VAS1809 William Mountjoy - Southern Campaign American

Université Rennes 1 — UE Communication scientifique
Stage virtuel à Aarvård
Résumé — ce document contient la plupart des éléments nécessaires pour rédiger
votre rapport de stage virtuel à Aarvård (la seule exception concerne les tableaux
de données qui vous seront fournis séparément sous forme de fichier Excel et avec
leur analyse statistique). Il se compose de deux parties. La première partie n'est
pas sérieuse et figure juste ici pour planter le décor et vous distraire un peu. Vous
pouvez donc la zapper totalement si vous le souhaitez sans aucun dommage à
redouter concernant votre future note. La seconde partie est au contraire très
sérieuse et contient les éléments que vous devrez impérativement utiliser pour la
rédaction de votre rapport. Bonne lecture !
Pour toute question sur l'UE elle même : [email protected]
Pour toute question que vous poseriez à un maître de stage : [email protected]
(écrivez-lui en anglais, ça fait partie du jeu).
Sommaire
Première partie
L'offre de stage qui vous enverra à l'université d'Aarvård
Miko Nunaatuk vous souhaite la bienvenue au Santaklaus Institute
Quelques vues photographiques de votre université d'accueil
Lexique Thulaavik, ça peut toujours servir
La passionnante histoire de l'université d'Aarvård
La non moins passionnante biographie de son fondateur
Quelques vues de Aarvård au temps des pionniers
Interview de Miko Nunaatuk
La page web personnelle de Miko
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15
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17
Deuxième partie
La seule source (fictive) de biblio sur votre espèce d'étude
Informations utiles sur l'équipement de votre labo d'accueil
Description de vos manips, vital pour la rédaction de votre M&M
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The very mysterious case of
the Ouessant fly
UE Bio 818 Communication Scientifique
D. Poinsot
The very mysterious case of the Ouessant fly
2
Santaklaus Wildlife Institute, Aarvård University, Greenland
Lab internship position available for three month
(Starting: January 15th, 2014)
Behavioural mating isolation and larval competition between two Drosophila species
Context: Drosophilids are the well known fruit flies developing from decaying vegetal
material, the most famous being the laboratory model Drosophila melanogaster, which is
found worldwide. We have discovered a new drosophilid species (D. enezeusae) which is
wingless and strictly endemic to Ouessant (Enez Eusa, in Briton), a small windy island near
the French Atlantic coast. Very surprisingly, D. melanogaster itself seems almost absent from
this island.
Project outline: The quasi absence of the cosmopolitan D. melanogaster from Ouessant as
well as its obvious morphologic proximity with D. enezeusae are very puzzling. Your project
will investigate whether the two species are isolated from a behavioural point of view, and
you will determine to what extent their larvae show negative interactions when in competition
for food. In practice, (i) you will observe the behaviour of males toward the odour of females
from their own or the other species using a Y-shaped olfactometer, (ii) you will observe
courtship and mating behaviours during intra and interspecific encounters, (iii) finally, you
will check whether larvo-nymphal survival rate and adult fresh weight are affected when
larvae of both species grow in monospecific or heterospecific groups, in conditions when food
is limiting or not.
Job profile: the successful applicant will have a BSc in biology and a keen interest for
behaviour and evolution. Previous experience with insect rearing and some patience
(repetitive observations must be made) are desirable. The ability to quickly distinguish a polar
bear from a heap of snow might also be useful when walking on the campus.
Contact
Dr. Miko Nunaatuk
Santaklaus Wildlife Institute,
Aarvård University,
10 Harfang Lane, Aarvård, Greenland
[email protected]
D. Poinsot
The very mysterious case of the Ouessant fly
3
Dr. Miko Nunaatuk
Santaklaus Wildlife Institute,
Aarvård University,
10 Harfang Lane, Aarvård, Greenland
25 miles north of Umaatuktituk, January the 1st, 2014
Dear trainee,
A happy new year to you! I am very glad that you accepted this internship position and on
behalf of all the staff I wish you a very good stay at the Santaklaus Wildlife Institute (which
you will very rapidly call ―Santa‖ as everyone else). Wuk Qaamanassut, our caretaker, has
certainly shown you into your room by now, and he has explained to you that the solid steel
bars sealed to your window frames are not here to prevent your escape but rather to forbid
rogue bears smashing their way in without being invited to. He also told you that because of
those beautiful but dangerous neighbours it is strictly forbidden to wander alone on the
campus after dark. Wuk also gave you a blanket for your bed. You may need it; it can get a bit
cool at night.
I will have the pleasure of being your supervisor for the duration of your internship, during
which you will study behavioural traits in adult and larvae D. enezeusae when confronted
with the closely related species D. melanogaster as previously agreed. Unfortunately, you will
have to accept a remote supervision, because I have just been drafted to take part in the big
decennial bear census, which means that for the next three month I will be on the move
counting polar bears during their yearly migration, which means that I will not have the
opportunity to meet you face to face. Fortunately, I have access to my e-mails via satellite
link, so we can communicate anyway. Because weather conditions are a bit rough here, the
connection can be erratic, especially during aurora borealis flares, so do not despair if I do not
reply your requests immediately. You may ask me any questions you would ask to your
supervisor but I cannot correct the paper for your exam: I do not read French at all! Of course,
do not hesitate to ask other Aarvård students for advice about everyday questions such as
―The ink of my fountain pen has frozen solid! Do you know where I could buy pencils like
those you use?‖.
I wish you a good stay up here and please... Aargåff! (:))
Cheers,
Miko
You can contact me anytime at [email protected]
D. Poinsot
The very mysterious case of the Ouessant fly
4
Part One
Introducing Aarvard University
Notice: this first part is not necessary at all to write your exam paper. It is just
here to create the atmosphere of a "real" internship. We hope you will enjoy it all
the same.
D. Poinsot
The very mysterious case of the Ouessant fly
5
Aarvård today
Aarvård campus in summer and in winter
This may be you in a short while…
If you see this by the window, stay indoors!
Two different ways to take a break after lab experiments in Aarvård University
D. Poinsot
The very mysterious case of the Ouessant fly
6
A primer of the Thulaavik language
Everyone at Santa speaks fluent English and you should not have any
communication problem here. However, native students and staff will insist on also
using (and making jokes at your expense) in Thulaavik. Therefore, learning a few
strategic words and expressions would certainly help you a lot in making friends with
the locals and enjoying a playful atmosphere during your stay with us.
Aar
Bear
Vømir
Beer
Dåk
[1] Yes; [2] I completely agree
[1] No; [2] Don‘t even think about it
Ked
Kawåntrøp!
