Biodiversity Peter Shaw USR
Why me? • A keen personal interest in conservation issues since early years (initially birdwatching). • Some active involvement in conservation volunteer work. • organised a 2 year programme of badger watches. • have undertaken research on the conservation management of industrial sites. • have published articles on the subject, with a strong bias towards post-industrial landscapes.
Introduction • This is the start of my module about biological conservation. I should start by explaining the scope of the module: • This is my personal selection of conservation issues - I do not pretend it to be the definitive collection: life is too short! • The pattern of lectures: • 2 generic • 5 on UK issues • 5 on global issues
Conservation and Biodiversity • Aim of today • To introduce you to the basic ideas behind conservation biology • To attempt to explain the term “biodiversity”. • To suggest to you that we are living in the middle of an extinction event.
2 really basic concepts: • I’ll use these words a lot in this module – best to check you’re happy with them: • Species, Endemic • Species • Exam answer: “A species is when 2 things are completely different, like the French are one species and the Germans another” • Actually the notion of a species is a blurred one. It implies a genetically closed population, so that organisms from the same species can cross-fertilise. In practice it is almost always based on gross morphology – does 1 extra hair on an insect’s leg define a new species? (Yes, if it is a constant trait in the population)
Endemic • An endemic species is one confined to a small geographical area. The correct terminology is to that the species is endemic to an area – thus the dodo was endemic to Mauritius. • Remote oceanic islands are often hotspots for endemism. Mountain tops can act as islands in the same way, and mountain ranges often support endemic species. (The pyrenean desmin – a sort of giant swimming shrew, a very primitive mammal – is endemic to the Pyrenees.)
Why focus on the UK? • Not for our species richness. In terms of global biodiversity, the UK is trivial. We have 1 endemic bird species, a few endemic sub-species of bird and mice, a handful of endemic plants. • For two reasons: • The natural history of the UK better known than any other country in the world, thanks to a legacy of victorian naturalists. We invented the study of natural history! • 2 We live here, and you may become involved in UK conservation work. Think globally, act locally.
UK Endemics • We have 1 bird species: the Scottish crossbill Loxia curvirostra. This finch only lives in the ancient Caledonian pine forests in central Scotland, and represents an isolated population that separated off from Continental crossbills some 10,000 years ago. • (It shares this habitat with an isolated population of crested tits Parus cristatus, and I suspect that when the DNA people look at these they’ll find that these tits are as genetically disjunct from the mainland forms as are the crossbills).
Subspecies: • The red grouse is endemic to the British Isles, but is a subspecies of the mainland willow grouse. • We have endemic subspecies of rodents: the St Kilda vole, the Skomer vole – on our offshore islands.
Endemic UK plants • There are some species in the whitebeam/rowan genus Sorbus which are confined to remote limestone outcrops in the UK. • A new orchid Young’s Helleborine Epipactis youngii appeared on coal spoil bings near Glasgow in the 1980s.
What is meant by conservation? • Conserve wildlife! Pickle a squirrel (/traffic warden…) • “Conservation“ in the sense of this module has changed subtly from its the original sense of preserving in the sense of stuffing / freezing / pickling material. • “Conservation”, in the sense of this module, means preserving the existence of life-forms. This is a dynamic exercise, and may involve destructive actions (clearing plants, killing competing animals) if there is a sound ecological reason for doing so.
Are you sure it’s conservation? • Heathland managers burn their ecosystem and chop trees down • Round Island was cleared of rabbits using about hundreds of kilos of warfarin. • In these cases, plus many more, these violent interventions are needed to maintain a balance.
Ethics (or lack of) • Actually I want to minimise ethical analyses. I now know myself to follow a school of ethics known as the teleological. The test that matters to me is “What are the outcomes of decision, and how do I weigh them up?” • There is an alternative school (known as deontological) who attach weigh to certain absolute imperatives “You must not kill animals” “Animals are best left in the wild”. • Tigers look sad pacing up and down in cages. As the numbers of tigers in Bali declined in the 1950s and 60s, some people objected to plans at capturing the last wild animals for zoos. The sub-species is now extinct. I think that to be a worse outcome than having Bali tigers pacing up and down. • (Condors too – more later)
The big test to apply: • The correct question to ask in a conservation setting is “What management maximises global biodiversity?” • If the alternative to grouse shooting is forestry (which it is), and the endemic red grouse cannot survive in forests (which it can’t), grouse shooting is a rational conservation solution.
