from the howard hughes medical institute
the two thousand five holiday lectures
on science
this year's lectures evolution
constant change and common threads
will be given by doctor shaundy carol
howard hughes medical institute
investigator at the university of
wisconsin madison
and doctor david m kingsley
howard hughes medical institute
investigator at stanford university
school of medicine
the second lectured is titled
selection inaction
and now to introduce our program
the vice president for grants and
special programs about how we choose
medical institute
dr peterborough on
welcome back
tattoo howard hughes medical institute
out for our thirteen th
holiday lectures in science
now over the years we've
created we've had a whole series of very
interesting lectures but we've created a
lot of other our resources that go along
with those
put all of that material the lectures
animations virtual labs and so on
on a special website cobb bio
interactive that for work
and i see i encourage you to
to go over to that website at some point
and see what else is their bio
interactive dot org
our next speaker in the series
is doctor david kingsley and a change in
my investigator from stanford university
uh... david is well-known died in the
scientific community for developing
molecular tools
to study natural populations of steckel
back fish
but before he our talks about
sort of formal
natural selection david is going to
first talk about selection as artificial
selection
uh... for
a number of organisms this including for
example
the dark
uh... so here it is that they sharks
videotape you do st
i wasn't in lots of things i was in
early school
i had love dinosaurs as a kid
most kids are fascinated by
big bodies an interesting structure
windsor small from that time off
fascinated by
shape and uh... straight morphology and
and vertebrate
right now my whole ever comes scold
we've used a variety of organisms to
look at them
about seven or eight years ago we got
very interested in trying to use
the same genetic techniques have been so
successful in studying lots of other for
a problem
the study really hurtful
which is for genetic basis of for
evolution
we ended up
uh... hands down
of the small fish for the peace plans to
go back which is on the ground
spectacular uh... evolutionary relations
on earth
plotted
uh... populations can be found
here in california
that makes possible
go fishing
nearby
collect organisms that are undergone
incredible morphological change in the
last ten thousand years
bring them in the laboratory and
actually
look at it
the genetic basis of what has made them
uh... what different
a lot of people think that was just a
sort of his curiosity uh... gods
doesn't science
and it's much more than a lot of on
current medicine is based on what we
know about it for them
making armchair everytime
you're treated with antibiotics because
you have a picture of infections
the of position and you facing
and evolutionary arms race between the
bacteria that in your system
a drug that's killing the bacteria
and the factory is are attempt
to evolve
are to avoid the drug that's killing on
killing both for the picture
i hope that by the end of the holiday
lectures uh... people will have a new
appreciation for both
the diversity of living thing
but at the same time
the common origins
of uh... publicly
evolution views all around us evolution
and here's what his generated the food
service
text that we can
strategies for treating um... infectious
disease parking in the hospital it isn't
just
the historical process that's something
um... said continues all around us today
and in the most relevant ways possible
welcome back everybody
punchline
give me a great introduction to boast
charles darwin in the idea of natural
selection
darwin originally coined the term on
natural selection by analogy onto a
process of artificial selection
well-known uh... complex human breeders
human breeders i'd take metro variance
occur all the time choose are traits
that they are particularly interested in
breed selectively
from the plants or animals that show
those traits
and by doing so developed by a new breed
stick can look very different are from
from the original animals
darwin and wallace realized that are
very similar process what happened in
nature
so wild plants and animals period
and all sorts of randomized
but animals and many more are produced
than can possibly be producers survive
so inevitably are more offspring will be
generated from those random variants
that are the best adapted the particular
environment
as china poseidon virumail conditions on
your change all the time
and so animals
