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Module 6- Genetics and ecosystems > 6.6 Population and sustainability > Flashcards

6.6 Population and sustainability Flashcards

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Biology 101 flashcards
1
Q

Define carrying capacity?

A

Carrying capacity- the maximum population size that can be maintained over a period in a particular habitat.

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2
Q

Define limiting factor?

A

Limiting factor- the factor whose magnitude slows down of a natural process.

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3
Q

What is point ‘a’ called? What is happening here?

A

A= The lag phase.

There may only be a few individuals, which are still acclimatising to their habitat. At this point, the rate of production is low, and growth of the population size is low.

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4
Q

What is point ‘b’ called? What is happening here?

A

B= The log phase

Resources are plentiful, and conditions are good. Reproduction can happen quickly, with the rate of reproduction exceeding mortality. The population size increases rapidly.

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5
Q

What is point ‘c’ called? What is happening here?

A

C= The stationary phase

The population size has levelled out at the carrying capacity of the habitat- the habitat cannot support a larger population. The reproduction and mortality are equal. The population size stays stable or rises and falls slightly depending on environmental conditions.

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6
Q

What 2 types of limiting factors can you have in terms of population size?

A
  • Density dependent limiting factors
  • Density independent limiting factors
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7
Q

What spots a habitat being able to support a larger population?

A

Limiting factors.

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8
Q

What are density independent limiting factors?

A

These limiting factors act just as strongly, irrespective of the size of the population. e.g.particularly low temperatures may kill the same proportion of individuals, irrespective of it’s size.

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9
Q

What are density dependent limiting factors?

A

Factors that influence the population more strongly as the population size increases. e.g. the availability of resources like food, water, light ect.

Also, as population size increases, levels of parasitism and predation from other species also increase, as with competition.

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10
Q

What are the 2 types of strategists?

A

r- strategies and k-strategies. These represent 2 ends of a continuum of strategies adopted by living things.

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11
Q

What animals are k-strategists? what are their characteristics?

A

K-strategists, such as birds, larger mammals and larger plants show the some of the following characteristics:

  • low reproductive rate
  • slow development
  • late reproductive age
  • long life span
  • large body mass
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12
Q

What animals are r-strategists? what are some of their characteristics?

A

r-strategists, such as mice, insects, spiders and weeds, tend to exhibit many of the following characteristics:

  • high reproductive rate
  • quick development
  • young reproductive age
  • short life span
  • small body mass
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13
Q

What sort of species sizes is determined by the carrying capacity?

A

k-strategists.

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14
Q

What has a large effect on the population size of k-strategists?

A

Limiting factors have a significant effect on k-strategists as the population size gets closer to the carrying capacity, it causes the population size to gradually level out.

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15
Q

What is unique to r-strategists?

A

In these species, the population size can increase so quickly that it can exceed the carrying capacity of the habitat before the limiting factors start to have an effect. |Once the carrying capacity has been exceeded, there is no longer enough resources to allow the individuals to reproduce or survive. This is know as a boom or a bust.

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16
Q

What is a boom in terms of a r-strategists?

A

When the population size increases so quickly that it exceeds the carrying capacity of the habitat before the limiting factor starts to have an effect.

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17
Q

Apart from running out of resources, what can r-strategists also experience during a boom?

A

Excessive build up of waste products may start to poison the species, causing them to die, entering a death phase.

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18
Q

What is the most important influence on population growth?

A

The most important influence on population growth is the physical rate at which individuals can reproduce.

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19
Q

Why is the rate a species can reproduce important for their population size?

A

Quick population growth means pioneer r-strategists species colonise a disrupted habitat before k-strategists, dispersing to other habitats once limiting factors start to have an effect.

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20
Q

Describe what is happening in this graph?

A

This graph shows the boom/ bust of an r-species. ‘a’ shows where the boom is happening and ‘b’ is the carrying capacity.

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21
Q

What is interspecific competition?

A

Competition between individuals of different species.

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22
Q

What is intraspecific competition?

A

Competition between individuals of the same species.

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23
Q

Explain what is happening in this graph.

A
  1. When the predator population gets bigger, more prey are eaten.
  2. They prey population gets smaller, leaving less food for the predators.
  3. With less food, fewer predators can survive and their population size reduces.
  4. With fewer predators, fewer prey are eaten, and their population size increases.
  5. With more prey, the predator population gets bigger, and the cycle starts again.
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24
Q

What are the two types of competition?

A
  • Intraspecific competition
  • Interspecific competition
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25
Q

What happens during intraspecific competition?

A

Factors such as food become limiting. Those individuals best adapted to obtaining food survive and reproduce, while those not so well adapted fail to reproduce, or die. This slows population growth and the population enters the stationary phase.

26
Q

What does interspecific competition affect?

A

Interspecific competition can affect both population size of a species, and the distribution of a species in an ecosystem.

27
Q

What was the scientist Gause’s work focused on?

A

Interspecific competition

28
Q

What did the scientist Gause do?

A

He grew 2 species of paramecium, both separately and together. When together, there was competition for food, with P. aurelia obtaining food more efficiently that P. caudatum. Over 20 days, the population of P. caudatum reduced and died out, whereas, the population of P. aurelia increased and became the only species left.

29
Q

What were the 2 types of Paramecium called in Gause’s experiment?

A
  • P. caudatum
  • P aurelia
30
Q

What did Gause conclude from his experiment?

A

Gause concluded that more overlap between 2 species’ niches results in more competition. If 3 species have the same niche, one is out competed by the other, causing it to die out or significantly reduce in numbers. 2 species in the same habitat cannot occupy the same niche. This is known as the competitive exclusion principle.

31
Q

What is the competitive exclusion theory?

A

The idea that 2 species in the same habitat cannot have the same niche. This can be used to explain why particular species only grow in particular places.

