Transcript Biodiversity - Demon Internet

Biodiversity
Peter Shaw
USR
Why me?
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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
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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
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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:
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I’ll use these words a lot in this module –
best to check you’re happy with them:
Species, Endemic
Species
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Exam answer: “A species is when 2 things are completely
different, like the French are one species and the Germans
another”
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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
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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?
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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.
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UK Endemics
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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:
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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
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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?
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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?
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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)
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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:
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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:
And the big problem:
Guardian
Friday
 The planet has a BIG problem. We are losing
January 28,
species.
2000
How many species? Even the answer to that is
unclear. We have c. 1.4 million species preserved in
The new
museums, but think there to be 20-30 million species
millennium
alive.
has started
woefully
forfigure is argued over, and clearly depends on
 This
Caprahow tightly you define species. However you draw
pyrenaica
species boundaries, the total alive now is less than it
pyrenaica,
was a20 years ago, and is certain to keep declining.
species
of
(Europe
lost a species 6 January 2000 – a wild
Pyrenean
pyrenean goat Capra pyrenaica pyrenaica. A tree fell
mountain
on the last survivor).
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goat. Despite
money from
2 Qualifications:
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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
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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
500,000 years ago
Homo sapiens
present day
Homo erectus
is gone, but the
line did not go
extinct.
Background extinction rate
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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..
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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..
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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
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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..
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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
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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
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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
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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
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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
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..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
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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:
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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
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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
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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.
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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?
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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.