uh... are constantly being selected for
those that do the best in changing
virumail conditions
and are in wallace propose that would
produce
major changes in nature of justice and
humans have done an artificial selection
people i think are always surprised and
just how much plants and animals can be
changed by the simple process
of selecting operand them variants that
occurred
so i think it's worth i going through a
couple of examples
as it is true that of the products of
selection are all around us
selection has generated what we eat
uh... the kind pets that we keep
and i'll give one example today are from
the plant world and one example on from
the animal world
so what start out with corn
records a great example it's one of the
major agricultural crops are in the u_s_
major food source for both of our people
animals around the world
so there's words for cdot dot corn maze
in on every language around the world
cornice planted
on every continent of the world except
for antarctica
and despite that widespread distribution
yet all arose from domestication events
that have occurred originally in north
america
that summarized in the next video
so although now widely planted around
the world court was originally developed
as a local agricultural crop by native
americans in mexico
these people are harvesting corn
that was the paul stocks
the larger here's the growing completes
often
heidi cheer has hundreds of colonel
corners originally developed by these
people's ancestors who recognized the
potential of a wild plant to give rise
to a useful agricultural crop
interestingly that while plant to sent
today
looks very different
from modern corn
sow the seeds look completely different
the overall architecture the plant also
looks quite different
why don't you sent it has a bushy like
appearance
corn grows in these polls stocks
so very dramatic alterations uh... in
the architecture the plant really all of
its features
bush your call
uh... and good seats as well
let's look in greater detail at the
scene structure in this wild ancestor on
tsn k
so this on while plant is needed to
uh... balance in mexico and central
america
its seeds are shown here
actually just has a few seats so
typically approving body to sent a might
have fiber twelve
are kernels
that are completely in case
in estonia fruitcakes of that shown
there as the brown structures on the
left
interest sent a those are stoney creek
cases actually break off into individual
seeds that can be swallowed by the
animals and
uh... passed through the digestive tract
to spread the seats
ancient breeders selected for major
changes in ice even cover more quality
in the course of turning that original
arts tony for cases
into what seemed today in maine
so essentially what the uh...
integrators had to do
turned the original stony for cases
inside out
to reveal above the corn kernels sot
inside which are displayed on the
surface of the corn uh... corn cob
the stoney creek cases also softened and
turned into the interior of the corn cob
instead of the heart of the howard part
of her case
similarly major changes in overall
branch in architecture city of santa is
a wide bushy plant
corn is a poll plant
uh... years of the corner supported on
the central stock
in the paul plant makes it possible to
pack and lots and lots of corn stalks i
win
by your painting agricultural field
so how did a generic ultracet she by
these major transformations
well there's an archaeological record
of corn
so you see the first evidence of sort of
corn like maze carne asada appearing
maybe six two thousand nine thousand
years ago
was can actually uh... be dated the
earliest light-water in castle in mexico
near the sites
uh... where loyalty is sent a grows
that's one form of archaeology there's
another type that can be done this a
genetic archaeology
peso unit attempt to try to identify the
key genetic events that are responsible
for the major differences between tsn
cayenne corn you can actually today
setup crosses
between the original wild ancestor in
today's a highly director riveted
the plants are still so closely related
to each other that you can generate
fertile f_-one hybrids
and in the next few slides
tsn tick chromosomes will be shown in
red
maize chromosomes will be shown in blue
she crossed these two different plants
in in the first generation the f_-one
are hybrids
you'll have one of his sentiment maize
chromosome for uh... every crumb some in
the plan
if u in ur prostores art f_-one hybrids
to generate a grandchild or second
generation and after generation
you'll start to put together different
chromosome combinations
based on uh...
