Topic 3 Flashcards
(26 cards)
what are the 3 forms/types of biodiversity?
species diversity
habitat diversity
genetic diversity
what is biodiverstiy?
number of species in an area and their relative abundance that can be measured by: species, habitat, and genetic diversity
what is species diversity?
in communities it’s a product of 2 variables: no. species (richness) AND their relative proportions (evenness)
what is habitat diveristy?
refers to a range of different habitats in an ecosystem or biome
what is genetic diversity?
refers to the range of genetic material present in a population of species
how can biodiversity be measured?
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
what could low biodiversity indicate?
- 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
why is it important to measure and quantify biodiversity?
- 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
what are the origins of biodiversity? (ie. how has biodiversity arisen?)
biodiversity arises from evolutionary processes - natural selection
what is evolution?
a gradual change in the genetic character of populations over many generations, achieved largely through process of natural selection
how has biological variation arisen? how can this variation affect an individual?
- 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
what is the process of natural selection?
- 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
what is speciation?
- formation of a new species when populations of a species become isolated and evolve differently from other populations
- occurs over long period of time
how can populations become isolated? (2 ways)
- 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
how has tectonic plate movement/activity influenced evolution and biodiversity?
- 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
what factors have caused mass extinctions in the past?
- tectonic plate movement
- super-volcanic eruptions
- climate changes -> droughts and ice ages
- meteorite impact
how do mass extinctions link to biodiversity?
- 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
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)
- 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
what is the IUCN Red List?
- it identifies and assesses the conservation status of species
- raises awareness of species which face a higher risk of extinction than others
what are some factors that might make a species more prone to extinction? (these same factors are used to determine the Red List)
- 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
why are tropical biomes at risk?
- demand for timber, beef, soya, oil palm, biofuels
- recovery depends on extent of disturbance
- difficult to regrow tropical biome in thin, nutrient-poor soils
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)?
- 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
give a case study of a species that has become extinct due to human activity.
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
give a case study of a species that is critically endangered.
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
