OCR AS Biology Unit 2 Module 3 Extinction + Conservation

Editor's Notes

• #4 Iris: Extinction is when a species ceases to exist.
• #5 C-J: There can be several reasons as to why an animal doesn’t exist anymore  Iris: Extinction can happen suddenly or it may take millions and millions of years.  C-J: Genes can affect extinction as well. We all know that natural selection happens. But if you have a small population and a narrow gene pool, other animals which are better adapted to that changed environment can get rid of those animals. (Natural Selection)  Iris: Things that we- as humans do- such as overharvesting, pollution, habitat destruction, new predators, over hunting, etc.  C-J: When you have a rare organism that can be bred with a more common organism (this is called hybridization), this can cause extinction to the rarer organism.  Iris: When an animal’s habitat is destroyed (Habitat Degradation) so much that they can’t survive. As an example a rainforest with a fern that depends on dense shade for protection from direct sunlight can no longer survive without forest to shelter it. Global Warming is also a part of this as some animals that lived in very hot countries like the Arizona desert can venture out further, bringing out more competition to the other animals that were initially living in that other space. Water and food can have limits during habitat degradation which lead to extinction.  C-J: Introducing ‘alien’ organisms to a native organisms not only brings on more competition but the foreign organisms can carry viruses and bacteria that the native organism isn’t used to, and by accident kill that whole species off. – Lucayan Iris: You can also have scenarios where when one species if extinct another one connected to it can die as well. For example; if all flying insects were swatted to death, flowering plants could become extinct because none would be able to pollinate them.  C-J: Extinctions can also happen from natural phenomena, like storms, or even meteorites.
• #6 Iris: But not all extinction is bad. Smallpox is almost extinct in the wild, and polio is only contracted in very small parts of the world. There is also suggestions of a planned extinction of mosquitoes that carry the malaria virus (Anopheles), dengue fever, yellow fever, and elephantiasis (Aedes)
• #7 Iris: When a species becomes extinct the niche it lives in has biodiversity. Biodiversity is the variation of life within a certain ecosystem.  C-J: Biodiversity matters because it affects not only animals but humans as they need a steady stream of food, raw materials, and medicine. But regardless of that, biodiversity is dropping. Many animal and plant populations are declining in numbers and/or areas.  Iris: when we were in Wakehurst Place, the lady doing the presentation had mentioned some ways that humans are causing a loss of biodiversity such as:  C-J: Increase in human population – increased use of land for homes and growing food crops, Deforestation, Global warming, Extinction of species – with useful genes for foods and medicines, Damage to natural ecosystem – such as soil erosion  Iris: these activities are all causing a loss of biodiversity which in turn is causing a decrease in the gene pool.  C-J: So to stop this we must… get more protected areas such national parks and educate people about loss of biodiversity and there affect on the world.
• #9 C-J: we’ve grouped the reasons to conserve in 4 categories: economical and ecological; ethical and aesthetic; agricultural, and medical reasons which we’ll explore them one by one.  Iris: and we’ll give you some tips on how to conserve at the end
• #10 Iris: So why do we conserve biodiversity, C-J? C-J: Well, Biodiversity is a fundamental part of the Earth’s life support system. It supports all basic natural services for humans, such as fresh water, fertile soil and clean air. As mentioned before many harmful human activities are all causing a loss of biodiversity which in turn is causing a decrease in the gene pool.  Iris: Biodiversity plays a role in regulating natural processes such as the growth cycles of plants, the mating seasons of animals. It helps pollinate our flowers and crops, recycle our waste and give us our daily bread. So basically, without biodiversity, we won’t be able to survive.  C-J: The term biodiversity also reminds us that no one organism lives in isolation. The many different ways that the millions of organisms on the Earth interact with each other contributes to the balance of the global ecosystem and the survival of the planet.  Iris: Conserving biodiversity is about genetic variety, species, habitats and ecosystems. All are important, but it is often most sensible, practical and effective to conserve species. Now here are some more specific reasons for conserving species: (next slide)
• #11 C-J: Species, by their very nature, have specific ecological requirements. They may appear to share the same habitat with many others but each has a different, specific niche. It is what sets them apart, and makes them what they are. Iris: Keystone species play significant roles in regulation of ecosystems - balancing the ecosystem. A keystone species is a species that has a disproportionate effect on its environmentrelative to its abundance. Such species affect many other organisms in an ecosystem and help to determine the types and numbers of various others species in a community. C-J: for example, some sea stars may perform this function by preying on sea urchins, mussels, and other shellfish that have no other natural predators. If the sea star is removed from the ecosystem, the mussel population explodes, driving out most other species.  Iris: In the African savanna, the larger herbivores, especially the elephants, shape their environment. The elephants destroy trees, making room for the grass species. Without these animals, much of the savanna would turn into woodland. C-J: Evolution has provided answers to many technological problems we face. For example, the concept of making an aeroplane flies was based on the principle of birds flying.  Iris: If we allow species to go extinct, we could be losing many solutions to new problems C-J: Without nutrients and disposal of waste soil will become infertile, some modern farming methods are also creating problems since people do not allow soil to regain its fertility after one harvest before planting the second. Without fertile soil we will not be able to grow enough food which will create food shortages and a raise of food prices
• #12 C-J: Some species have obvious public appeal. People can identify and relate to a lapwing much more easily than to coastal floodplain grazing marsh. Iris: Loss of habitat and biodiversity prevents many organisms from living where they should e.g. human groups still living in natural habitats  C-J: many people also enjoy observing wildlife and natural landscape such as chalk downland and heathland Iris: Natural systems are very important for our wellbeing + for our physical, intellectual and emotional health
• #13 C-J: maintaining biodiversity for agriculture is important because we need to retain a huge reserve of gene information for use in future  Iris: for example, the genes of the 3 great staple food – wheat, maize and rice should not be destroyed or it will lead to starvation. C-J: It is estimated that locally adapted breeds of animals are lost worldwide at rate of 1 / week since modern crop plants are being produced by selective breeding nowadays Iris: Climate changes – some areas too hot and dry to support agriculture – so scientists look at the variation that already exists within crops and their wild relatives to breed new varieties C-J: Spreading of diseases – not only humans are being affected  crop plants at risk e.g. new strain of a fungal pathogen of wheat, black stem rust, has spread throughout East Africa – wheat plants have no resistance to this strain causing loss in yield  disease could spread further with global warming
• #14 Iris: for many years medicinal effect had been identified in many plants since they have complex metabolisms that produce a wide range of chemicals which might be of use to humans C-J: for example, vinblastine, which was originally extracted from plants is an anti-mitoticdrug used to treat certain kinds of cancer, including Hodgkin's lymphoma, non-small cell lung cancer, breast cancer, head and neck cancer, and testicular cancer. Iris: TAXOL, or Paclitaxel is a mitotic inhibitor used in cancerchemotherapy. Paclitaxelis now used to treat patients with lung, ovarian, breast cancer, head and neck cancer.  C-J: Herbalism, a traditional medicinal or folk medicine practice based on the use of plants and plant extracts is also very useful as shown in the use of traditional Chinese medicine  Iris: for example, Pei Pa Koa – is a kind of medicine which uses Mentholum, Poriaand all kinds of herbs to relief cough, sooth sore throat and remove phlegm C-J: There may be potential drugs in plants that have yet to be identified So it is important to maintain plant, animal, and microorganism diversity.
• #15 Lastly,here are some ways you can help conserving species. That’s the end of our Presentation, thanks. 