uh... memos lost
we all know from your genetics class is
for uh... simple man dealing in trade
you aren't typically will take from the
hybrids are randomly either the tsn pair
at the maze chromosomes or red tie perot
blue type in the our seats in the pollen
of each hybrid
we put them back together uh... during
fertilization to generate of that to our
grandchildren that are shown in the
squares
a quarter
of the offspring
were randomly inherit ought to
tsn taillight chromosomes
another quarter of the offspring will
inherit uh... to maze like chromosome
so in this grant i a generation you're
generating
uh... it different combinations the
bring back together some of the
chromosomes of the originals or are
still a mixture of
armies into something like like
chromosomes
piso that principle can be used to try
to roughly estimate the number of
genetic factors that underlie the major
architectural differences are between
mason tsn tech
in the simplest possible world of all of
the differences between a_z_t_
essentially we're due to a simple man
doing gene
you'd expect when you get one of these
crosses that twenty five percent
of the uh... f to the grandchildren
plants
would look like either the maze of the
case and take care
say it turned out it's not that simple
uh... so what would happen if the
differences were controlled by two d so
you have to have
two different genes on different
chromosomes together to produce the
differences
well then instead of seeing maze accuse
sent in a quarter of the offspring you'd
see them and one quarter by one quarter
uh... or one-sixteenth of the offspring
that's the chance of getting to maze
like chromosomes adi number one in two
main sly chromosomes achieve number two
for example
three genes it gets even worse the
quarterback quarterback quarters one
sixty four fourteen sits up
major conclusion from these kinds of
tables
if the genetic differences between forms
are controlled by a large number of
genes
it's very difficult
all of the chromosomes back together in
the right combination to regenerate the
print traits when you do this sort about
genetic crossing
jude and the one in allison's if the
traitor control
uh... by by a lots of genes
conversely a traitor controlled by
relatively few jeans
than your regenerate generate of print
like here types in substantial fraction
of the offspring as many as twenty five
percent for supplement and character
that george beetle actually carried out
a very large our cross of this are tight
you raised fifty thousand f two
grandchildren from a cross between may
cynthia center
what he found was about one five
hundredth of the plants
look like
the main cities and take care
and that suggests something on the order
between four and five genes that might
be involved in controlling of those
dramatic differences in plant
architecture and and and seeds
what are these genes
well geneticist can outdo lots more than
just calculate ratios impacts of his the
cated genetic maps have been developed
for all of the chromosomes five inmates
you can do these sorts of crosses and
isolate d_n_a_ samples from uh... each
of the art but have to france
major all the traits in the plants and
then type those d_n_a_ samples with
molecular markers that make it possible
to monitor
whether a given plant inherited tsn pay
like hermes like
uh... ha chromosomes for any marker that
you know
when you do that what you find is that
their particular chromosomes regions the
control particular aspects of our plant
morphology so there's a chromosome
region the controls
flowering one for branch pattern open
seats
uh... these parchment can simple man
doing traits in fact out there is
usually a major gene nichols a lot of a
difference in uh... afew minor jeans
but it's now also possible when you've
map the major factor that goes to a
particular chromosome region
to reach into that chromosome region
sequence the d_n_a_
uh... found in an area that's
controlling the given trade
identify all of the genes in that region
and try to find a particular candidate
genes
that may actually be are controlling
differences
the conclusion from a bunch of experince
of that tight
is that single genes make major changes
in the course of are generating the key
traits the record and mays domestication
for example
mutations in a single gene called she
has sent a branched one
can take a single linear like corn stock
and produce are more bushy plant that
looks i'd like to send pic
conversely there's a second jean-claude
t_j_ one that plays a key role in seed
and fruit case uh... morphology
if you introduced the maze version of
the t_j_ one gene into tsn tape
those stony fruit cases
begin to open up
soften up you get rid of the stone
covering and you begin to turn the
kernels inside-out in exactly the way
uh... the breeders son needed to do
uh... they exposed to all the kernels on
and your point
okay so i think that's a great example
of hal by i selecting
uh... for genetic alterations you can
