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

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

     

Conservation in Captivity

  • Zoos can also contribute towards the conservation of endangered animal species
  • Captive breeding programmes can breed individuals of a species so their offspring can be released into the wild
  • Zoos are an invaluable resource for scientific research
    • Scientists are able to closely study animal’s genetics, behaviours and habitat needs

     

  • There are some problems with zoos and their role in conservation:
    • Captive breeding of small species populations can reduce genetic diversity
    • Certain animal species will not breed in captivity
    • Not all zoos can provide adequate habitats for animals with specific needs

     

  • There are stories of both success and failure when it comes to zoos and conservation:
    • The oryx is an antelope-like species that was saved from extinction and reintroduced into the wild in Africa thanks to zoos and captive breeding programmes
    • Pandas have been in captive breeding programs for over 60 years and not a single panda has been reintroduced into the wild

     

  • Botanic gardens are the plant equivalent of zoos
  • They use cuttings and seeds collected from the wild to establish a population of the endangered species in captivity
  • Methods of tissue culturing and cloning can also be used to obtain large numbers of plants from a small sample size
  • The captive population can be used in the future for reintroduction into habitats where they have become rare
  • Research is a major role of botanic gardens
    • They investigate reproduction and growth in different plant species so that they can be grown in captivity
    • If the plants original habitat no longer exists they try to find suitable new habitats

     

  • Both zoos and botanic gardens are instrumental to education
    • They help to raise awareness of vulnerable, endangered species and conservation efforts worldwide

     

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

Summary-of-Conservation-of-Endangered-Species-Table

 

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)

     

Worked Example

A biological investigation was conducted to find out if removing invasive signal crayfish would help to conserve native white-clawed crayfish. Every year for six years the number of individuals of native crayfish in a 50m section of a stream was estimated using random sampling. After two years, all the signal crayfish in this section of the stream were removed (with regular removals continuing to be carried out after this time). A 50m section of a very similar stream (in terms of biotic and abiotic conditions), in which the signal crayfish were not removed, was used as a control site. The results are shown below. Describe and draw conclusions from the data, then evaluate the method used to collect the data.Crayfish-experiment-1v

 

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

Worked Example

Another investigation into the effect of invasive crayfish on the numbers of native crayfish was carried out in a 20m section of a stream in a different part of the UK over a period of 18 months. The results are shown below. Describe and draw conclusions from the data, then evaluate the method used to collect the data.Crayfish-experiment-1-1

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

 

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