RIL: Guardian Friday January 28, 2000 The new millennium has started woefully for Capra pyrenaica pyrenaica, a species of Pyrenean mountain goat. Despite money from Europe, new international laws, regional aid and the best efforts of conservationists, the last of a long-horned, short-haired line stretching back into antiquity died on January 6 after a tree fell on it. It is a snaphot of what may happen in the next few decades to at least 10 more European species. The World Wide Fund for Nature yesterday declared that the Iberian lynx, brown bear, harbour porpoise, monk seal, loggerhead sea turtle, a freshwater mussel, Atlantic salmon, marsh fritillary butterfly, lady's slipper orchid and corncrake are in serious decline in EU countries. Falling trees aside, the constant erosion of animal and plant habitats is blamed for the decline of these and other European species. The WWF says this is the last chance to save them. Several species found in the UK are under severe pressure. The corncrake and marsh fritillary have been the victims of intensive agriculture as ploughing and pesticides destroy habitat and insects. The harbour porpoise is vulnerable to drowning in fishing nets. Research suggests there are fewer than 650 Iberian lynx left in the wild. Monk seal numbers are put at 500. The WWF is calling on the British and other governments to implement the EU habitats and species directive, which would give further protection to endangered species. Stuart White of the WWF said yesterday: "European governments have had an excellent conservation law available to them since 1992 to prevent these declines. But they have failed to meet every deadline for putting the law into practice." The directive was supposed to become national law in all EU countries in 1994 but is not fully on the statute book in any country. Sites for protection under it were to be proposed by the countries by June 5, 1995. All failed to meet that deadline and have been asked by the European commission to propose more sites. As a result not one country has met the directive's requirements. The commission has started legal action against Britain for its failure to designate enough sites. And the big problem: • The planet has a BIG problem. We are losing species. • How many species? Even the answer to that is unclear. We have c. 1.4 million species preserved in museums, but think there to be 20-30 million species alive. • This figure is argued over, and clearly depends on how tightly you define species. However you draw species boundaries, the total alive now is less than it was 20 years ago, and is certain to keep declining. (Europe lost a species 6 January 2000 – a wild pyrenean goat Capra pyrenaica pyrenaica. A tree fell on the last survivor).
2 Qualifications: • 1: Species are capable of forming. Epipactis youngii was named from plants on coal bings in the 1980s. (But was then renamed as an unimportant hybrid in the 1990s…). A new species of Amanita (mushroom) appeared in Surrey 1981 – but is probably wild in the Antipodes somewhere. Wallabies escaped in Hawaii have changed size habits and colour so dramatically in 80 years that they would certainly be called new species if found in nature. So it can happen - It’s just that this is a very very rare event. • 2: New species are waiting to be discovered. 2 new large mammals (a goat and a deer) were found in Vietnam in 1990s. One of the turned out to be genuine (the other an embarrassing fake make from a cows horn!) Sonic surveys of bats and bushbabies have turned up new species under our noses – the commonest UK bat turned out in the 1990s to be at least 2 species..
Extinction is natural • Almost all species go extinct eventually. We have one species known to be unchanged for over 400 million years – a lamp shell called Lingula. • A few extinctions are semantic rather than real: Homo erectus is gone, but the line did not go extinct. Homo erectus 500,000 years ago Homo sapiens present day
Background extinction rate • At a purely pragmatic level, proving a species to be extinct is very difficult. It’s not too bad finding elephants – mammoths are unlikely to remain undiscovered in Siberia – they are just too big to be overlooked. Birds and small mammals are harder to find, and for insects the simple failure to rediscover is no proof of extinction. (A friend rediscovered a beetle for the 1st time in 100 years in the UK recently, in precisely the same spot where a Victorian had found it). • From fossil evidence we have a rough figure that one species goes extinct per million years. At a few points in the geological record, extinction rates increase hugely, marking the end of one geological period and the start of another. These are Mass Extinction Events.
Mass Extinctions.. • The biggest was at the end of the Permian, when 99% of all species went extinct in one geological event. We do not yet know why, but there is evidence that the atmosphere became depleted in oxygen. • The best known one was 65mybp, the C/T boundary event which marked the end of the dinosaurs (and pterosaurs, plesiosaurs, ammonites…). • For years books explained this as racial senility, volcanic activity, change of vegetation, rise of mammals… all rubbish. There is excellent evidence that the event was an impact by a large meteor. • This body was c. 10km diameter, falling at c.15 km per second. The impact zone was land now by the Yucatan peninsula, Mexico. The impact energy vapourised most of North America, and blacked out the sky over the whole planet for several years. • How do we know it won’t happen again? Actually it could happen, pretty well at any moment. Astronomers think that they have tabs on all the big objects likely to impact on us, but a 1m boulder could just appear and release a Hiroshima anywhere, any time. We get several per century.
