Zoos and conservation

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Transcript Zoos and conservation

Zoos, genetics
and conservation
Peter Shaw
I know of two books about zoos which
draw an analogy with Noah’s ark:
The overloaded ark (Gerald Durrell)
Lifeboats to Ararat (Sheldon Campbell)
The aim of today’s lecture is to explore
the extent to which this is possible,
discover Noah’s genetic limitations, and
ask whether there will be a mount Ararat
to land on.
Zoos– a potted history
Oldest animal collection known was at
Saqqarah, Egypt, 4500 BP.
Here sacred animals (ibis, crocodile,
falcons) were bred – in order to be killed
and their embalmed remains stored in
underground tombs. These are still being
Tomb records show 5358 cattle, 1305 oryx,
1135 gazelles, 1244 antelopes, + addex,
probably all from lower Egypt. Ptolemy II
(283-246 BC) introduced the chimpanzee
and a 45 ft python (?).
Zoo history contd..
Alexander the Great added to
zoo history Indian spp.:
tigers, peafowl, parrots.
The romans used large number
of animals, mainly to fight
with armed humans. Their
taste for lions probably
contributed to the extension
of the Sahara!
Charlemagne, William the
conqueror and Holy Roman
Emperor Frederick II had
extensive animal collections.
Public zoos
It was only in Victorian times that public zoos became
available – previously the collections had all been private.
These Victorian zoos were pleasure gardens, with animals
sometimes available for poking with sticks. They were
simply a drain on wild populations – little successful
The most famous victorian collector was Carl Hagenbeck,
but the capture methods were often brutal. (1 baby gorilla =
10 dead adults).
'For every good zoo in the world there are bad
ones that no defense can justify. Any zoo
where animals are impoverished should be
changed or abolished.' Sheldon Campbell,
Post-Victorian zoos
Rather little changed in the philosophy of
zoo keeping from Victorian times until
the 1960s, except that animals tended to
be given more space, and opportunities
to poke them with sticks gave way to
some respect.
Zoos were for entertainment – keeping
big “classic” species – tigers, elephants,
camels etc.
This phase of zoos gave us at least one
modern phrase: “Jumbo” was an
elephant at London zoo for many years,
and went into the language.
Gerald Durrell
The change in attitudes can be
dated to one man: Gerald Durrell,
who introduced the idea that zoos
should aim to conserve
endangered species. His zoo on
Jersey tended to avoid the big
classic zoo animals, instead
keeping breeding populations of
endangered species.
If you haven’t read his books –
you must!!!
At first his ideas were met with
scepticism by the zoo-keeping
community, but are now
RIP 30-1-1995
Gerald Durrell
Started by collecting animals for other zoos, described in books
such as ‘The Bafut Beagles’ (Cameroon) and ‘The Whispering
land’ (South America).
Set up his own zoo at Les Augres, Jersey, where he ran
programmed to conserve many endangered animals.
One story among many: He had a colony of lowland gorillas,
who dominant male was called Jambo. These lived in a
sunken enclosure. One day a small boy fell over the edge,
and ended up up the gorilla pit with concussion. Jambo
strolled over, picked up the boy, and held him in a protective
cuddle until keepers came to take to boy to hospital.
GD was also known for exposing crooked international animal
dealers. He reported how he was once offered a giant panda.
On protesting that this would be impossible under
import/export regulations, the dealer explained that the usual
practice was to paint the animal black then call it a black bear.
The import/export regulations in question
are called CITES. You should know
about CITES.
CITES - convention on international trade in
Endangered species. Most major nations
have signed up (excluding Taiwan), though
enforcement standards vary.
Appendix 1 - no trade allowed.
Appendix 2 - strictly controlled trade.
There is much biennial debate about which
species should be classified where.
Elephants remain on appendix 1, to the
annoyance of some African countries with an
elephant problem.
Not just animals – a few timbers, and a fish
(Atlantic bluefin tuna).
The lifeboat function
Already there are several species
which would be extinct were it not
for zoos.
