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ESS > Biodiversity > Flashcards

Biodiversity Flashcards

1
Q

What is biodiversity

A

“ biological diversity” - the variety of life on earth

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2
Q

Define habitat

A

A place where organisms live

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3
Q

Define community

A

A collection of all populations of species in an ecosystem

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4
Q

What is habitat diversity

A

The number of different habitats per unit unit area that are particular ecosystem/biome contains

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5
Q

Habitat diversity what this might lead to an increased of?

A

Genetic diversity
Species diversity

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6
Q

What is genetic diversity

A

The range of genetic material present in a gene pool or population of a species

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7
Q

Define gene

A

A section of DNA that is considered the basic unit of inheritance

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8
Q

Define gene pool

A

A collection of genes and the alleles with population

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9
Q

Why is a high genetic diversity important

A

Diversity is essential for survival

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10
Q

Define species

A

A group of organisms who share similar features who can inter breed to produce fertile offspring

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11
Q

Define endemism + example

A

An organism that is found in one place but nowhere else for example (lemurs are only found in Madagascar)

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12
Q

Define species diversity

A

The variety of species within a given area, habitat or region

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13
Q

What are the three aspects to biodiversity

A

Habitat diversity
Genetic diversity
Species diversity

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14
Q

What can we use to work out the species diversity of community or ecosystem

A

The Simpsons diversity index

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15
Q

What is the equation for the Simpsons diversity index

A

D = N(N-1)/sumn(n-1)

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16
Q

Define evenness

A

The relative abundance of a species (the number of individuals in a species)

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17
Q

Define species richness

A

The number of different species that are present

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18
Q

In the ecosystem there are five species and 20 animals. There are seven sparrows, six blackbirds, four hummingbirds, two doves and one pigeon. Calculate the species diversity of this ecosystem

A

7 - sparrow
6 - blackbirds
4 - hummingbirds
2 - doves
1 - pigeon

D = N(N-1)/sumn(n-1)
N(N-1) = (20)(19) = 380
sumn(n-1) = (7x6) + (6x5) + (4x3) + (2x1) + (1x0) = 86

380/86 = 4.42

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19
Q

What is a biodiversity hotspot

A

A hotspot is a region with a high-level of biodiversity that is under threat from human activities. Around 30 or recognised

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20
Q

Name three facts about biodiversity hotspots

A

– generally tend to be closer to the tropics
– cover only 2.3% of our globe
– 10 are in tropical rainforest

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21
Q

Name five biodiversity hotspots

A

– Japan
– New Zealand
– Philippines
– Caribbean islands
– corner of Africa

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22
Q

Name one positive and five negative of biodiversity hotspots

A

Positive:
– it is a useful model

Negative:
– focuses on vascular plants and ignores animals
– does not represent species diversity
– doesn’t consider genetic diversity
– does not consider the value of services (for example water resources)
– focuses on regions where habitats have already been lost, rather than the habitats that are being lost currently

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23
Q

What is evolution

A

The gradual change in species of a time that can take millions of years

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24
Q

What is natural selection

A

Nature selecting which individuals have the best features (the best adapted) for survival

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25
Q

What is artificial selection

A

Nature provides variation for humans select ones that are useful to them

26
Q

What are the seven stages in speciation

A

– Within a population of one species there is genetic variation
– individuals are isolated from the population to a new area with different selection pressures
– due to natural variation, some individuals will be better at surviving than others
– fitter individuals have an advantage and are more likely to survive
– these individuals reproduce and their offspring may inherit the advantageous gene
– those who do not carry these advantageous jeans maybe unlikely to survive long enough to reproduce
– this is why this process is called survival of the fittest because it leads to evolution by diversity and species overtime

27
Q

Name three examples of a geological barrier

A

– River
– mountain range (millions of years)
– clearing in a forest

28
Q

Explain the four step process of how geographic isolation can lead to 2 new species

A
  • At the start of the process there are no geological barriers so all individuals can reproduce with each another
    – mutations cause variation differences, so the species become better adapted to their environment
    – natural selection occurs when the individuals best suited to their environment survive and reproduce
    – when the geographical barrier is removed the populations colonise the area cannot reproduce as they are now different species
29
Q

What are selection pressures

A

The organisms that are better suited to their environment survive the pressure of selective agents. This is often referred to as ‘Survival of the Fittest’.

