A4.2 Conservation of biodiversity (CTs) Flashcards
(16 cards)
Biodiversity and how it is quantified at different levels
Biodiversity: variety/ multiformity of life
Exist at multiple levels:
1. ecosystem diversity
- variety in the combinations of species living tgt in communities
- diversity is partly due to the very varied environments on Earth
- also partly due to the geographical ranges of organisms
2. species diversity
- the many diff species on the evolutionary tree of life
- these species have varied body plans, internal structure, life cycles, modes of nutrition
3. genetic diversity within species
- variety in the gene pool of each species
- variation between both geographically separated populations & within populations
- species with only a few surviving Indivs inevitably have little genetic diversity & problems due to inbreeding
Compare the number of species on earth today with past levels of biodiversity
- less than 2 million species have been named and described & many more remain undiscovered –> estimates between 2-10 million
- with prokaryotes there are too many uncertainties for reliable estimates of numbers of species to be made
- even more diff to estimate how many eukaryotic species on earth in the past
- relative levels of biodiversity can be deduced from fossil evidence –> large variations
Mass extinction
5 mass extinctions & most recent was 66 million years ago at end of cretaceous period
- huge asteroid collided with earth –> environmental disruption caused many species to die out )non-avian dinosaurs)
- previous 4 mass extinctions due to volcanic acitivyt and major changes to atmosphere and global climate
Between mass extinction events, biodiversity tends to rise gradually, with new forms of life evolving. eg extinction of non-avian Dinos and other groups at the end of the cretaceous was followed by evolution of many new species of birds and mammals
Anthropogenic causes of species extinction
*Species extinction is balanced by evolution of new species –> biodiversity don’t decrease
- Overharvesting
- humans take plants & animals from ecosystem by hunting, harvesting for food/ medicines, logging forests to obtain timber, fishing in freshwater or marine ecosystems
- if this happens at faster rate than species can reproduce, extinction occurs - Habitat destruction
- natural habitats like forests or grasslands destroyed so that land can be used for agriculture & to establish towns and cities–> loss of some species - Invasive species
- alien species when introduced to ecosystems can drive native species to extinction by predation, spreading of pests and diseases, or competition for resources
- endemic species can also become extinct if they hybridise with aliens - Pollution
- chemical industries produce vast range of substances used and discarded into environment
- burning of fossil fuels, agriculture, mining, oil extraction, pharmaceuticals - global climate change
- plants & animals adapt to the conditions they experience
- if conditions change gradually, they will evolve to survive but human activities are causing v rapid changes in temp, rainfall, snow cover
- some can adapt/ migrate but others face extinction
Example of loss of terrestrial megafauna
Giant moas
- a group of flightless birds, native only to New Zealand
- there were 9 species, the largest of which were the giant moas on the North and South island
- grew up to 3.6m tall and 230kg
- New Zealand was not settled by humans until arrival of Polynesians in 13th century who became the Maori iwi –> took less than 200 years for all species of moa to be hunted to extinction
Loss of marine species
Caribbean monk seals
- declared extinct in 2008
- docile marine mammals living in and around waters of Gulf of Mexico and Caribbean islands
- prior to European colonisation around carribean area, this seal species was thought to have existed in 13 major colonies, with overall population a quarter of a million
- european colonist killed this seal for oil to use in lamps & food
- the seals often hauled themselves out of water on beaches and rocks and showed little fear of approaching humans –> easy targets for humans with guns and clubs
- some of the last monk seals were killed to provide scientific specimens
Extinction of local species
Atitlán grebe
- this large grebe was endemic in Guatemala at an altitude of 1700m
- small wings and flightless
- its decline began in 1958 where two species of black bass were introduced to the lake to try to promote tourism by anglers
- the fish multiplied and competed for the crabs and fish which were food for grebes & they also predated grebe chicks
- in 1966, a refuge was established for the grebes and numbers rose
- but in 1976, an earthquake fractured the lake bed and water level fell –> only 32 grebes left in 1983
Loss of mixed dipterocarp forest in Southeast Asia (ecosystem loss)
dipterocarpacae is a family of about 700 tropical trees –> MDF has an extremely high diversity of tree species
mixed dipterocarp forest (MDF) typically has high quantities of merchantable timber per hectare
- widely targeted for logging (legal & illegal) –> since 1970s most areas have been lost
- areas which suffer greatest loss are on lowland sites where nutrient-rich soils overlie deep peat –> converted to oil palm plantations which is unfortunate as the peat in these areas can be up to 15m
- drainage during land conversion can cause peat to decompose –> release co2
- rising sea levels due to global warming will flood deep-peat lowland areas –> destroy what little MDF remains