 In the future this list can only
expand – rhinos, tigers, great apes
may all become candidates for this
sad status in the next 50 years.
 I want to spend a few minutes
exploring the story behind some of
these species.
Chronologically the first such species
was Pere david’s deer, mentioned in a
previous lecture, but this salvation was
The first deliberate use of zoos to
prevent extinction was the Arabian oryx,
always confined to the searing deserts of
the Arabian empty quarter (Rub'al Khali).
It is thought to be the origin of the
unicorn legend (when seen side on at
distance the horns appear to merge).
It never needs to drink water, relying on
juices in its plant food.
It was traditionally hunted by the Bedouin
as a test of manhood. This was OK in
the days of bows and spears, but when
they started using fleets of landrovers
with mounted machine guns, the species
numbers went into serious decline.
Oryx extinction in the wild
In 1960 ruling members of Qatari tribe
crossed 500 miles open desert in
specially equipped motorcade, to shoot
28 oryx with submachine guns.
FFPS realised that the sp. could only
be saved by getting animals out of
Capture party took nets, planes and
jeeps – no tranquiliser darts then,
and caught 4 animals (one died of
capture shock soon after).
Last wild animals were shot in 1972.
World ppn was then 15, the other 12
being zoo stock.
Oryx survival
These 15 animals were brought together
in a special enclosure in Phoenix,
Arizona. ($ from a US hunting club).
At this stage an outbreak of foot&mouth
would have taken out the species.
1st 6 calves born were male – useless.
Corner was turned in 1966 with a female
By 1977 herd was 60 strong on 2 sites.
These are now widely held in world zoos,
and are being re-introduced to the wild,
in Oman.
The FFPS magazine is today called
Oryx, in memory of this first successful
species rescue.
Californian condor
This is a pleistocene hang-over: It evolved to feed on
carrion of big herds of herbivores such as bison.
Bison were nearly exterminated (to starve native
americans), reducing condor populations drastically.
By the mid 1980s the species was confined to the Sierra
Nevada mountains in California, and down to 5 birds in the
wild (24 in zoos by then).
Survivors suffered shotgun wounds and lead poisoning –
decision was made to capture the entire wild population.
The US Sierra club (similar to FoE) sued the US
government over this, arguing it better to let the species go
extinct rather than keep it in zoos.
It worked!
These birds bred well in zoos, by 1992
population was > 60, and decision was
made to re-introduce them.
Young condors never saw people – were
fed with a condor-head glove.
Some have successfully returned to the
wild, but others (in the Sespe corridor) hit
power lines, or drink antifreeze.
Young birds who settle in the Sespe area
are re-captured, but some have settled in
safer wilder country – they may make it!
Zoos really have helped
Species that would be extinct were it not
for zoos:
Pere David’s deer
Arabian Oryx
Californian condor
Przewalski's wild horse
….These might have managed, but certainly
benefitted from release schemes:
Mauritius kestrel
Hawaiian goose (Ne-ne)
The long-term goal:
Of zoo-based conservation is to
release animals back to the wild.
This assumes suitable habitat
2 big problems to overcome:
re-training animals to survive in the
 Genetic management
Assumes suitable habitat exists.
You can’t restore cultural
knowledge – apes particularly rely
on cultural transmission.
Seems to work best with species
whose behaviour is simple and
unlearned – herbivores such as
deer re-introduce well.
Why capture the last
wild specimens?
Both in the case of the Arabian oryx and
the californian condor, wild animals were
captured when there was a zoo
population. Why bother?
Genetics – you should aim to preserve
as much genetic variety as possible.
This is a deeply serious and complex
issue, that will require me to recapitulate
some basic genetics.
Big topic – I need to recapitulate a little basic genetics with you.
All vertebrates contain 2 sets of genes, one from their father
and one from their mother.
Thus for any given gene function (hair colour, a given enzyme)
animals have two different genes to do the job.
Normally both versions contribute.
If one version is faulty and does not work, the second copy is
relied on. Only when both copies are faulty does the problem
become manifest – such genes are said to be recessive.