Nonsense!
Børdeiluk!
Good heavens!
Rü
Frozen cod with fried ice (traditional dish)
Fåar
A delicious milk and eggs cake
Køuignamåanutuq
A very caloric survival cake made of seal fat and sugar
marinated in whale oil (some people add a pinch of flour,
purists don‘t).
Vapøwuq
Ether
Dodomoochvapøwuq Etheriser (used to anaesthetize flies)
Kuk
Snow
Finnkuk
Powdery snow
Krakuk
Old snow with a crusty surface
Refinnkrakuk
New powdery snow fallen on old crusty snow
Mortkuk
Water (literally ―snow that is not snow anymore‖)
Tregrokuk
A very large amount of snow indeed
Hjaerkuk
Pristine snow accumulated on the wind-shielded side of rocks
and shining like diamonds under the winter moon. A classical
theme of Thulaavik romantic poetry
Splotchkuk
Snow which has been both vomited and urinated on. This very
special kind of snow is not uncommon near student‘s lodging
halls on late Thursday evenings. Very rarely – if ever –
mentioned in Thulaavik romantic poetry, splotchkuk is on the
other hand omnipresent in raucous Inuit drinking songs.
Aarkuk
A sleeping bear which you had most unfortunately mistaken for
a large heap of snow. Often used metaphorically to mean
―violent and unexpected death‖ in Thulaavik literature.
A Short Thulaavik phrasebook
Wandering on the campus
Aargåff!
Kedj boutik piftuq grek då ?
D. Poinsot
Beware of the bear! (this happens to be the shortest
grammatically correct sentence in Thulaavik)
Isn‘t it a bit of your frozen nose I see on the ground?
(traditional joke used to tease newcomers to the arctic)
The very mysterious case of the Ouessant fly
7
Going out to the pub
Onvaø Rü?
Ked, jeveij vømir
Would you care for some frozen cod and fried ice?
No thanks, I‘ll just have a beer
A few hours later, still at the pub
Yuk? Anpåas me aarpoum
Oh yeah ? Well, only last year, I shot a bear which was
aak trogrø !
at least that big!
Kedis voåar Hjaerkuk
How about going out to watch the pure white snow
søluuntuk ?
twinkling under the winter moon? (a subtle proposition
to get to know each other better in private)
Kevuut påas Hjaernotche
Would you fancy spending the next four-month-night
apoåal me Aarpø ?
naked on a bearskin with me? (a more direct approach)
In the lab
Dodomoochvapøwuq me
øglik ?
drosophila vieij metuk påar ?
Børdeiluk ! somaaksgreløtuk
aaki vapowuq ked vapo !
Be kretinuk drosophila
køelceltuq -15°C termøk ?
Thulaavik proverbs
Tregrøkuk met pifnoår Aar
guesstuuk
Aerst trøil, dert amsooq
Grenekuk, Frenekuk
D. Poinsot
Has anyone seen my etherizer?
Would you have some spare drosophila bottles for me?
Good heavens! It‘s so darn cold in here that my ether
can‘t evaporate!
Who the hell modified the settings of the thermostatic
drosophila rearing room to -15°C???
A large snow heap with a black nose is most probably a
bear (a fine example of old Inuit wisdom)
First the hole, then the line (ice fishing proverb)
Snow in November, snow in December (one of the
many, many proverbs about snow)
The very mysterious case of the Ouessant fly
8
Aarvård History
Pikomiko, the man who saw the bear
How and when Aarvård was really founded is — and will remain — a mystery.
However, Thulaavik shamans have been repeating for centuries the legend of its
founder, and here it is: Once upon a time, there was a courageous Thulaavik chief
and fine seal hunter called Pikomiko (―Miko the very little‖) because of his diminutive
size. One day that he had ventured far away on the pack, Pikomiko was surprised by
a deadly blizzard. To save his life, he hastened to dig a hole in the snow
accumulated at the base of a snow hill protected from the wind by a large block of
ice. Unfortunately, ―someone‖ else had had the same idea before, and Pikomiko fell
right through the ceiling of the den where a fierce female bear was nursing her two
pups. Realising that his last hour (or, to be more precise, his last tenth of a second)
had come, the small hunter bravely drew out his trusted hunting knife and prepared
for a desperate last fight during which he was guaranteed to be shred to pieces.
However, the female bear had been so startled by Pikomiko‘s sudden irruption that
she collapsed and died on the spot, victim of a heart attack (a sad but not uncommon
consequence of eating too much polysaturated animal fat, please make a note of
this, little children).
Pikomiko and the Bear (traditional inuit carving on a giant squid
bladder stone, Thule Museum of traditional Inuit Fine Arts)
Convinced that the Great Bear (Inuit‘s supreme divinity) had miraculously saved him
from a certain death, Pikomiko adopted the two bear pups as his own sons and
swore that never again would his tribe hunt bears. To prove it, he moved the
Thulaavik base camp close to the coast, right into the path of the polar bear migration
route, to mark the fact that bears and Thulaavik people were now of the same blood.
To inform his new blood brothers that they would forever be welcome, the camp was
called Aarvård (―bear camp‖). Several centuries later, Aarvård inhabitants would
much prefer that their city does not lie straight in the middle of a polar bear migration
route, but on the other hand they have grown into a close knit and watchful
community.
D. Poinsot
The very mysterious case of the Ouessant fly
9
Viking invasions
Aarvård is reliably recorded in history for the first time in the 11th century, at the time
when it was discovered by a Viking expedition. The genesis of this trip was initially an
attempt at ransacking the newly discovered Vinland (North America). For that
purpose, the three most terrible Viking warlords of the far North decided to unite
forces. Since they were the most dreaded warriors of their time, History has duly
noted their names for posterity: Haarken the Destructor, Harulf the Deathblower, and
Harald the Birdwatcher. However, things did not turn out as they had been planned.
The day of departure had been carefully chosen, as usual, to avoid offending the
many and susceptible Gods, and also to allow everyone to attend the 56th final game
of the Nordic herring barrel throwing competition that took place every three years in
Guteberg. On D-day, the men were all on the departure pier, ready to go and ransack
the new continent. Haarken and Harulf were there since dawn, but Harald the
Birdwatcher was nowhere to be seen. He was still at home, and so busy explaining to
his servants how to take care of his pet sparrows during his absence that it was mid
afternoon when he finally turned up. Furious, Haarken and Harulf had already left the
port and their sails were mere little dots on the horizon. Harald had to wait for the
next high tide and finally embarked with his men twelve full hours after his two
warlord colleagues. By an irony history is fond of, these few hours of delay would
both save his life and change his destiny forever. Within view of the coast of Iceland,
Haarken and Harulf were surprised by a terrible hurricane which sunk their boats.
