What makes some species prone to extinction. A list drawn up by Cox (1997) stated 6 reasons that a species may be more susceptible. Firstly if a species has a low reproductive rate which often coincides with them being a large species. If a species is of high economic value, is at the end of a long food chain, restricted to local insular habitats, is specialised for habitats, breeding sites or food and lastly migratory species.
The question of when a species is endangered is a tricky one to answer and is a matter of discussion. Criteria have been drawn up by the organisations that need to classify the extinction risk of species.
The International Union for the Conservation of Nature and Natural Resources (IUCN) estimates that the extinction rate is between 1,000 and 10,000 times higher than it should be. To estimate the extinction risks red lists are drawn up that categorise species depending on how at risk they are. They have 9 categories and the criteria that a species must fall into is very long and convoluted and I wont go into it here but it can be found in the document, IUCN red data list, Categories and Criteria, version 3.1 February 2000. So far red lists have been produced for the birds and amphibians of the world along with indices that chart the movements of species between the groups.
The convention on international trade in endangered species of wild fauna and flora is an agreement between 169 countries to stop the international trade in certain animals and plants where this trade is threatening their survival. As with the IUCN lists the categories have long and convoluted criteria that I have attached for you to have a look at but in general, they have three groups called appendices. Appendix one contains species that are threatened with extinction and trade is only permitted in exceptional circumstances. Appendix II is for species that are not exactly threatened with extinction but need their trade to be controlled to prevent them from becoming threatened. Appendix III is for species that are protected in at least one country and that country has requested that trade be controlled.
Is it our duty to conserve? This is a personal question and there is no right or wrong answer. Society today generally has a pragmatic-utilitarian set of ethics that believes that human success is important and that technology will solve any future problems we encounter when resources run low. It sees humans and a select few other animals such as pet dogs and whales of primary importance and sees everything else of secondary importance. At the other end of the ethical scale is the ecocentric approach where human and non-humans are treated on the same scale where the lowest right is to existence and the highest is some kind of satisfaction or pleasure. Another question that we must all ask is, is it our duty to preserve things for future generations.
The conservation of plants and animals cost a lot of money. In America the fish and wildlife service has spent huge amounts on the conservation, protection and recovery of some species, for example, the northern spotted owl has cost $9.7 million dollars, the grizzly bear $5.9 million dollars and the Florida panther, $4.1 million dollars. In the UK if every species listed on schedules 5 and 8 had a recovery plan implemented it would cost 800,000 pounds every year for 15 years. Perhaps this money would be better used feeding people and providing housing.
Now comes the next question, when we have decided that we must conserve, what must we conserve? It is not possible to conserve everything. Here are some of the questions that are being asked at the moment and in the next few slides I am going to discuss the merits and down sides to each of these. Firstly, do we conserve single large species and in turn the areas kept for these species will conserve habitat for other species? Do we concentrate efforts on genetically distinct species like the Tuatara or do we conserve 'hotspots' of biodiversity or endemism? Or is the answer to allow species to become extinct as it is 'natural' and focus our efforts on the species that can adapt to human pressures?
Conserving a single large species will in theory conserve large amounts of land that may benefit other species. On the downside, animals like elephants may live in species poor areas where there is little else to conserve. However, the benefits of this are that the public are more likely to give money to a 'save the elephant fund' than a 'save the weevil fund'
Is it important to keep the genes of genetically distinct species? Animals such as the Tuatara are from a very ancient lineage and are the last extant example, is it important to keep these animals or does it not matter as they are only following the trend of their ancestors. The Tuatara was discovered and was clumped with the lizard group although it was noted that it had an unusual skull. It has now been put in the group Rhynchocephalia which is a group equal to the Squamata which contains the lizards and reptiles. The group contains many extinct taxa and there are only two remaining species alive today. These species were once widespread across the islands of New Zealand but are now only found on a few small islands off the coast of the large New Zealand islands. This decline has been attributed to mammal introduction on the islands. Since settlement, pigs, cats and rats are now widespread. Is it important to focus conservation efforts on unique species like this? Or are these animals on their way out anyway.
Is it better to focus upon the land rather than single species? Can we identify hotspots of land where the species numbers are particularly high or is it not that simple? One set of thinking suggests that it is possible to conserve 'hotspots' of land. Land that is rich in species, or has a high endemicity or where high numbers of rare species will be conserved. (Image from news.bbc.co.uk/1/hi/sci/tech/3707888.stm)
In the scientific literature there is argument for and against the conservation of biodiversity 'hotspots'. Some suggest that areas with a large species diversity will most probably have a complex habitat which will in turn allow the conservation of large numbers of other species. Lombard (1995) wrote a paper supporting the use of biodiversity hotspots stating that areas of conservation important to one taxon will be important areas to the conservation of other taxa.
There are as many arguments against the use of hotspots in conservation. One paper by Ceballos et al. (1998) states that there is a low correlation between high species richness and high endemicity. It has also been suggested that hotspots for different species do not often overlap, for example, species richness hotspots for vertebrates and invertebrates are not the same and hotspots may miss a particular species that is important to conservation. Examples of species that are endemic to an area but not in a species rich area are the pocket gopher and the Perote ground squirrel.
As has already been mentioned species are going extinct at a rate 1000 to 10,000 times higher than they should be. Some still argue that extinction is a natural process and should be allowed to carry on. Darwin saw extinction as a process of natural selection. It has even been suggested that the extinctions that humans cause are natural as humans are part of nature! Or are we above nature and it is therefore ours to do what we want with. It all depends how we view ourselves in nature. Maybe we should look to the species that are adapting to our way of life, such as the squirrels and the foxes of the world.
This is a very difficult topic to come to any firm conclusions on. Firstly we have to decide whether it is worth conserving anything and then we have to decide what to conserve and lastly we have to find a way of conserving it.
Cox, G. W. (1997) Conservation biology. Pp 287-296
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CITES. What is CITES [cited 2006 Jul 10] Available from: www.CITES.org/eng/disc/what.shtml
Spellerberg, I. F. (1996)Conserving biological diversity. In Conservation Biology. Pp 25-31
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