30
Q

Explain geographical isolation + example

A

When physical geographical barriers cause a population to split into two where mutations and natural selection occur to create two new species where the individuals in their species are best suited to their new environment. One example is the freshwater fish Char, which lives in lakes in Scandinavia, Switzerland and the UK. The population of this fish have been separated by the land between them meaning they can no longer interbreed

31
Q

Explain behavioural isolation

A

Behavioural isolation refers the fact that many species perform different mating rituals and this is a common barrier between animals.

For example certain species of crickets will only meet with males that produce a particular mating song

32
Q

Temporal isolation

A

When species that could interbreed do not because the different species breed at different different times. For example 2 different species of field crickets become sexually mature different seasons one in the spring and the other in autumn

33
Q

Explain ecological/ habitat isolation

A

This occurs when two species that could interbreed do not because the species live in different different areas. For example in India both the lion and tiger exist and are capable of breeding however the lion lives in grasslands and the tiger lives in the forest. The species live in different habitats and will not encounter one another is isolated from the other species

34
Q

Mechanical isolation

A

This is caused by structures that keep species isolated from one another. For example domestic dogs all belong to the same species. Dogs like the Chihuahua and the great Pyrenees hound would be unable to reproduce due to the difference in size

35
Q

Chemical isolation

A

This is caused by chemical barriers that keep the species isolated from one another. For example chemical barriers prevent gambits from forming. These chemical barriers will only allow sperm from the correct species to fertilise the egg

36
Q

Outline how the brown bear and the polar bear became two separate species

A

– A whole population of bears lived in one place originally
– a geological factors for example a mountain range or a river may have caused them to become isolated
– each new population has individuals that mutate for example mutation in their features
– natural selection chooses the better-adapted animal to survive and reproduce
– these animals reproduce and pass on the advantageous jeans to their offspring so that two different populations that differ so greatly that they can no longer breed even if the whole population comes together again

37
Q

What is speciation

A

The formation of a new distinct species in the course of evolution

38
Q

What is adaptive radiation

A

Adaptive radiation occurs through newly formed habitats (for example volcanic rock into a forest – primary succession) which can increase species diversity and/or genetic diversity in a population

39
Q

What is one example of adaptive radiation

A

Galapagos finches -> the to the new environments. Some of these adaptations included size, beak shape or core size this was all dependent on what was available in each area

40
Q

How can continental drift and plate tectonic theory contribute to adaptive radiation and speciation

A

As plates move they create geological barriers (for example: rivers, mountains, gorges, new islands), which can separate populations of organisms and dust create new species

41
Q

What is the background extinction rate

A

It is the natural extinction rate of all species

42
Q

What was the background extinction rate expected to be, and what is it currently?

A

It was estimated to be one species per species per year, however it is currently 100 to 1000 times more than that

43
Q

Which mass extinction are we in now

A

We are in the sixth mass extinction, this is called the Holocene

44
Q

What happens to the number of groups of organisms when there are mass extinctions

A

Wendy extinction rates peaks, there are drastic dips in the number of families

45
Q

Name three causes of mass extinction

A

– Overpopulation (the global population is expected to reach 9 billion by 2050))
– Global warming and climate change
– bio accumulation in individuals due to increased use of pesticides for agriculture

46
Q

Name a previous mass extinction

A

The KT extinction (cretaceous tertiary). This is the mass extinction of the dinosaurs

47
Q

Name two differences between prehistorical mass extinctions and current mass extinctions