completely transform
uh... the architectural plant
how about the animals
and uh... on for this example of
artificial selection i'd like to are
talk about dogs which i think you're a
wonderful example under introduced in
the next or short video
dogs they re all sorts of interesting
traits colors care textures sizes
behaviors that are interesting and
useful to humans
d_n_a_ studies suggest that all with the
combined all breeds are are derived from
walls
walls of lived near humans for thousands
of years
never earliest
archaeological evidence
of domesticated art forms of walls are
dogs is found about ten thousand years
ago in human settlements
at that time the skeletons of
domesticated dogs look fairly uniform
and some of the walls
by the time of the egyptians you can see
the specialized breeds being developed
that have long wins and one muscles that
uh... read actually still lives today
ending to recall the saluti
other breeds of in developer hunchine
retrieving
herding animals
pointers and retrievers and sheep dogs
are great examples of taking
ancestral on attracting men
hunting behaviors that were present in
walls and turn them in the selected
behaviors that are useful for him
so how is it possible to take an
ancestral animal and turn it into this
broad diversity of different allforms
but actually our listen
to a couple of human dog breeders
described
how they look
an animal and how they decide what it is
they want to do
i think that his mac is such a little
bit
too short he's got great strength in the
neck
but i'd like to have a just a smidgen
longer
uh... high also would like to have a
little more muscle definition in the
rear we could meet in chile the ability
to take fifteen
and use it like
paints
it's it's our are this is my car
i need this beautiful dog
and i'm chilling i'd meet her
right shows are cyrofin campsites for
several generations to make this
beautiful dot i'm very proud of her
okay so i think
that is a great description of what bob
readers do
they choose
damn cease-fire
do so for multiple generations they
picked race that they're interested in
in the developing animals that look
different to match artwork what they're
interested
so that process
extended by lots of breeders over a lots
of time has generated
an incredible diversity of are different
dog breeds that are shown roger on the
slide
we also have a couple of skeletons from
different dog breeds hot
here on the stage
this is actually the skeleton of a
german shepherd
misses the skeleton of a boston terrier
see all sorts of uh... dramatic scalable
differences are between the two dog
forms
the most obvious is maybe the the much
longer went to the waves here in the
german shepherd and are banned in the
terrier
also dramatic changes are in the jaws
soda muzzle of the uh... a german
shepherd is much longer than the short
muzzle of the boston terrier
he come at the break you can actually
are capped teeth
there's more molars art in the german
shepherd then found here
like the vertebra column also differs
there's twice as many vertebrae in the
tail
of the german shepherd as found out here
in the boston terrier
to darwin pointed out that if the
paleontologists found the skeletons
he would definitely naman different
species because of the dramatic changes
and yet these are examples of dramatic
transformations
that have been achieved about human
acumen breeders
so what's actually happened to transform
on all of these different skeletal
structures
exactly the same sort of genetic
approaches can be used to study this
problem as we introduced for the corn on
q sent a problem
so in some very interesting our genetic
experiments have been done trying to
look at the genetic basis of uh...
producing scalable differences
well my favorite how forms of the six
burma cuz it was one of the largest i
was done in the nineteen twenties and
thirties
by a man named charles stockard
stockard got a big grant out from the
rockefeller foundation
and use that not to buy a farm in
upstate new york
so he called this the cornell anatomy
farming for about a dozen years he got
in are all sorts of different dog breeds
and carried out interesting crosses
to try to look at the genetic basis
of forming behavior in docs
let's look at some of these crosses
sick ross that on stockard setup between
the german are shepherd and the basset
hound
in the german shepard has long waits on
basset hounds have short legs
the f_-one hybrids of this cross also
have short legs
that suggests there may be a dominant
factor in the bassett breed that causes
short leg length
few inner prostate f lions and make the
f two are grandchild generation
dogs come out with a mixture of either
short
work whole eggs
and even into a small numbers of animals
on the regenerated here in the dog
letters you can see
that short and long legs occurring
almost a min deleon three-to-one ratio
get a dominant trait so only a quarter
of the offspring show the short legs
