Topic 3

Question 1

what are the 3 forms/types of biodiversity?

Answer 1

species diversity
habitat diversity
genetic diversity

Question 2

what is biodiverstiy?

Answer 2

number of species in an area and their relative abundance that can be measured by: species, habitat, and genetic diversity

Question 3

what is species diversity?

Answer 3

in communities it’s a product of 2 variables: no. species (richness) AND their relative proportions (evenness)

Question 4

what is habitat diveristy?

Answer 4

refers to a range of different habitats in an ecosystem or biome

Question 5

what is genetic diversity?

Answer 5

refers to the range of genetic material present in a population of species

Question 6

how can biodiversity be measured?

Answer 6

through the use of diversity indices
eg. using quadrats OR mark release recapture methods
to analyse data you can use:
- lincoln index for mark release recapture
- simpson diversity index -> number of species & their relative abundance -> higher number means more diverse

Question 7

what could low biodiversity indicate?

Answer 7

• presence of humans/urbanisation -> pollution
• habitat doesn’t have enough resources to support wide range of different species/niches
• early stages of succession
• eutrophication in ponds

Question 8

why is it important to measure and quantify biodiversity?

Answer 8

• for conservation efforts so that areas of high biodiversity can be identified, explored, and appropriate conservation can be put in place where possible
• for comparing similar communities > eg. low diversity could be indicative of pollution, eutrophication, or recent colonisation of a site
• to assess any changes to biodiversity in a given community over time
  -> which is important and useful when assessing the impact of human activity on that community

Question 9

what are the origins of biodiversity? (ie. how has biodiversity arisen?)

Answer 9

biodiversity arises from evolutionary processes - natural selection

Question 10

what is evolution?

Answer 10

a gradual change in the genetic character of populations over many generations, achieved largely through process of natural selection

Question 11

how has biological variation arisen? how can this variation affect an individual?

Answer 11

• it has arisen randomly through random mutations
• the variation can be beneficial to, damaging to, or have no impact on, the survival of the individual

Question 12

what is the process of natural selection?

Answer 12

• there is genetic diversity/variation within a population of one species, which is caused by mutations and sexual reproduction
• due to this natural variation, some individuals will have an increased chance of survival - if the variation is beneficial
• better adapted individuals survive to reproduce more successfully and pass beneficial genes to offspring
• over time, beneficial genes are selected again and again until all individuals have that beneficial characteristic
• examples: giraffes and long necks, antibiotic resistant bacteria

Question 13

what is speciation?

Answer 13

• formation of a new species when populations of a species become isolated and evolve differently from other populations
• occurs over long period of time

Question 14

how can populations become isolated? (2 ways)

Answer 14

• isolation caused by environmental changes that can form geological barriers
  -> mountain formation, sea level change, climatic change, tectonic plate movements
• also be reproductive barriers -> eg. different mating patterns/behaviours

Question 15

how has tectonic plate movement/activity influenced evolution and biodiversity?

Answer 15

• about 250 mil years ago: all land was one supercontinent named Pangea
• tectonic plate movement over time (due to convections currents in mantle) split Pangea eventually into 7 present-day continents
• splitting caused isolation through geographical barriers (eg. oceans, mountain ranges) prevented populations from interbreeding, which led to speciation & increase in biodiversity
• specific case studies:
  *separation of Australia: isolated species living there, preserving distinctive flora + fauna ALSO indo-australian plate moved through different climates therefore australia’s climate became hot&dry, leading to evolution of drought resistant species
  *land bridge between siberia and alaska: caribou and reindeer are quite similar as result

Question 16

what factors have caused mass extinctions in the past?

Answer 16

• tectonic plate movement
• super-volcanic eruptions
• climate changes -> droughts and ice ages
• meteorite impact

Question 17

how do mass extinctions link to biodiversity?

