory that food webs are controlled by a top-down process, where top predators affect the abundance or behaviour of their prey, which then has impact on the next lower tropic level.

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28
Q

What is shifting baseline theory

A

Refers to how, with each generation, the accepted norm for ecological conditions lowers since each generation lacks the historical knowledge of how that environment used to be.

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29
Q

Example of shifting baseline theory and by who

A

Pauly (1995) observed that there was a gradual accommodation for the disappearance of fish species and how each gen. of fishery and marine scientists assume that the current fish populations are the norm

30
Q

What is the Hutchinson niche

A

It is an “n-dimensional hypervolume”, where the dimensions are environmental conditions and resources, that define the requirements an individual/species needs in order to survive. The “hypervolume” defines the multi-dimensional space of resources (e.g., light, nutrients, structure, etc.) available
to be used by the organism under consideration

31
Q

What’s an advantage to the Hutchinson niche model

A

niche can be measured, mathe­matically manipulated and represented in climo-graphs.

32
Q

What is a meta-analysis

A

the statistical procedure for combining data from multiple studies

33
Q

How can a meta-analysis be used

A

can be used to identify common effects and analyse consistency between studies

34
Q

5 stages of a systematic review

A 
Defining question
Finding the data
Summarising relevant data
Assessing the quality of the data
Analyse and combine the data
35
Q

Example of the effect fragmentation has on seed predation and by who

A

Burkey 1993 found seed predation to be lower at than the interior.

36
Q

What are the consequences of fragmentation affecting seed predation

A

Seedlings at the edge are less likely to be eaten and thus more likely to survive to germination, however this may be offset by an adverse micro climate.
Also it may lead to changes in spatial heterogeneity and survivor ship of the host plant of the seed predator

37
Q

Example of how decomposes are affected by fragmentation

A

Klein 1982 found that as the no. of dung beetle species went down, so did the rate of dung decomposition with increasing fragmentation.

38
Q

What are the potential consequences of fragmentation affecting decomposers and who suggested them

A

Potential implication for habitat productivity and the flow of nutrients through an ecosystem since the rate of decomposition has a positive linear relationship with nitrogen and phosphorus concentrations. Enríquez 1993

39
Q

What impact has climate had on marine environments and range shifting (cite)

A

Perry et al 2005 found that the North Sea winter bottom temp. has increased by 1.6 Celsius in 25 years. There has also been poleward shifts in distributional ranges of some marine species with an average rate of 22km per decade

40
Q

Evidence for climate caused changes in phenology

A

Parmesan and Yohe 2003 conducted a meta anaylsis on 677 species and found that over a range of 16-132 years, 62% showed trends towards spring advancement e.g earlier frog breeding, bird nesting, first flowering, tree budburst, arrival of migrant birds and
butterflies

41
Q

How can climate warming change phenologies generally

A

It can cause earlier springs, later autumns and increased vegetation activity

42
Q

Describe Keenan et al. 2013 ‘s experiment

A

Over 20 year they assessed changes in phenology of temperate forest in eastern US

43
Q

What did Keenan et al. 2013 find after their study

A

They found that carbon uptake through photosynthesis was more than carbon release through respiration.

44
Q

What are the implications of Keenan et al 2013

A

It suggests current and future increase of carbon uptake due to changes in phenology and since this process is a negative feedback loop it could slow down the rate of warming

45
Q

What is a consequence to changes in phenology

A

Can lead to trophic mismatch

46
Q

Example of a trophic cascade

A

A study conducted by Waser et al 2014 in the Elk Mountains, Colorado found that the coyotes avoided a biological research centre due to the high human activity. Since coyotes often feed on the fawns, the does favour these areas and thus the grazing intensity increased the closer one was to the station. This in term affected the seedling recruitment of blue combine and scarlet gilia flowers, which was significantly lower by the station than away where coyotes activity was higher