None survived.
The departure of Harald the Birdwatcher's expedition according to the
Aradraggha tapestry (notice that more than three boats are represented, for
emphasis. Notice also the birds, a symbolic representation of Harald's
nickname). National History Museum of Brooghaven, Denmark.
Arriving at the same place he day after, little did Harald know that the boats he was
looking for on the horizon were in fact several hundreds of fathoms below him,
resting forever on the bottom of the ocean. The tail of the tempest that had sunk
them blew him north for several hundreds of miles and he found himself lost in the
middle of an iceberg field. The crew was awed by the size of these mountains of ice,
and to make matters worse a dense icy fog fell on the expedition. For three more
days, they were lost and half frozen, waiting for their certain death when one of the
iceberg would sooner or later crack their hull open when, on the morning of the fourth
day, they heard a voice calling. The sea was empty and Harald‘s men were already
speaking about evil spirits, when they had the surprise to discover an old and smiling
D. Poinsot
The very mysterious case of the Ouessant fly
10
man in a tiny boat which was pointy at both ends. This was no bad evil but more
simply old Tiuk Inuuqtitak fishing squid for dinner in Aarvård bay. Thus was Aarvård
discovered by the western world. However, it was to remain unknown for several
more centuries since Harald and his men never came back. Indeed, a few hours only
after their arrival, the drakkar was already blocked by ice. Later this winter, the
pressure of the pack was too much for its tar-jointed planks and the hull was crushed
with a terrific cracking noise. Forced to adopt their new home for good, Harald and
his men took wives in Aarvård. The slow blending of the inuit and Viking customs led
to a new culture, which explains why the Thulaavik language stands unique among
inuit idioms in that it is a mixture or true inuktituq and Old Norse, hence the presence
of typical Viking letters such as å or ø.
Wruk the dragon, a creature from the rich
Thulaavik bestiary. According to the legend, it is
inspired from the decoration of the sail aboard
Harald‘s boat, the Black Wren. (carved walrus
ivory, Aarvard History Museum)
D. Poinsot
The very mysterious case of the Ouessant fly
11
Santaklaus, the man behind the institute
Jack 'Santaklaus' Williamson was conceived in 1816 in Portsmouth, England, but
born in Churchill, Canada, as a result of being the illegitimate son of the – then
adolescent – future English Earl of S*** and Emy 'Applebottom' Williamson, the
daughter of a poor periwinkle harvester. Indeed, his young highness had become
pretty intimate (to put it mildly) with Emy Williamson after a popular dance party
celebrating the first anniversary of the battle of Waterloo. When the Earl's father was
informed of Emy's pregnancy by his furious future would-be-father-in-law, he
snapped into action and offered cash in exchange for his absolute silence. To be on
the safe side, he also demanded and obtained that the 6-month-pregnant Emy be
sent to Canada where she would receive a stipend to sustain her and the baby.
Accordingly, "Jack no-father", as he was nicknamed by his schoolmates, grew up
in the snowy streets of Churchill where his professors at the St Saskatch boarding
school praised his superb drawing skills and keen sense of observation, as well as a
gift for Latin, which at the time formed the pre-requisite to do anything serious in the
Good Society. However, Jack's scholarly education came to an abrupt and tragic end
when his mother died from pneumonia during the hard winter of 1829. At age 12,
Jack was an orphan for good, in a society which was fortunately not as rigid as
Victorian England, but yet very hard on poor people.
Jack survived as a newspaper boy for a few years during which he read a great
deal and acquired a remarkably broad culture for a person of his modest condition,
but pay was miserable and at age 16 he boldly joined the powerful Hudson Bay
Company to become a trapper. Despite of his enthusiasm and natural endurance,
young Jack knew nothing about life in the open and had to learn his trade following
older experts, doing the hardest part of the work for a small percentage of their gains.
However, he learned the ropes very fast and his reputation as marksman started to
grow.
'Tobacco Pete', pictured here in studio just after his retirement in 1836. He was
one of Jack's hard-nosed professors of wildlife, and a living legend in his own
days. How he was capable of approaching even the most vigilant creatures of
the wild while exhaling such a pungent tobacco smell will forever remain a
mystery.
D. Poinsot
The very mysterious case of the Ouessant fly
12
Jack "Santaklaus" Williamson in 1859. He was
then renowned all over Canada as the best
trapper alive. (Kodiakhrome process, Thule
National Gallery)
However, what put Jack Williamson fundamentally apart from his many trapping
colleagues roaming the uncharted immensity of the northern territories in search for
valuable furs was his genuine interest for the beauty and adaptations of the creatures
he was running after. All along his career, he kept a diary of his observations which
he illustrated with hundreds of precise silver point drawings as well as several
watercolors for which he spend what was for him a fortune on expensive artist-quality
paint and paper (although he obviously made his wolf and sable hair brushes
himself). The originals of these documents are now the most precious pieces kept at
the Aarvård natural history museum. Even more unique among northern trappers of
the time, Jack's real writing skills and his knowledge of the publication process
allowed him to have some of his notes on the behavior of the local fauna accepted in
respected scientific gazettes such as the Bulletin of the Saskatchewan Society for the
Advancement of Science.
His well deserved reputation as a northern wildlife expert led Jack to be solicited
regularly to guide scientific expeditions. In particular, he led in 1857 the exploration of
Ellesmere island, where he made the first description of arctic wolves hunting
techniques in their natural environment. During this expedition, he had the
opportunity to meet Inuit people for the first time as the team spent the winter in
Thule (north Greenland), where he learned a lot about native survival techniques in
extreme conditions. The following year, Jack was then chosen to accompany one of
the first trans Greenland expedition, at the end of which the isolated village of
Aarvård had its first contact with the Western world. There, Jack literally fell in love
with the place, and with a charming inuit girl called Nanooka Qmutluq. Unfortunately,
the demands of the expedition meant that Jack had to leave, but he promised to
come back as soon as possible.
On the way Back to Churchill, following the eastern Greenland coast, Jack noticed
that polar bears could be seen almost every day, and that they were all heading
south. He then realized that the expedition was following a migration route, a
migration which was known by inuits for ages but had never been actually mapped. It
D. Poinsot
The very mysterious case of the Ouessant fly
13
was decided to follow the bears, which led the expedition to the southernmost tip of
Greenland. Jack then reasoned with common sense that these were not the polar
bears seen every year in Churchill, meaning that polar bears might be separated in
more than one population.