Actually our ancestors started one too.. • The most recent mass extinction started c. 10,000 BP – the Pleistocene extinction event. • This was odd – all other MEEs removed small animals as well as large –the Pleistocene event was a selective removal of large species. • Mammoth, giant elk, sabre-toothed tigers, dire-wolves… The threshold for removal is said to be 60Kg, but don’t worry about this figure too much. • Old books say the European megafauna went extinct because the climate warmed up too much – in fact there had been several previous interglacials, and mammoths etc had flourished. This extinction was our ancestors.
Mammoth soup • I would prefer not to tackle a mammoth with a spear – but there is excellent evidence that hunting by our ancestors drove them to extinction. • In the Ukraine a 15000 year old village has been excavated, where all the buildings were mammoth bone, probably covered in mammoth hide. • The area also held deer, horses, bison, musk ox; only deer remain.
The same story.. • Wherever humans appear, giant animals vanish. Mammoth in Asia, giant marsupials in Australia, giant lemurs in Madagascar, giant ground sloths in South America, giant Moas in New Zealand. • (Interestingly, the stronghold for surviving large fauna is in Africa, where humans evolved. Perhaps they learned to fear humans before humans became too effective at hunting?)
and the non-target species • Removing megafauna took out non-target species. New Zealand had a giant eagle adapted to eating Moas – when the Moas became extinct,so did the eagle. Condors were scavengers of megafauna – they are still with us, but only just.
The Golden age that never was • Please don’t let anyone ever tell you that our ancestors had a harmony with the world that we lack. They exterminated more large mammals than we have managed (and probably invented genocide too – ask the Neanderthals). The species we have left are the “tough” ones to remove – the easy ones went long ago.
Red data books • Despite all its tribulations, we still have a good diversity of life on the planet. The IUCN lists those species which are still alive, but considered in some danger. These lists are known as red data books. • In 1990 it listed 698 mammals, 1047 birds, 191 reptiles, 63 amphibians, 762 fishes and 2250 invertebrates. A separate RDB for UK insects alone lists 1800 giving cause for concern. • Actually this only scratches the surface of the problem.
Extinctions we know about • From ad 1600‑ad 1900 man is known to have exterminated c. 75 spp. (1 per 4 years) • Since 1900 we know that there have been c. 1 sp / yr, and this is still true today for described species. • Our modern rate may be 100 sp per year, or per day- it all depends on which models you believe (more later..)
Biodiversity • ..Is what we’re left with after all these extinction processes. It’s what this module is all about. • It has 3 facets: • Habitat (ecosystem) diversity • Species diversity • Genetic diversity
These 3 are inter-twined • To preserve the genetic diversity in a species you need to maintain population size, and to do this you need to preserve it’s selected habitat. Often a key point in conservation management is to maintain the diversity of habitats: this maximises the diversity of species.
Patterns in biodiversity: • The clearest pattern is with respect to size. There are many more species of small organisms than of large ones. Roughly 10* smaller = 10* more species. • The distribution of species numbers is very irregular between life forms – mammals are one of the most minor of groups!
Beetles • JBS Haldane was once asked what zoology revealed about the mind of God. • “An inordinate fondness for beetles” he replied. Beetles are the most species-rich group on the planet (though bacteria could probably beat them if we could only isolate them all).
Tropics • Another main pattern in the distribution of life is a pole-tropical gradient. Oddly, no-one can really explain this – or rather, lots of people can but they don’t agree on why. Whatever the reason, there are vastly more species of almost everything in tropical areas than cooler ones. (Mayflies and salamanders don’t follow this rule). • Hence the greatest pool of species diversity on the planet is tropical beetles.
19 trees of in Panama Luehea seemannii had 682 herbivores, 296 predators, 69 fungivores 96 scavangers. % host specific is unknown but guessed at 20% for herbivores (probably conservative) and < for other groups; a few more assumptions give you 30E6 spp. in total Mind-numbing figures. • Work in the 1990s fogged insects out of 19 individuals of 1 tree species in Panama. They found 682 species of herbivores, 296 of predators, 69 of fungivores and 96 scavengers. • A few assumptions give you an estimate of 30 million spp. in total – just insects, in tropical trees.
But aren’t they being cut down? • Tropical forests are being logged worldwide, making it awfully likely that we are losing species that we don’t know about. “Centinal” species is the name for these ghostly entities, and they come (or rather, go) in huge numbers. Maybe 100 per day, if you believe the models and the extrapolations. • Do they matter? Have we as a species any right to remove other species thus? Or do we as western educated individuals have any business criticising third-world loggers who earn a pittance? Or their countries who have so few resources to utilise? You must decide these matters for yourselves.