A

Prehistorical disasters took over thousands or hundreds of thousands of years to take place, whereas the Holocene took over a few decades/hundreds of years. The Holocene occurs due to anthropogenic reasons, for example climate change due to the enhanced greenhouse effect, whereas prehistorical mass extinctions are not human-caused

48
Q

Distinguish between the mass extinctions evident in the fossil records and extinctions within historic times (4 mark question)

A

Fossil record extinctions occurred over relatively long time skills, whereas present-day extinctions occurred over short time skills (decades). Inked irons within historic periods are largely attributable to human causes, for example overhunting. Past mass extinctions are linked to natural courses, for example, meteorite impacts

49
Q

What is the Lincoln index + what assumption does it rely on?

A

The Lincoln index provides a way to measure population sizes of individual animal species which is related to capture-recapture methods.

It relies on the assumption that the proportion of marked animals in the second sample is the same as the proportion of marked to non-marked animals in a whole population

50
Q

What are four limitations of the Lincoln index?

A

Any 4 from:
– Capturing the animal may harm them or alter its behaviour
– the mark used may harm the animal, for example, toxic paint on an animal may harm them therefore tests need to be done prior
– marks may be removed before recapture accidentally
– Marks may make individuals less or more visible to predators/mates
– the method assumes that all animals in the population are equally catchable
– this method depends on open/systems. Usually, there are no closed systems therefore readings have to be taken over shorter time to reduce changes and pop size (in an open system individuals can migrate in and out of an area skewing results)
– trapping responses may vary: individuals being trap shy (avoiding the traps), or being trapped happy (individuals may go looking for the traps as they know it is an opportunity for food)

51
Q

Does trap shyness or trap happiness lead to an overestimation or underestimation

A

Trap shyness leads to an overestimation, whereas trap happiness leads to an underestimation

52
Q

Name at least five factors that make specific animals more prone to extinction than others

A

Any five from:
– Natural disasters
– deforestation
– monoculture
– overfishing
– urbanisation
– altering habitat shape
– pollution (air and water)
– captivity
– antibiotics/battery farming

53
Q

What three factors help to maintain biodiversity

A

– Inertia
– limiting factors
– stage of succession

54
Q

What is inertia

A

The property of an organism to delay or resist change when certain factors change

55
Q

What are limiting factors

A

If the abiotic factors are in abundance the system can survive longer even if one is reduced

56
Q

Why are later stages of succession better to maintain biodiversity

A

Later stages are more resilient and stable than younger ecosystems because they have more niches, therefore if one organism dies, another can take its role. This is because of the complexity of ecosystems in the later stages will have more complex food webs

57
Q

Name three causes of reducing biodiversity in tropical rainforest

A
  • deforestation
    – logging and ranching
    – shifting cultivation
58
Q

What is shifting cultivation

A

where the land is cleared and the vegetation burnt, crops are grown for a few years until yields decline due to decreasing fertility of the soil. The farmers then move on to a new clearing

59
Q

What is ranching

A

Clearing hectares of forest to create ranches.

60
Q

Name three effects of reduced by diversity and tropical rainforest

A

– Production of habitats
– fewer abundance of ecological niches
– lower rates of biomass and photosynthesis

61
Q

Outline the ways in which natural selection leads to biodiversity (4)

A

– natural selection occurs when a population of individuals has adapted better to selection pressures
– they are more likely to reproduce and pass on advantageous alleles to their offspring
– this will increase allele frequency and genetic diversity
– more niches will be created and overall a new and better-adapted species

62
Q

Explain the road that plate activity has in the diversity of an ecosystem (3)

A

– When plates converge, this forms new land. this creates natural barriers such as mountain ranges
– another example is when plates diverge creating gorgeous or river forms
– there are now new selection pressures in different environments
– organisms that have adapted successfully pass on their alleles, increasing genes diversity and speciation

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