Back home at last in 1860 after three years of hardship, Jack was probably the
one and only trapper of that century to buy a copy of Darwin's On the origin of
species and one of the very rare men of his time to appreciate with an expert eye the
enormous amount of fieldwork and careful observations carried out by its author. He
emitted, however, a thundering roar of laugher when discovering Darwin's hypothesis
that the whale descended from the polar bear's "habit of swimming with his mouth
open to capture insects at the surface of the water". Jack had skinned a sufficiently
large number of polar bears and seen enough corpses of whales, including fossil
bones, to realize that it was quite a remote possibility, to say the least. A direct man
as always, he did not hesitate to write Darwin a long letter about it, to which he joined
a number of his personal observations of polar bear stomach contents (remarkably
devoid of insects), and some of his drawings of fossil whale skulls.
Charles Darwin toward the end of his
life. At the time, his scientific correspondence with Jack ‗Santaklaus‘
Wiliamson filled two volumes.
Jack ‗Santaklaus‘ Williamson at the turn
of the century. The 80 years old extrapper had become the respected
founder of the first university ever above
the polar circle. (Whale oil on canvas,
Greenland National Gallery, Thule).
An excellent field naturalist himself, Darwin was impressed by the knowledgeable
trapper and a long correspondence between the two men ensued, which was going
to lay the foundations of a project that Jack was nurturing in the secret of his heart
but did not have the funds to start. Then, just at the right moment, Jack, literally,
struck gold. He was trapping in Klondike when he discovered what was to become
one of the most productive gold mine of the area for the years to come. After a hard
fought legal battle against local barons, Jack managed to establish his claim to his
discovery. Now an extremely rich man at only 50, the most famous Canadian trapper
of his time did not retire in the sunny south Carolina but on the contrary headed
straight up north and boldly started a completely new career.
Indeed, Jack loaded as much top-level scientific equipment as was possible in an
old whale boat (the Stern) and set sail to Aarvård, where he arrived after a heroic
navigation among icebergs in august 1866. Then, he did what nobody else but him
would have dared to do : laying the foundations of a polar wildlife research institute in
the middle of nowhere.
D. Poinsot
The very mysterious case of the Ouessant fly
14
Aarvård at the turn of the century
A group of picturesque natives
discussing about next seal hunting
season? Well, think again. These are
some of the participants of the
international 1902 polar ecology
conference. On the left (with snow
googles) Eltiak Knusquunak, then
director of the Santaklaus Wildlife
institute and first dean of Aarvård
University. He will be remembered as
the best specialist of polar bear
behaviour of the 20th century.
Nanook Qmatuklivik, then a
post-doctorate fellow at the
Santa', pictured here on a field
trip to collect krill samples
somewhere in Aarvård bay in
the early 1920's. He became
the youngest Aarvård professor
ever, at age 29, and was a
recognized pioneer in polar
marine food-chains.
D. Poinsot
The very mysterious case of the Ouessant fly
15
Aarvård Weekly
Founded in 1875
A new fruit fly species discovered in France by an Aarvård scientist
An interview with Miko Nunaatuk
LGL — Dr Nunaatuk, what exactly have you discovered in Ouessant this summer?
MN — A new Drosophila species, which has been named Drosophila enezeusae. Drosophilas are the
very small flies that you see hovering over ripe fruits in summer and autumn in temperate and tropical
regions, even in supermarkets. They are especially fond of melon and grapes.
LGL — are they dangerous?
MN — Not at all. Unlike so called ―domestic‖ or ―dung‖ flies, fruit flies are only interested in fermenting
fruits. They would never land on dung or rotten meat (or a wound!), so they are not carriers of
dangerous microbes. In fact, like some people, they are mostly attracted by the smell of... alcohol
[laughs]
LGL — Are these the small flies flying around sangria bowls at barbecue parties?
MN — Exactly. In the wild, Drosophilas lay their eggs in over-ripe fruits because their larvae eat the
flesh of fermenting fruits. As a result, drosophila larvae are extremely resistant to alcohol, and adults
use its smell to find suitable sites to lay their eggs. They do not need a full sangria bowl though:
Drosophilas are so minute that they can develop in the few drops left at the bottom of an empty wine
or beer bottle.
LGL — A sort of wine fly, then?
MN — Indeed. In French the fruit fly Drosophila melanogaster is precisely called ―mouche du vinaigre‖
(i.e. ―vinegar fly‖), which proves that the proverb saying that flies cannot be caught using vinegar is...
completely false! [laughs].
LGL — What makes Drosophila so interesting to science?
MN — Their small size means that Drosophilas develop very fast. You can have a generation in less
than ten days at 25°C. As a result, a lot of important genetic discoveries (e.g. mutations) have been
made using these flies. What is less known is that the first animal launched in outer space in a rocket
was not Laika the famous Russian female dog but... some American Drosophila melanogaster! This
fruit fly is the first animal which genome has been entirely known. However, I am mostly interested in
Drosophila ecology and behaviour, i.e. the way different drosophila species interact with their
environment.
LGL — What on earth gave you the idea to come and look for a new species in Ouessant?
MN — Good question! [laughs] In fact, as with many scientific discoveries, this one was largely due to
chance. I was in Europe for my holidays when I stumbled across my old friend Trevor McIntosh buying
fresh lobsters in Lampaul‘s port! Put two scientists together, and within five minutes they are talking
about science, of course. Since we are both interested in drosophila ecology (I met Trevor in Scotland
during my thesis on drosophila), we decided to set a few traps to see which species were present on
your island, just out of curiosity. And bingo! We hit on this new species! We were so excited that I
spent the rest of my vacation collecting flies in Brittany to try finding other individuals. My wife nearly
killed me for that. How I avoided getting a divorce this summer is anyone‘s guess [laughs]
LGL — You say you used traps? What kind of traps do you use to capture fruit flies?
MN — All you need to ―capture‖ drosophilas is any kind of small containers where you put ripe fruits.
Hang those in the shade for a few days and if there are fruit flies around, believe me, they will find
D. Poinsot
The very mysterious case of the Ouessant fly
16
them and lay dozens of eggs! Sure enough, we captured fruit flies on your island, and they all
belonged to this new species, which is extremely strange!
LGL — What is so strange?
MN — We would have expected to capture more than one species. More precisely, we were expecting
to find many individuals of the very common species Drosophila melanogaster. On the contrary, in
three weeks of research all over Ouessant we could only find a few of them on fruits sold in a grocery
store. All individuals captured in the open were Drosphila enezeusae, while we could not find a single
D. enezeusae on continental Britanny nor on nearby islands like Hoedic or Belle-Île, and this is
another mystery.
