AQA A Level Biology复习笔记7.4.8 Conservation & Human Need

• Humans use many resources from the Earth such as land (for settlements and agriculture), water, wood and fossil fuels
• As the human population increases and countries become more economically developed, our requirement for these natural resources also increases
• This is having a harmful effect on many aspects of the environment, including aquatic and terrestrial ecosystems, and our atmosphere and climate
• The damage to these ecosystems is negatively impacting the species and habitats contained within them
• This means that a conflict exists between human needs and conservation
  • Conservation is the protection and management of species and habitats (i.e. ecosystems) in a sustainable way
  • Sustainable use of ecosystems (and the resources they provide us with) means using these resources in a way that meets the needs of humans alive now, without reducing the ability of future humans to meet their own needs
  • However, not everyone agrees with conservation and sustainable practices, as this may appear to limit them in certain ways (e.g. financially) in the short-term
  • Careful management of natural resources is required to ensure humans use them sustainably but in a way that still fulfils their current needs

   

An Example of the Conflict Between Human Needs and Conservation

• A well-known example of how the conflict between human needs and the conservation of species has been resolved through careful management can be seen in the Maasai Mara national reserve in Kenya
  • This is an area of savannah (grassland) in Africa that contains a high diversity of species

   

• The Maasai people raise livestock (e.g. cattle) on the land but this can damage the ecosystem through overgrazing of livestock, leaving less grassland available for wild species, and deliberate poisoning of predators that occasionally kill the livestock (e.g. lions, which are an endangered species of conservation concern)
  • This causes a conflict with conservationists

   

• Through working closely with the Maasai people and understanding their needs, conservation trusts are helping them to make money from their land in other ways or from continuing farming done in a more sustainable way. For example:
  • Employing local people to work on conservation and ecotourism projects
  • Employing local people to monitor the lions and their locations (using GPS tracking systems), which allows farmers to move their livestock away from certain areas before the lions arrive, instead of resorting to poison

   

• In these ways, the needs of the Maasai people can be met, whilst also protecting the biodiversity of the savannah

Methods of Conservation

Conserved Areas

• National parks are areas within countries where the wildlife and environment are protected
• Governments control these areas and pass legislation to ensure their protection
• There are several restrictions
  • Humans access is strictly controlled
  • Industrial activities such as agriculture and building are tightly regulated
  • Hunting is limited or completely prohibited

   

• Marine parks are protected areas of water that have been set up for the conservation of endangered marine ecosystems and species
  • They also have restrictions to prevent overfishing and pollution

   

• Public engagement with conservation efforts is important for long term success:
  • National and Marine parks can attract thousands of tourists each year which increases money and awareness for the conservation effort
  • Involving members of the local community in the management of protected areas can provide jobs and increase acceptance of the parks
  • Some of the profits made from parks can be used to improve the health and education standards in the nearby communities to illustrate the benefits of having such areas nearby

   

Storing Genetic Material for Conservation

• If a species becomes extinct in the wild then traditional conservation methods are no longer useful
• New technology has provided ways of storing the genetic material of endangered species so that it is not lost forever
• Frozen zoos store genetic material from animals (eggs, sperm, tissue samples etc) at very low temperatures so that they can be kept for a very long time
  • Ideally, samples are collected from different individuals of the same species to maintain the gene pool
  • The temperature used is roughly -196oC
  • A large amount of genetic material can be stored in a relatively small space
  • In the future genetic materials from extinct animal species could be used to breed and reintroduce a species through IVF and genetic engineering
  • The San Diego Zoo in the USA has frozen zoo facilities

   

• A seed bank is a facility that conserves plant diversity by drying and storing seeds in a temperature-controlled environment
  • Usually, seeds of the same species are collected from different sites to maintain the gene pool
  • If the plant species goes extinct then the seeds can be used to grow them again
  • Seeds can only be stored for so long. After a certain period of time, the stored seeds are grown into plants and fresh seeds for storage are taken from those plants
  • The Svalbard Global Seed Vault in Norway has almost 1 million species of plant seed. It is located in the Arctic Circle with ideal environmental conditions
  • Many organisations send seeds from crop plants to be stored there for safekeeping

   

• Some plants have seeds that can not be frozen such as coffee and cocoa plants
  • In order to preserve the genetic diversity of these plants successive generations must be grown or tissue cultures taken

   

Summary of Conservation Methods

Evaluating Data About Conservation Issues

• Being able to evaluate evidence and data concerning issues relating to the conservation of species and habitats is an important skill
• The example below demonstrates these data evaluation techniques using data on white-clawed crayfish and signal crayfish
  • The signal crayfish is an invasive species in the UK that arrived from America and has since caused major declines in our native species, the white-clawed crayfish, through competition for resources and the transmission of a disease that is fatal to white-clawed crayfish (but not signal crayfish)

   

Step One: Describe the data

• Over the first two years, the number of native crayfish approximately halved, decreasing from 50 to 25. After the invasive species was removed, the number of native crayfish increased from 25 to 45 in 4 years
• The control site showed a decrease in the number of native crayfish, from 60 to 20 over the six-year period

Step Two: Draw conclusions

• The removal of the invasive crayfish led to an increase in the number of native crayfish over a four year period
• This suggests that the decline in white-clawed crayfish populations in the UK could be due to competition with the signal crayfish

Step Three: Evaluate the method

• Due to the control experiment, where the number of native crayfish continued to decrease throughout the six-year study, any other variables that could have affected the number of native crayfish (including abiotic factors such as water quality and biotic factors such as predation) can be discounted. This increases the validity of the results
• As random sampling was used, the data will not be biased and will give a more accurate estimate of the whole area

Considering Conflicting Data About Conservation Issues

• The results (data) from just one study are not normally enough to draw certain enough conclusions on which to base conservation actions
  • For example, although the results of the investigation outlined above seem to suggest that signal crayfish are causing the decline of white-clawed crayfish, it is unlikely that this one study would lead to conservation action to remove signal crayfish all across the UK

   

• Instead, the results from multiple similar studies are normally required and if these results appear to agree, then a more certain conclusion can be drawn
• Sometimes, however, two very similar studies may give different results that do not appear to agree
• Being able to consider this conflicting evidence and its implications is an important skill

Step One: Describe the data

• Over the first six months, the number of native crayfish decreased from 25 to around 13. After the invasive species was removed, the number of native crayfish continued to decrease from 13 to around 9 over the next 12 months

Step Two: Draw conclusions

• The removal of the invasive crayfish had no effect on the declining native crayfish population
• The conflicts with the results of the previous study, which suggested that the decline in white-clawed crayfish populations in the UK could be due to competition with the signal crayfish

Step Three: Evaluate the method

• There was no control site in this investigation, so the continuing decline of the native crayfish after the invasive species was removed could be due to another biotic or abiotic factor, such as the presence of a new predator or a change in the water quality or temperature
• The length of this investigation was much shorter than the previous study, so the decline in native crayfish could simply be due to a natural population fluctuation, meaning that the population may increase again if studied over a longer time period
• The study area was much smaller than in the previous study, so the estimated population size values may be less accurate