birth those long legs their
characteristic of the german shepherd
parent
so these sorts of results are consistent
with a single men doing in gene
by the controls the difference in
labeling of between these dog breeds
here's another cross
this was set up between of the boston
terrier and the docs and the weiner dog
you cross these two animals the f_-one
hybrid again what's intermediate
looks a little more like i mean the docs
and in the boston terrier
pm across the uk ones
but the chromosomes so together in
different combinations you could very
interesting sorts of f two dogs coming
home
so this in one right they would have to
miss
it has the time the blaze of the boston
terrier
it has it years
that are the size and shape of the docks
in
but they're held in the upright position
of the boston terrier
pain out so that are a suggest different
genes controlling here shaping year
elevation
but remember something else from the
table dot we went for through before for
corn fierce gunfight
if the traits were controlled by very
large numbers of genes it's almost
impossible to get back in a small number
of animals you need that will show the
chromosome types in the traits of the
original parents
what's seen here is a very small numbers
of animal should getting back to have to
his
who's here shape looks like the docs and
includes your elevation looks like the
boston terrier
again that suggest relatively few
genetic factors are controlling those
different rates
okay one last crossed
this was one of the more dramatic ones
on the cornell amanda reform
was set up between the saluti
so the salute he is that along muscle on
limb dog out that we showed earlier in
the egyptian photo
this is actually the skull of us lewke
dog you can see that it has a very long
muzzle
much longer than is present argument
pecanins
which of course a very short dark
very squashed in face almost no muscle
it all in very short legs
this was all one of the hardest crosses
that was tried on the cornell anatomy
farm
again he was able to generate uh... few
f_-one hybrids they work in a media com
patrice to parents
sophie in across the appointments
you get some very instant have two dogs
come out
turns out that the length of the upper
to lower jaw is inherited independently
in the cross
so some of the dogs
come out with floor jaws that are longer
than the upper johnson
some of the dogs have good match between
the up in the lower jaw and in this dog
in the lower right has the opposite
problem
it's opportunist so much longer than
floor jar that it has uh... constantly
opportune time
again those are very much like that your
results it's clear that there must be
different genes for different our trade
so opportunities and lowered on teens
are different
but it's also clear that you can get
shorts and longs coming out in a very
small number of uh... f two animals
which you can suggest for a given bone
but the number of genes involved are
likely to be small
peso a summary than of a lot of
different hotdog genetics of genetics of
individual traits
can be relatively simple
simple man doing gene for labeling for
example
relatively small our numbers of genes
like the controlling some of the other
differences
at the same time different genes
controlling the growth of different
bombs
and i think it's that combination of
factors that makes it possible
for breeders to do what they do
there's different genes acting in
different body parts they have major
affects morphology you can pick a body
part that you want a modified
choose our choose variants that occur
and selectively breed from those in
order to generate
uh... dramatically different forms
so for both to sent in for dogs a
selective breeding can generate
of very large changes in a short amount
of time
what's out there and i'll be happy to
take questions
very late in nineteen eighty eight
revision everythign sale finds in his
face is just
morris as israel's new jersey businesses
features
so the question is how much uh...
molecular genetics guide screen outdoor
breeding i think that the breeders that
i you saw interviewed here
weren't using results from d_n_a_ to try
to decide that particular gammons fired
that they were are that they were going
to choose for the next generation
you could do that now so they're on in
an organized program if you want to try
to speed the process
you could use molecular markers to try
to screen progeny for those that might
park area crumbs on a particular
interest
but historically it's all been done
based on just looking at animals and
choosing
fina typically the ones
that have a little more muscle
definition in the rear
or are polar bears are shorter here's
what's up
pages
god's house
do you think apparently never
lynch
is there any usually veggies too
there never was tending to be able to
choose a hunting she
different bones differently
i think the question for uh... jaws
is an interesting one because
you're worried about the mismatch uh...