LGL — What about it ?
MN — Drosophila enezeusae appears to exists in Ouessant and nowhere else! (in technical terms we
would call it an endemic species).
LGL — Does it mean it is in danger of extinction?
MN — Absolutely not. The population here in Ouessant is extremely strong. You can put a trap
anywhere on the island and catch dozens of them in no time.
LGL — What is the next step in your research on this new species?
MN — Trevor, who works in Europe all year, will continue field sampling and study the species in the
field, so that we learn more about its ecology and life cycle in realistic climatic conditions. I will
concentrate on laboratory work. There are a lot of preliminary experiments to do, and several Master
students will come in my lab in Aarvård, Greenland, to participate in this exciting task this year,
including, by the way, a French student of the University of Rennes.
LGL — Isn‘t it a bit weird that an Inuit scientist studies the ecology of temperate or tropical species in a
Greenland University?
MN — Only if you believe in clichés about Inuit people. Science is not necessarily about what you see
out of the window. Of course, at the Santaklaus Wildlife Institute I have colleagues who study the
diving behaviour of seals or the effect of global warming on tundra lichen reproduction, but I can study
drosophila behavioural ecology there as easily as in Paris or New York. Besides, our climate is a great
advantage since I am authorised to import any species of Drosophila without any heavy quarantine
regulations or sophisticated confinement equipment in our institute.
LGL — Why is that?
MN — If a fly manages to escape from our lab it will immediately freeze to death [laughs]
Translated with permission from La Gazette de Lampaul (August 28th, 2013). Original
interview by Nolwenn Kerdantec © 2013 La Gazette de Lampaul.
D. Poinsot
The very mysterious case of the Ouessant fly
17
http://perso.univ-aarvard.gro/miko.nunaatuk
Miko Nunaatuk’s personal Web page
Ain‘t I cute? These precious ivory snow googles
were a gift from my beloved grandfather,
Ptenko Nunaatuk, on my 16th birthday, the day I
was authorised to lead my first walrus hunt.
Current position: Senior Lecturer, Aarvård University (Biology Dpt., Santaklaus Wildlife Institute)
Teaching responsibilities: Behavioural Ecology (unit Bio 715); Statistical analysis (stats701)
Research interests: I am mostly interested in the way animal behaviour is shaped by ecological
forces such as the interaction with natural enemies or the availability of food resource. My biological
models are in the field of entomology, especially drosophilids (fruit flies)
Short curriculum:
1987
BSc (Hons) in Biology, Aarvård University, Greenland. Final paper: ―Optimal scavenging
behaviour of the arctic silver fox: how close can you get from a hungry polar bear?‖
1989
MSc in Ecology, Winnipeg University, Canada. Final paper: ―Cold weather tactics of the
arctic drosophilid Drosophila svalbardii: optimal foraging in extreme conditions‖
1994
Ecological volunteer, Kerguelen Island. Participation to a scientific mission with the ―Terres
Australes Françaises‖. Study of the feeding habits of an endemic predatory beetle.
1997
PhD. University of Inverness, Scotland. Fellow of the Loch Ness School of Biological
Sciences. Thesis: ―Optimal foraging in drosophilids: how to apply Charnov‘s theorem when
you have the brain of a gnat?‖
Recent publications:
Nunaatuk M & McIntosh T, 2014. Drosophila enezeusae (sp. n.), a wingless drosophilid species from
Ouessant. Proc. Plougastel-Daoulas Acad. Sci. 58:1027-1030. doi:12451.ppdas.547.245
Punaaqnassut K, Noonak J & Nunaatuk M, 2012. Frostbite avoidance in Drosophila saskatchewanae:
when the going gets tough, the tough hides underground. Canadian J. Drosophila Ecol. Evol.
27:256-259. doi: 451.547.cjdee8545
Nunaatuk M., 2011. Drosophilid foraging behaviour: from equatorial rainforests to the toundra. Annu.
Rev. Behav. Entomol. 17:374-392. doi:375.47.arbe245
D. Poinsot
The very mysterious case of the Ouessant fly
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Part Two
And now some real work to do
Important notice: this is the part you must read to write your exam paper.
D. Poinsot
The very mysterious case of the Ouessant fly
19
Proceedings of the Plougastel-Daoulas Academy of Sciences (2014) 58:1027-1031. doi:12451.547.245
SHORT NOTE
Drosophila enezeusae (sp. n.), a wingless drosophilid species from Ouessant
Miko Nunaatuk1 & Trevor McIntosh2
1
2
Santaklaus Wildlife Institute, 10 Harfang Lane, Aarvård, Greenland
Loch Ness School of Biological Sciences, 105 Square Crescent Road, Inverness, Scotland
Abstract — Here we report the discovery of Drosophila enezeusae (sp. n.),
the first apterous drosophilid species ever described, which appears to be
strictly endemic to Ouessant, a small and windy oceanic island a few miles
off the westernmost tip of Brittany, France. Apart from its lack of wings and
smaller size, D. enezeusae is morphologically almost undistinguishable from
D. melanogaster in the female sex, although D. enezeusae males are easily
recognisable by their distinctive genitalia. In Ouessant, D. enezeusae is the
only drosophilid we could find. Quite incredibly, D. melanogaster itself
seems totally absent from the island, except for very rare individuals found
near containers of fruits recently imported from the continent. The reason
why such a widespread species as D. melanogaster has not yet succeeded in
colonizing an island receiving so much traffic from the mainland is deeply
puzzling, and the evolutionary origin of D. enezeusae is not clear.
INTRODUCTION
Drosophilids (Diptera : Drosophilidae) are small fruit flies originating from
the tropics, and counting among them the famous genetic’s lab workhorse
Drosophila melanogaster, the first animal ever to have its genome fully
sequenced. Yet, despite of a century of research and thousands of papers
dealing with this animal model, surprisingly little is known about the basic
ecology and behaviour of drosophilids in the field, although a large number
of species have been described. The current count stands at over 3,000
(Russo et al., 1995), the most recently described species being D. Santomea,
which is endemic to São Tomé island in the Gulf of Guinea and was
discovered at the turn of this century (Lachaise et al., 2000). In this short
note we describe the serendipitous discovery of yet another endemic
species, Drosophila enezeusae (sp. n). Contrary to Drosophila santomea,
which is more than 200 kilometres from the African coast, we found D.
enezeusae nearly on the doorsteps of the many scientific labs housed in the
university of Brest, more precisely on the small windswept French island of
Ouessant, which has been inhabited for centuries and receives tourists by
the thousands every summer. The present note deals with morphological
characters only, the basic life history traits of the new species will be the
subject of a future more ecology-oriented paper.