Answer 17

• mass extinctions allow new pathways/directions for evolution
• eventually increases biodiversity
• eg. dinosaurs died, made way for mammals
• short-term loss in biodiversity for long-term gain

Question 18

describe the current rates of species loss. what are the human activities that cause species extinction? (refer to the background extinction rate when describing the current rates of species loss)

Answer 18

• far greater now that in past due to increased human influence
• human activities that cause species extinction:
  habitat destruction
  introduction of invasive species
  pollution
  practices of agriculture
  overharvesting and overhunting
  (HIPPO)
• background extinction rate is 10-100 species per year
• background rate should be about 1 every 200 years

Question 19

what is the IUCN Red List?

Answer 19

• it identifies and assesses the conservation status of species
• raises awareness of species which face a higher risk of extinction than others

Question 20

what are some factors that might make a species more prone to extinction? (these same factors are used to determine the Red List)

Answer 20

• population size > smaller population > less genetic diversity > more likely to go extinct eg. cheetahs
• degree of specialisation > more specialised = more at risk > if resource/habitat is threatened, species is too eg. koalas and eucalyptus
• distribution > small area = more at risk
• reproductive potential and behaviour > long-living species usually have low reproduction rate therefore more vulnerable to extinction eg. elephant/rhino
• geographic range and degree of fragmentation > if fragmented or restricted habitat = more at risk > because harder to maintain large population sizes
• quality of habitat > better = less at risk
• trophic level > top predators more sensitive to changes lower down in food chain > 10% rule
• probability of extinction

Question 21

why are tropical biomes at risk?

Answer 21

• demand for timber, beef, soya, oil palm, biofuels
• recovery depends on extent of disturbance
• difficult to regrow tropical biome in thin, nutrient-poor soils

Question 22

outline the conflict between exploitation, sustainable development, and conservation in tropical biomes. how would this conflict be more of a problem as most tropical biomes occur in less economically developed countries (LEDCs)?

Answer 22

• exploitation -> want to generate income regardless of environment
• conservation -> see intrinsic value of biome, rather than ways to make money
• sustainable development -> conflicts w/ both as has to compromise with some exploitation and some conservation
  in LEDCs:
  *reliance on tropical biomes for resources to generate income & make a living
  *aren’t many other industries so exploitation of resources improves economic situation and GDP of country
  *political unrest can mean issues to do with conservation may be overlooked

Question 23

give a case study of a species that has become extinct due to human activity.

Answer 23

Steller’s sea cow:
- large aquatic mammal
- became extinct in late 1760s due to overhunting for skin, meat, and fat
- also sea otter population greatly diminished so overpopulation of sea urchins, which prevented growth of kelp which sea cows fed on

Question 24

give a case study of a species that is critically endangered.

Answer 24

black rhino:
- population declined as result of european hunters and settlers
- also because of wildlife crime -> poaching & black-market trafficking of rhino horn
- to try to improve: donate to WWF OR use & support sustainable wood, paper, and palm oil

Question 25

give a case study of a species whose conservation status has been improved by intervention.

Answer 25

peregrine falcon:
- conservation status least concern in 2021
- 1970s: listed as endangered due to DDT & other pesticide use as they contaminated their diet of other birds and fish
- population started increasing after DDT use was restricted & based in USA (1972)
- conservation work also helped save species from extinction (eg. captive breeding programmes)
- also at risk from loss of habitat, egg collection & trading, and global warming

Question 26

give a case study about the threats to biodiversity from human activity in a natural area of biological significance.

Answer 26

great barrier reef:
- ecological pressures: climate change as warmer weather leads to coral bleaching & increase in severe weather events that destroy coral
- socio-political pressures: coastal development eg. port building/island development
- economic: tourism as boats damage coral AND sediments & pesticides from agricultural/industrial run-off
- consequences of losing biodiversity in great barrier reef: marine food-webs would be altered, decreasing no. fish as food source for people AND shorelines more vulnerable to erosion