47
Q

Example of trophic mismatch and by who

A

Doiran at al 2015 studied the effects of warmer springs on greater snow geese. Warmer springs and earlier snow melt caused the peak nitrogen, an index of the nutritive value in plants, to hit earlier. This resulted in a mismatch between peak nitrogen in the plants and the hatch dates of the geese which had not shifted to earlier in the year. Consequently gosling body mass and structural size at fledging were lower when the mismatch was greater, and thus the fitness of geese was negatively affected. One can presume that this will get worse as warming continues

48
Q

What does the millennium ecosystem assessment say about over exploitation

A

Overexploitation has a significant impact on biodiversity loss, particularly in marine and tropical biomes

49
Q

What figures did WWF provide for the wildlife population decline between 1970 and 2010

A

79% of freshwater, 39% terrestrial species, 39% marine species have declined between 1970 and 2010

50
Q

What happens carrying capacity of the environment is exceeded

A

The environment becomes degraded and the final carrying capacity may end up being lower than the original. Also, the loss of species can lead to trophic
cascades that decrease the carrying capacity of the environment for other species

51
Q

What is the symbol for carrying capacity

A

K

52
Q

What characteristics do K-strategist species typically have

A 
Stable environment
Large body size
Long life expectancy
Late maturation
High parental care Fewer offspring
53
Q

What give K-strategists their name

A

they are species whose population fluctuate at or near the carrying capacity of the environment they live it

54
Q

What gives r-strategist their name

A

They are species whose populations are governed by their maximum reproductive capacity.

55
Q

What characteristics do r-strategist species typically have

A
  • Unstable environment
  • High fecundity
  • Small body size
  • Early maturation
  • Short generation time
  • Dispersed offspring
56
Q

Define MSY

A

Maximum sustainable yield is the number of weight of a species that can be removed from the stock of animals without impacting the long-term stability of the population

57
Q

Describe the sustainable yield curve (graph)

A

the x-axis is fishing effort or fishing mortality, y-axis is yield. The sustainable yield curve begins at the origin and increases. However, the rate of increase decreases until it plateaus. This is the MSY and when a stock is fully fished. If effort or mortality continues to increase, the yield decrease at an increasingly faster rate until the stock is depleted

58
Q

How is the MSY derived from our knowledge of logistic growth

A

Is a population is assumed to be following logistic growth the MSY will be exactly half of the carrying capacity of the species as this is the stage at which the population growth is the highest

59
Q

Why is it important to understand population density

A

It is key to the
management of natural populations (e.g.
conservation or sustainable exploitation)

60
Q

What is a ‘close’ population

A

a population with no immigration or emigration

61
Q

What are the two equations used to represent population density in a close population

A 
Nt= B-D and 
Nt+1= Nt+B-D
62
Q

Why are abiotic factors density-independent and give examples

A

Because they regulate population but aren’t affected by population density.
e.g. Weather and stochastic environmental events (e.g. fire,
flood, drought, habitat destruction, spraying of pesticides)

63
Q

What is the relationship between population density, mortality rate and fecundity decreases

A

Usually, the denser a population is, the greater

its mortality rate and fecundity decreases.

64
Q

When do density-dependent processes occur

A

when population growth rates are regulated by the density of a population (e.g. competition for mates, competition for resources, diseases, increased predation)

65
Q

How does low prey density affect predators

A

Low prey density increases the mortality of its predator because it has more difficulty locating its food source

66
Q

Examples of different types of density-dependent processes

A

competition for mates, resources, diseases, increased predation

67
Q

Describe the relationship between population density, mortality rate and fecundity

A

As density goes up, mortality rate goes up and fecundity goes down

68
Q

Describe and explain the relationship between population density and intrinsic rate of increase

A

As population density increases, the intrinsic rate of increase decrease as the are less resources and disease spread is faster

69
Q

What age should one focuses on conserving an r-strategy species and why

A

The focus should be on the older as they produce lots of young since their is a high chance many wont survive

70
Q

Example of a positive density dependent effect on growth rate

A

The Allee-effect (Allee 1931) is when population growth rate is very low in a low density population as there is a low chance of finding a mate, which increases as density increases.

71
Q

Example of positive density dependence other than Allee effect

A

Insects may be attracted to dense patches of a flowering plant species and pollinate them efficiently, but ignore sparse stands.

Population Ecology (5 decks)

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