D. Poinsot
The very mysterious case of the Ouessant fly
20
MATERIAL AND METHODS
The island of Ouessant
Ouessant (48° 28' 00'' N 05° 04' 60'' W in Lampaul) is a small island (4 ×
7km, 1158ha) situated 12 nautical miles (approx. 20km) from the
westernmost tip of Britanny, France. It enjoys a mild oceanic climate
(maximum daily august temperatures: 22°C, minimal February
temperatures: 6°C) with a typical rainfall of 700mm (similar to Paris). On
the other hand, Ouessant is very windy, being subject to 178 days of winds
exceeding Beaufort 4, including serious gale force winds in autumn and
winter. As a result, the vegetation is low (trees are almost absent) and
constituted essentially of a low turf near the coast and moors further inland.
The island is criss-crossed by a network of low stone walls, which are not
maintained as they used to be and are often hidden by brambles overgrowth
(Rubus sp.).
Mammals are rare on the island, but the avian fauna is quite rich both in
marine and migratory species, such as the Northern Fulmar (Fulmarus
glacialis), Great Shearwater (Puffin gravis), European Storm Petrel
(Hydrobates pelagicus) and raptors such as the Osprey (Pandion halietus)
or the emblematic Peregrine falcon (Falco peregrinus), which is observed
nearly all year long (Audevard, 2006). Finally, Ouessant is home of 960
Ouessantins in winter, and receives several thousands of visitors during the
summer season. As far as the historical record shows, it has been inhabited
continuously in historical times, and archaeological evidence suggests a
human presence as early as 1500yrs BC.
Sampling sites
Ouessant being a very small island, the 13 different locations sampled cover
most of the area and are representative of the vegetation cover found. Their
characteristics are described in table 1.
As a second step, nearby continental locations (Brest, PlougastelDaoulas, the Crozon Peninsula) were included in the sampling scheme, as
well as the neighbouring islands of Molène, Hoëdic or Sein. However, not a
single Drosophila enezeusae was captured from this second series of traps
(which yielded a total of 3,428 flies of the genus Drosophila). Accordingly,
this paper will only deal with the Ouessant results.
Sampling method
All sampling in Ouessant was carried out on 5-10 August, 2013. Plastic
bottles (250ml) were fitted with a U shaped aperture on the side and baited
with ripe banana and baker’s yeast. The bottles where left in place for seven
consecutive days, shaded from direct sun to avoid overheating (whenever
possible, they were left dangling under brambles bushes (Rubus rubus).
Upon collection, each trap was immediately sealed with cellotape and adult
flies seen in the bottle were captured with an insect aspirator for
examination under the binocular after light diethyl-ether anaesthesia. The
larvae were left to develop in the shade at ambient temperature (day:2025°C, night:16-18°C) and were identified upon emergence of adults.
D. Poinsot
The very mysterious case of the Ouessant fly
21
Identification
All drosophilids captured in Ouessant were all compared with the reference
Drosophila collection of the first author under a dissecting microscope
(max. magnification of 40x).
RESULTS
A total of 601 drosophilids were collected. With the exception of the trap
placed in the fruits section of Lampaul’s grocery store (where two
Drosophila melanogaster individuals were recovered out of 40 captures,
table 1), all individuals belonged to an apterous and yet unknown species of
the genus Drosophila, which we chose to name Drosophila enezeusae for its
supposed endemic nature (the Breton name of Ouessant is Enez Eusa).
Table 1. Sampling sites and identification of Drosophila sp. captured in Ouessant
(5-10 August 2013). Each site was fitted with a trap baited with ripe banana and
baker's yeast (see text for details)
Location
Characteristics
Individuals recovered
D. enezeusae D. melanogaster
Lampaul 1
Private garden
22
–
Lampaul 2
Grocery store*
38
2
Mez Notariou
Bramble patch
147
–
Locqueltas
Sheep pasture
50
–
Nividic Point
Low coastal turf
3
–
Niou Uhella
Old pasture
15
–
Kergadou
Bramble patch
153
–
Calgrac'h Cove
Low coastal turf
–
–
Stiff Point
Low coastal turf
–
–
Penn Ar Lan
Wetland
17
–
Stang Merdy
Wetland
8
–
Lann ar Grac'h
Moorland
12
–
Penn ar Roc'h Cove
Low coastal turf
4
–
Feunteun Velen
Bramble patch
135
–
* trap left for one night only, at owner's request
599
2
Diagnosis
Apart from its lack of wings, D. enezeusae is extremely similar
morphologically to D. melanogaster in females (figure 1). On the other
hand, D. enezeusae males are readily distinguishable from D. melanogaster
males by their very conspicuous black genital plate.
A comparison of the aedeagus confirms a marked morphological
difference (fig 1 d,e). These data strongly suggest that D. enezeusae is a new
species, although it is obviously very closely related to D. melanogaster.
Another distinguishing character between the two species is the smaller
size in D. enezeusae (it is approximately 20% smaller than D. melanogaster
in both sexes). This reduced size is not due to poor food sources since it is
maintained after several generations in the lab in un-crowded conditions on
high quality medium (data not shown).
D. Poinsot
The very mysterious case of the Ouessant fly
22
b
a
c
d
e
Figure 1. Male (a, b) and female (c) of D. enezeusae. Notice the lack of
wings and the conspicuously large genital plate in the male (arrow). Pannels
(d) and (e) show a comparison between the male genitalia of D. melanogaster
and D. enezeusae, (respectively). Notice in D. enezeusae the very large
genital plate, the broader aedeagus as well as its peculiar trident shape. Bar:
100 m.
Voucher specimens of the new species have been donated to the University
of Brest. Holotypes are kept both at the British Museum (accession number
BMS.251.278.1.695) and the Aarvård University Natural History Museum
(accession number AAR.26.586.984)
DISCUSSION
[not reproduced here so as not to stiffen your creativity when trying to
interpret your own results about the interaction between Wolbachia and the
very mysterious Ouessant fly]
D. Poinsot
The very mysterious case of the Ouessant fly
23
CONCLUSION AND PERSPECTIVES
The discovery of a new Drosophila species brings more questions than it
answers, the first being of course: is it a bona fide species or merely a
subspecies of D. melanogaster? To answer it, crossing experiments with D.
melanogaster will be carried out shortly. Moreover, we will determine
whether the reproductive isolation between these two drosophilids is due to
pre-mating (i.e. behavioural) or post-mating (genetic) factors. If D.
enezeusae is, as we believe, a true species, the question of how its speciation
event took place and the extremely puzzling absence of D. melanogaster on
Ouessant must be investigated.