List direct and indirect anthropogenic causes of ecosystem loss
- land-use change for agricultural expansion
- urbanisation causes land-use change
- overexploitation of natural resources (harvesting of keystone species can threaten ecosystem)
- mining and smelting destroy areas of natural ecosystems through land-use change & pollution from these activies can cause widespread damage
- building of dams and extraction of water for irrigation leads to loss of natural river and lake ecosystems
- drainage or diversion of water for human uses has caused loss of swamps and other wetlands in many parts of the world
- leaching of fertilisers into rivers and lakes causes eutrophication and algal blooms (ogliotrophic ecosystems where organisms are adapted to low nutrient concentrations have been lost)
- climate change makes specific patterns of temp, rainfall become variable
loss of Aral Sea (ecosystem loss)
Aral Sea is between Kazakhstan and Uzbekistan is the fourth largest lake in the world
- fed by rivers and no outflows
- lost water by evaporation –> higher salinity than freshwater lake
- in 1960s, the two major rivers that fed it were diverted to irrigate an area of desert –> falling water levels and much of the former lake is desert
- increase in water salinity was major contributor to ecosystem collapse apart from reduction in area and depth of lake –> 24 species of fish were endemic to aral sea and now are extinct & most invertebrate species also disappeared
List the the of evidence that can be monitored to assess the status of a biodiversity crisis
- evidence can be drawn from intergovernmental science-policy platform on biodiversity and ecosystem services (IPBES) reports
- results from reliable surveys of biodiversity in a wide range of habitats around the world
Explain the use of species richness and evenness measures in tracking of biodiversity over time
richness and evenness of biodiversity in an ecosystem are two statistical measures of diversity
- can be gathered through monitoring/ surveys
State the role of “citizen scientists” in monitoring a biodiversity crisis
altho expert scientists plays a key role in monitoring biodiversity and identifying most serious threats, there are opportunities for citizens to contribute
- soem of the the most useful data has been collected by indies who have monitored a popln/ ecosystem regularly over many Years –> allows detection of harmful changes while there is still time for them to be reversed
Discuss the impact of human population growth on the causes of the current biodiversity crisis
- hunting and other forms of overexploitation
- urbanisation with towns and cities growing larger
- deforestation and clearance of land for agriculture and consequent loss of natural habitat
- pollution of land and sea throughout world
- spread of pests, diseases and invasive alien species due to global transport to compete with native species
intensity of these causes has increased significantly due to enormous rise in number of people on earth –> overpopulation is overaching issue that makes human activities a threat to most other species and risks widespread ecosystem collapse
Compare in situ to ex situ approaches to conservation
No single approach itself is sufficient as diff species require diff measures
In situ conservation of species in natural habitats
- ideal approach is to leave areas of earth’s surface in state of pristine wilderness
- partially degraded pristine areas may be extremely valuable for purpose of nature conservation
- legislation/ land purchase can be used to create national parks or nature reserves
- management of nature reserves, rewinding, reclamation of degraded ecosystems
Advantages:
- ensures species live sin abiotic environment to which it is adapted
- allows species to interact with other wild species –> conserve more aspects of organism’s niche and integrity of ecosystem
- animal patterns can remain normal
- costs are low if wildlife reserve is in goof enough state for human intervention to be unnecessary
Disadvantage:
- requires active management like removal of alien species, reintroduction of species that have been locally extinct, decrease/ increase in population sizes of herbivores and predators, prevention of poaching, supplementary feeding, control of access
Ex situ conservation is preservation of species outside natural habitats
- animals removed from wild into zoos, plants grown in Botanic Gardens –> where they propagate plants and breed animals
- zoos must carefully plan captive breeding programmes, followed by release of captive-bred Indisvs back into natural habitats
- in some cases, it is justifiable bc they cannot remain safely in natural habitats so if threat is eliminated, they can be returned to original site
- more radical approach to long-term storage of germ plasma in seeds/ tissue banks to be used for propagation in future –> called germ plasm
Outline the rationale used for conservation by the EDGE of Existence programme
it is the selection of evolutionally distinct and globally endangered species for conservation prioritisation
Uses 2 criteria
1. does the species have few or no close relatives so it is a member of a very small clade?
2. is the species in danger of extinction because all of its remaining populations are threatened?
EDGE= evolutionarily distinct and globally endangered
The species on these lists can then be targeted for more intense conservation efforts than other species that are not threatened/ no close relatives