between the teeth on the upper jaw and
the lower jaw and you would think that
normally those two traits avoid would go
together
what it looks like if you look at the
amazing variations and bones in patterns
that vertebrates are able to achieve
they achieve that because they have a
modular genetic control over what's
happening in mutual bum on throughout
the skeleton
and that makes it possible to tweak and
change curtain shin bone into all kinds
of useful adaptations for running and
copy in swimming and falling into enemy
are running faster it's federer
you have to be able to encode those
differences somehow in the genome so
it's done by a very scattered genetic
system
with selection deciding that's a fic
combination or that cific combination
and other by produced in the overall
forms that are seen here
tsn
there
leading did
there anything
accidentally danielle
lassie's
back to me that he hasn't
right so again cha got several questions
too about whether the mutations in the
variations
know what they're gonna have to be calm
they don't
so the variation occurs at random and
all different directions it's really on
either artificial selection by humans or
natural selection looking for fit their
units that the sides out of all of the
random variations that occurred
this one
uh... is a feature that its human
breeder would like or this is one that
has survived better
left more offspring may only be a small
survival difference five or ten percent
is lust ron mentioned
random variation
and then choosing
based on appearance for based on fitness
is what generates the different on
breeds
and or stocks naturally and then died in
modern day times
people are hard at work trying to
improve corniel's using
uh... all sorts of genetic techniques
including on breeding monitoring
chromosomes
and sometimes now inserting genes that
might improve resistance to
uh... to tests that are consumed the
crops uh... etcetera
so they did the modifications we see
today are mixed reveled in the
techniques
but the old techniques have already been
able to achieve
are remarkable things
you think that uh...
delusions jeans movies leads but nothing
on undo any problems arise and brutal on
civil war removing with jeans
rights that's a great question are about
whether
the kind of mismatches that can
sometimes come up in these uh...
different dog breeds aren't create our
problems
that actually aren't is true that there
are dog breeds that now have such
uh... morphological extremes
that alive for weren't for humans
helping them along on either with food
or father some dog breeds that now are
uh... usually delivered by caesarean
section because of the mismatch between
the offspring and the birth canal of
uh... of the parents for example
it is true that um...
artificial breeds
are sometimes selected for traits
uh... that would reduce
their over all of my ability
to actually is a great transition
into what we're gonna talk about uh...
in the next section so i think about
uh... thanks for all the questions and
will will start the next section because
in the next section
we're gonna talk about
selection
under all four range of fitness
constraints in the white house
okay so
in nature
there isn't a human error helping you
along about to be born earned two sir
you a particular kind of food you really
have to be a fit and more fat than
anybody else in order to attend survived
survive and adapt
and that brings us back to darwin's ke
analogy
uh... he knew that artificial breeders
have been able to achieve
major changes harkin body form
uh... by uh... by selective breeding
and he argued
natural species
would also
i'll be able to change in dramatic ways
in the natural selection would be able
to transform wild plants and animals
based on differences uh... in fitness
so for the rest of the talk i'd like to
on focus on evolution not inhuman corn
fields are in dog kennels but by
evolution subject to a full range of
fitness constraints national violence
and to introduce the organism that will
be talking about by have a
video
is actually on is an actual episode of
jeopardy that air depart two or three
weeks ago
double jeopardy
these are going to be fun
world capitals
fall about movies to the back
almost assassinated
american women
for
said there'd
finda
and articulate what it does
it may ring a bell but this capital of
billy's
also starts with belt the elf
john was doubled
belmont and that's right strikeout for
seven fifty four hundred place
the brown type of this power to bert
plunges from the air to fish
the white one scoops up fish as its wins
junk but not in right
here's what it does
the dorsal spines give this fishing here
its name
it is a staple
stable tactics chung
apec not gonna ask you guys
hotmail you would have known on the
pelican
i mean you would have known of the
capitol believes
is to get cancer
how are you would have known that
response nickelback
okay so let let's talk more about the
small fish that's uh... now-famous
enough to have actually made it on the
jeopardy
but on the other hand was the two
thousand rather than the four hundred
dollar question on jeopardy and was
obscure not that it's time to all of the
contestants even the ones who knew the
cap for please
they said this artistic a back to the
small fish on
incest or form is found emotions about
three inches long
steckel backs although they live in
oceans or like salmon so they migrate
intel freshwater our streams
every year to spawn
so these are allusion fisher constantly
mock
scene and probing a freshwater
environments along the coast
that lifestyle
has been key to enormous evolutionary
radiation of the fish that actually
uh...