Acknowledgments
The first author wishes to thank his friend B. Le Garff, whose extensive knowledge of
Ouessant was a great help in discovering what D. enezeusae — if only it existed for real —
might develop on: blackberries. My own initial ―guesstimate‖ (fallen cider apples) was
ridiculous since there are virtually no trees in Ouessant! The skillful hands of T. Frétey and
B. Le Garff were also helpful in strategically altering the genitalia of a genuine South
American drosophila species to create those of D. enezeusae. The (beautiful) original ink
drawings of genitalia are due to Marta Erps Breuer (1902-1977), designer and lab
technician at the Universidade de São Paulo, and a former Bauhaus student.
REFERENCES
Audevard A., 2006. L'année ornithologique. Bulletin Ornithologique Île Ouessant 15:1–
56. [http://audevard.aurelien.free/IMG/pdf/Bulletin-ornitho_Ouessant_2006.pdf]
Lachaise D., Harry M., Solignac M., Lemeunier F., Bénassi V & M.L. Cariou, 2000.
Evolutionary novelties in islands: Drosophila santomea, a new melanogaster sister
species from São Tomé. Proceedings of the Royal Society of London B. 267:1487–1495.
doi:10.1098/rspb.2000.1169
Russo, C.A.M., Takezaki N. & M. Nei, 1995. Molecular phylogeny and divergence times
of Drosophilid species. Molecular Biology and Evolution 12:391–404.
D. Poinsot
The very mysterious case of the Ouessant fly
24
Useful information to get a feel of your virtual experiments.
Basic drosophila lab equipment
Drosophila bottles
Such bottles are typically 250 ml flasks with a wide aperture for easier
manipulation. They are filled with a one-inch layer of drosophila medium
(25ml). The traditional (and most practical) way to close drosophila bottles
is by means of a large cotton wool plug, which can be removed using the
little finger alone if necessary, the rest of the hand being free to manipulate
various objects. For better hand comfort, crude (non hydrophobic) cotton
wool is used.
Drosophila tubes
These vials are typically not more than 15cm high (i.e., short enough to be
put upright under a binocular) with a 2,5cm or wider diameter (i.e. a wide
aperture). They have a flat bottom so that they can safely stand upright on
their own, although they are moved around in bunches of 20 using plastic
vial holders. Each tube holds a one inch layer of drosophila medium (5ml).
Again, the most practical way to close them is by means of a small crude
cotton ball.
Drosophila medium
The medium is the solid food seen at the bottom of bottles and tubes found
in all drosophila labs. Since the days of Thomas Hunt Morgan (who used...
ripe bananas) several dozens of media have been invented, but the basic
components are usually wheat or maize flour and baker's yeast, cooked
together with agar to form a solid layer firmly attached to the bottle, which
can be put upside down and bumped on a rubber mat repeatedly without any
medium falling. Some media use live bakers' yeast, others are axenic
(sterile, at least at the moment when they are put into the bottle). David's
medium (see further below) is an axenic medium.
Rubber mats
Also known as « bottom bumpers », they are small rugs (15x15cm) made
from any soft and bumpy surface (often odd bits of used carpets) which are
put on drosophila lab benches so that the bottom of drosophila bottles or
tubes can be briskly bumped on the bench without breaking. This fast
bumping action is one of the most frequent movement seen in drosophila
labs around the world. Its role is to make all flies fall temporarily at the
bottom of the bottle so that the plug can be open without any drosophila
escaping. This gesture is used in particular when flies need to be masstransferred from an old bottle into a new one to maintain stocks.
Insect "pooters"
They are small « fly aspirators » made of one straight glass tube with an
internal diameter of a few millimetres (enough for a drosophila to be sucked
D. Poinsot
The very mysterious case of the Ouessant fly
25
in) fitted tightly by a long plastic tube which the manipulator holds in
his/her mouth. This aspirator is used to suck a fly in or flush it out, allowing
it to be transferred from one tube to the other without the need to open the
cotton plug (the glass tube is small enough to be inserted while the plug is in
place). Needless to say, the junction between the two tubes is fitted with a
fine fly-proof screen; otherwise drosophila workers would eat a large
number of flies every day.
Etherizers
They are the traditional devices used to anaesthetize (or kill) drosophila.
They are made of a chamber where ether diffuses and into which flies fall
through a funnel. The difference between ether fly anaesthesia and ether fly
murder being only a subtle question of timing, which strongly depends on
the amount of ether put into the apparatus, the temperature of the room and
the experience of the scientist, beginners are guaranteed to involuntarily
slaughter quite a number of innocent flies before they get used to their
etherizer. In modern labs, etherizers tend to be replaced by CO2 flow beds,
but these have a rough surface and when it comes to sort rapidly large
numbers of flies, they are not as efficient as the traditional ceramic white
tile on which you dump your anaesthetised (or dead) flies.
Fly strains in our laboratory
D. enezeusae (wild type)
Our D. enezeusae lab strain was established in August 2013 from more than
a hundred females recovered captured from traps baited with ripe banana
and yeast put in various places on the island of Ouessant during my summer
vacation in France (for a full list of locations see table 1 in Nunaatuk & Mc
Intosh, 2014). Since that time, the strain (known in our lab as « Ouessant
2013 ») is mass-bred here in the entomology lab of the Santaklaus Wildlife
Institute. The strain is maintained on David's axenic medium (David J.,
1962. A new medium for rearing Drosophila in axenic conditions.
Drosophila Information Service 93:28.). We maintain at least 400
reproductive couples per generation to minimize drift and inbreeding.
D. melanogaster (wild type)
Our D. melanogaster lab strain was also established in August 2013 from
more than a hundred females captured from traps baited with over-ripe
carrots put on the balcony of the Paimpont research station, near Rennes.
Since that time, the strain (known in our lab as « Paimpont 2013 ») is massbred as described above.
Summary:
Table 1. Strains to be used during the project
Identification
D. Poinsot
Species
Full strain name
enez
D. enezeusae
Ouessant 13
mel
D. melanogaster
Paimpont 13
The very mysterious case of the Ouessant fly
26
Experiment 1 :
Attraction of males toward the odour of conspecific and heterospecific
virgin females
In all experiments using adults, only use individuals which have been
selected as virgin from the pupal stage and have been put in isolation, one
per 25 ml vial. Pupae are translucid so you can recognize males from female
before they emerge by looking for the sexual combs that males harbor on
their legs.
In this first experiment, you will test whether D. melanogaster and D.
enezeusae virgin males are attracted to pheromones released by virgin
females from the other species. To do so, you will use a two-arms ("Yshaped") olfactometer (see below the quick sketch I made).