2 functional
all is well
1 functional
A a copy:
all is well
a a
No functional
copies: a genetic
problem appears
The way to get problems
with recessive genes:
Is to encourage matings with close relatives. It
is very likely that this is why most societies
(human and animal) avoid consanguineus
Trouble is – in very small populations it is
unavoidable. This applies especially to zoos,
where a few “compliant” individuals who mate
well tend to dominate the gene pool.
Example – a zoo population of an antelope of
a normally nervous, timid species proved to be
genetically deaf. Fine for staying sane in zoos
– useless for the wild.
Even in the wild, small populations are
vulnerable to genetic problems. Rule of thumb:
popns < 100 animals are liable to stochastic
Genetic bad luck
Stochastic extinction refers to the effect
by which a small population goes extinct
by an accumulation of random bad luck.
A surplus of males will reduce future
population size – big deviations from
50:50 are much more likely in small
There is a genetic ratchet: the gene pool
can get smaller, but can’t enlarge. By
chance, genes become eliminated.
(Gene pools become gene puddles )
The more inbred a population, the less
likely it is to survive disease, habitat
change etc.
Population bottlenecks
There are several examples known of populations that have
come through a bottleneck, and emerged with some odd
Florida puma – 30 left, all with bent tip of tail, 90% faulty
sperm, undescended testicles…
Californian sea lion and sea otter both show very reduced
genetic diversity and morphological changes
Recovery – but
highly inbred.
A textbook example: The Cheetah
Acinonyx jubatus: This is the fastest land animal alive, peaking at
It lacks retractile claws. Keepers find it to be less intelligent than
other big cats. Zoos have always found it a hard species to breed.
Akbarthe great of India had 1000 cheetahs captured for use as hunting
animals, and was desperate to get them to breed. they were even
given the run of the palace gardens, but even so only 1 litter of cubs
ever appeared.
They are now bred in zoos, sporadically. Their fertility is low – 70%
sperm are faulty (vs 30% in most cats), and infant mortality high.
Because of a bottleneck:
Genetic tests on cheetahs looked for variation in 52
enzymes – and found NO VARIATION AT ALL in these 52
loci. This was unheard-of in any sexual population –
these animals were virtually clones.
It proved possible to transplant skin from one cheetah to
another, randomly chosen adult!
This species went through a desperate bottleneck. DNA
analyses suggest that the population was down to 1
female + her cub, about 10,000 BP. (At the same time
another species of Acinonyx went extinct).
Just by luck, this family had no lethal recessives, + a
superb body design for extreme speed – they hung on.
(An interesting thought: another species showing
evidence of a genetic bottleneck, and which has lots of
odd features – Homo sapiens! There is more genetic
variation in 1 troop of chimpanzees that the entire human
Stud books
Zoos must aim to minimise loss of genetic
Oddly, the best way to do this for the long
term is to freeze gametes – no loss at all.
Any small sexual population will lose genes.
Next best is to use computers to keep track
of the heritage of all known individuals, and
use this to dictate who mates with whom to
minimise inbreeding.
These databases are known as stud books,
and are now maintained for many of the
critically endangered species in zoos.
This is why we capture wild individuals –
their DNA is needed to maximise diversity in
the long-term gene pool.
The ark image
Conservationists worry about the planetary
“demographic winter”, in which steadily growing
human populations squeeze out all large pristine
natural habitats. In this case zoos must act as
arks to carry species through time, until suitable
habitat is re-created.
We will lose species under this model – some life
forms just can’t be conserved.
use of planetary
Things we can’t save in zoos:
>99.9% of invertebrates, or indeed anything that people won’t
pay to see!
species unable to survive without a host extinct in the wild: ie
the passenger pigeon feather louse. (Note that zoos control
Most rainforest plants (for practical reasons).
Species that won’t breed in captivity:
mountain gorilla
sumatran rhinoceros
+/-giant panda
Sumatran (hairy) rhinoceros
Dicerorhinus sumatrensis