32
Q

What is different about how animals behave in a lab compared to in the wild in Gause’s expaeriment?

A

In a laboratory it is easy to exclude the effects of other variables, so the habitat of the 2 species remains stable. In the wild however, a wide range of variables can become limiting factors- the growth of different populations may change daily.

33
Q

Define conservation?

A

An active management process involving human innervation.

34
Q

Define preservation?

A

Maintenance of habitats and ecosystems in their present condition, minimising human impact. (passive process)

35
Q

What does conservation include?

A

It includes maintaining diversity between species , genetic diversity within species and maintaining a range of habitats and ecosystems.

36
Q

In what ways is biodiversity threatened by the increasing human population?

A
  • Over exploitation of wild populations for food.
  • Habitat distribution and fragmentation as a result of more intensive agricultural practices, increased pollution, or wide spread building.
  • Species introduced to an ecosystem by humans that out-compete other native species, leading to their extenction.
37
Q

What must successful conservation be considerate of?

A

Must be considerate of:

  • social and economic costs to the local community.
  • effective education and liaison with the community.
38
Q

What are some examples of conservation?

A
  • National parks
  • Green belt land
  • Specific scientific interest (SSSIs)
  • Legal protection to endangered species
  • Zoos
  • Botanic gardens
39
Q

What are some examples of management strategies for conservation?

A
  • Raise carrying capacity by providing extra food.
  • Move individuals to enlarge populations, or encourage natural dispersion of individuals between fragmented habitats.
  • Restrict dispersal of individuals by fencing.
  • Control predators and poachers.
  • Vaccinate individuals against disease.
  • Preserve habitats by preventing pollution or distribution.
40
Q

Why do conservationists think humans have an ethical responsibility to look after habitats?

A

They believe that every species has a value.

41
Q

What are human activities that work against conservation lead by? Give some examples.

A

They are driven by economics. e.g. burning fossil fuels, open cast mines ect.

42
Q

What are some economic reasons for conseravtion?

A

Many species have economic value when harvested.

  • Many plant and animal species provide a valuable food source.
  • Many drugs we use are sourced from the environment.
  • Natural predators of pests can act as biological control agents.
43
Q

What are some species that contribute indirectly to the economic reasons for conservation?

A
  • insects pollinate crops, without them a harvest may fail.
  • Other communities are important in maintaining water quality, protecting soil and breaking down waste products.
44
Q

What is an economic and social reason for conservation?

A

Ecotourism and recreation in the countryside.

45
Q

What is a good way to manage small scale timber production?

A
  • Coppicing
  • Pollarding
46
Q

What is coppicing?

A

It’s a was of managing small scale timber production. The stem of a deciduous tree is cute close to the ground. Once cut, it grows new shoots from the cut surface and mature into narrow narrow stems. After they’re cut new shoots start to grow and the cycle continues.

47
Q

What can coppicing be use for?

A

Once cut, new shoots mature into narrow stems. these can be used for fencing, firewood or furniture.

48
Q

What is pollarding?

A

Pollarding is similar to coppicing but the stems are cut higher up to prevent deer eating the emerging shoots.

49
Q

How do woodland managers provide a consistent supply of wood?

A

They divide a wood into sections and cut one section every year- this is rotational coppicing.

50
Q

Why does rotational coppicing work?

A

As only one section is cut every year, by the time they want to coppice the first section again, the new stems have matured and are ready to be cut. In some sections, trees are left to grow larger without being coppiced- these trees are called standards, and are harvested to supply larger bits of wood.

51
Q

Why is rotational coppicing good for biodiversity?

A

If woodland is left unmanaged, it will go through succession, blocking out light to the woodland floor and reducing the number of species growing there. In rotational coppicing, different areas of woodland provide different habitats, increasing the biodiversity.

52
Q

What affect does clear felling have on the habitat?

A
  • Felling all the trees in one area
  • Destroys habitats
  • Reduces soil mineral levels
  • Leave soil susceptible to erosion
  • Soil may run off in to waterways, polluting them.
53
Q

What is clear felling an example of?

A

large scale timber production.

54
Q

What principles does modern sustainable forestry working on?

A
  • Any tree which is harvested is replaced by another tree.
  • The forest as a whole must maintain its ecological function regarding biodiversity, climate, and mineral and water cycles.
  • Local people should benefit from the forest.
55
Q

What is a way of sustainable large-scale timber production?

A

Selective cutting.

56
Q

What does sustainably managing forest involve?

A

Balancing conservation against the need to harvest wood, both maintain biodiversity and make the woodland pay for itself.

57
Q

How can we work to harvest fewer trees?

A
  • Control pest and pathogens.
  • Only plants particular tree species where they know they will grow well.
  • Position trees an optimal distance apart- if too close, this causes too much competition for light, and they will grow tall and thin, producing poor quality timber.
58
Q

What tree principles have The Marine Stewardship Council proposed for sustainable management of fisheries?

A
  • Fishing must take place at a level which allows it to continue indefinitely- the optimum is to maintain fish populations at the carrying capacity of their environment- therefor, no over fishing.
  • Fishing must be managed to maintain the structure, productivity, function and diversity of the ecosystem- there must not be permanent damage to the habitat.
  • Fisheries must adapt to changes in circumstances and comply with local, national and international regulations.
59
Q

What can be done to priovide sustainable fish stocks?

A
  • Flowing the 3 principles proposed by the marine stewardship council.
  • Aquaculture.
60
Q

What is aqua culture?

A

Farming of aquatic organisms.

61
Q

How does aqua culture provide sustainable fish stocks?

A

raising sticks of fish in aquaculture restricts the impact on oceanic fish stocks.

Module 6- Genetics and ecosystems (6 decks)

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