The male will be placed at the base of the Y-shaped tube and will receive
two different airflows from each branch of the olfactometer. This airflow
will be air only (control) or air which has passed through a chamber
containing a virgin female (female odour). You will then record the time
spent by the male in each of two meaningful zones : (i) arm A of the
olfactometer, (ii) arm B of the olfactometer. Males will not see the females,
and will not be able to reach them (the arms are obstructed by fine mesh
gauze). You will confront D. melanogaster and D. enezeusae males with the
three following dual choices:
D. Poinsot
The very mysterious case of the Ouessant fly
27
a) virgin D. melanogaster female vs air
b) virgin D. enezeusae female vs air
c) virgin D. melanogaster female vs virgin D. enezeusae female
Here is how you will proceed :
1) check that the airflow of the olfactometer is OFF.
2) Using you fly aspirator, gently put a 3-day old virgin female in chamber
A or B at random (do not use systematically the same chamber for a given
treatment, to avoid position bias).
3) Leave the other chamber empty (case of a test "female vs air") or gently
place a female of the other species in it (case of a test "melanogaster vs
enezeusae").
4) Open the valve and set the airflow to 5cm/s. The air reaching the base of
the olfactometer will now come from both chambers.
5) Using your fly aspirator, gently place a 3-day old virgin male in the
obscured part of the olfactometer (resting area).
8) start your chronometer.
9) When (and if) the male gets out of the obscured resting zone, record the
time spent in each zone : arm A, arm B.
10) After three minutes, stop the recording, remove the male and the female
from the olfactometer and prepare for a new repeat. You will need 20
repeats per treatment.
11) Between different treatments, dismantle the olfactometer, wash the Y
tube and the chambers in soapy hot water and let dry overnight.
12) If the gaz bottle runs empty, call Wuk on extension 6711 and ask for a
new one.
(see next page for experiment 2)
D. Poinsot
The very mysterious case of the Ouessant fly
28
Experiment 2 :
Compared behaviours during conspecific and heterospecific encounters
between virgin males and virgin females
In this experiment, you will test whether D. melanogaster and D. enezeusae
accept to mate with individuals of the other species. To do so, you will
compare the behaviour of homospecific and heterospecific couple of virgin
flies by observing encounters during 30 minutes. You will record the
number of typical courtship behaviour of males as well as the occurence and
duration of mating if it takes place. Here is what you will do in practice :
1) 24h before the experiment, isolate virgin males and females in individual
25ml tubes.
2) With your fly aspirator, gently introduce a virgin female in an
observation chamber (these chambers are made of plexiglas, 10mm in
diameter and 3mm high with a transparent lid and a small hole at the bottom
to introduce flies).
3) wait for one minute for the female to settle in its new environment.
4) With your fly aspirator, gently introduce a virgin male in the chamber,
close the hole and immediately place the observation chamber under a
dissecting microscope.
5) start your chronometer and note (i) the number of attempts of the male to
court the female (the female walks rapidly towards the female, follows her
and then orients 90 degrees from her body, trying to attract her attention by
extending the wing -- if it has any), (ii) the occurence of mating (the male
mounts the female) and, (iii) if a mating occurs, the total duration of the
copulation (time from mounting to dismounting by the male).
6) change or wash in alcool the mating chamber between two couples.
7) repeat 20 times (i.e. observe 20 different couples for each kind of
encounter).
(see next page for experiment 3)
D. Poinsot
The very mysterious case of the Ouessant fly
29
Experiment 3 :
Competition between D. melanogaster and D. enezeusae larvae
In this experiment, you will test the effect of competition between D.
melanogaster and D. enezeusae larvae in two situations : (i) food abundant
and (ii) food scarce. To do so, you will place controlled numbers of first
instar larvae of both species either on a sufficient or an insufficient amount
of food. You will then count the number of adult individuals of each species
to complete sucessfully their development, and weight them using an
ultraprecise Sartorius scale.
1) 48h before the experiment, put at least100 couples of mated flies in a
plexiglas cage with a small Petri dish containting David's medium
(obviously, prepare one cage with D. melanogaster and another for D.
enezeusae). Scratch the medium with a needle beforehand to create grooves
(groves induce oviposition).
2) put the cage in the 25°C thermostated drosophila box so flies are warm
and cozy. In the name of the Great Bear do *not* touch the thermostat of
this box ever, ever, and I mean it. The last trainee who modified this sacred
setting was sentenced to shovel the snow from the lab's door all the way to
the Dean's office as a punition.
3) after 48h exactly, collect first instar larvae delicately with the tip of a
humidified small brush to use them in your experiments.
4) for the "food abundant" condition, put either 20 larvae of one species or
10 larvae of both species in a 25ml vial containing 5ml of David's medium,
this is more than enough for this number of larvae (5ml of David's medium
is sufficient to obtain 100 larvae in good conditions). Close the tube with a
cotton pad and place back at 25°C until emergence (approximately 9 days
later). You will prepare 10 replicate tubes for each treatment (hence 200
larvae per treatment).
5) for the "food scarce" condition, do as above but with 100 larvae (or
50+50) in a vial containing only 1ml of Davids medium. This will create a
severe competition for food, especially during the third instar. Again,
prepare 10 replicate tubes per treatment (hence 1000 larvae per treatment).
6) during the emergence period, you will need to work round the clock
(checking emergences every six hours) so bring a sleeping bag and an alarm
clock to the office, and plenty of coffee (remember that it is forbidden to be
out alone on the campus after dark, because of wandering bears).
7) check vials for emergences every 6h, kill emerging flies using the
etherizer, sort them by species and weight them individually (to 0.01 mg
accuracy) using our Sartorius microscale. Do not spill coffee on the
microscale please, this stuff costs a fortune (the microscale, not the cofee).
D. Poinsot
The very mysterious case of the Ouessant fly
30
Before I forget: here is a quick sketch I made under the microscope: it
compares the mouth hooks (the hard chitinized parts larvae use to feed) in
the two species under study. The picture shows the hooks of the last larval
stage (i.e. the L3). If it can be of any help for your project, be my guest.
Results and statistical analysis
Will be sent to you shortly (eh, you have to carry-out the experiments
firsts!) but you can start straightaway to study the scientific literature on
Wolbachia-host relationships (especially in drosophilids), you can start to
write your Material & Methods, you can start to sketch ideas for your
Introduction, you can start to think about the kind of figures and tables you
will use, there is a lot of work to be done before you get the results!
--- Good Work ! ---
D. Poinsot
The very mysterious case of the Ouessant fly
31
`