plays upon one of the fact of the chon
mention the first lecture nesting norms
environmental changes that have occurred
at inverse over time
what shown in blue here are these huge
ice sheets are that used to cover north
america
uh... during the time of delivery ritter
pets on for example
ice age animals the trauma showing
so about
fifteen thousand years ago those large
ice sheet started to melt and that set
off on evolutionary radiation that's on
summarized
by in
than next environmental video
patient during the uh... i stage these
huge sheets are covering out lots of
land mass
ice was incredibly thick so my old my
alarm white thicknesses of ice piled on
top of land and then
or starts the war
so widespread melting of those ice
sheets on begins
and the glaciers
uh... recvd
leaving in their weight
environments that used to be completely
buried under ice
butter now exposed
if you go in the areas like for example
round british columbia you'll find that
the highlands around vancouver
are dotted
with fresh water post glacial lakes
covered by any means
formally ice-covered region
those freshwater lakes if you are lookin
them very frequently have circle back to
come in out from the ocean but then
adapted
for the local environmental conditions
and the like
adaptation includes our decisions about
out how to avoid predators
the shows a tryout trying to keep us to
go back
you can see this the correct sometimes i
get a waste of our armor that they have
can be very useful
fickle backs are also argued invite
insects
the crane strategy of an insect is
actually to reach out and grab on to
things like spines of stick a bass
army one million
and then come under some
uh... from the spot
so depending on the kinds of predators
that you're our encounter in different
ways
it may be better or worse not to have
more to lose uh... armor
that's just one example of the kinds of
environmental factors set off by this
widespread change the claimant
but then an adaptive radiation as men's
astro marine form on it
colonizers
and of walls to the ecological
conditions in different ways
the ancestral marine fish always shown
here
they're not usually this red this fish
is actually been stained with a bike all
the loser in red which uh...
headlights although the skeletal
structures
the marine fish
completely covered with armor plates
from head to tail
it has the three prominent spines that
alex kaback mentioned
you also see a spine down here on the
belly region that will come back to
that ancestral foreheads radiated
indifferent freshwater lakes and streams
throughout the northern hemisphere
europe and on north america and asia
when naturalist first came through the
lakes in the northern hemisphere they
found what they classify
has over forty different species of
steckel back because they look so
different from each other
so in these freshwater lakes
the three spines to go back to new turn
into a two spinal once binder and those
plans to go back
the teeth in the jaw answer extensively
modified as the fish adapt to different
food sources that are available in
particular environments
armor patterns change a lot
you can be heavily armored and slower
lightly armored in fast though kind one
of the fish comes and goes
colors uh... variety of physiological
traits salinity tolerance temperature
preference it all depends on what
environmental challenges
uh... the fishermen trying onto beach
all of this has happened
in just the last ten thousand years or
so since these environments got created
and in fact although many of the fishery
productively isolated in the wild the
ice lady mechanisms turn out to use
would be either behavioral or mechanical
incompatibilities
so you can overcome those by squeezing
out by a decent sperm off from the fish
and uh... you can are can raise
perfectly fertile f_-one hybrids they
can then be used for exactly the sort of
genetic experiment that we've gone
through before
for key is sent in corn
to try to track down the genetic basis
now
of evolutionary change in natural
population subject to a full range of
fitness constraints in a while
all kinds of interesting on traits that
are uh... analyze a bull by the sort of
approach and that's because of the
incredible diversity of different rates
that have evolved
uh... in wild steckel backs
sexually huge literature on stick a
backs a couple thousand papers and
several full length textbooks are that
have been are written
on the distribution in the ecology and
the morphology
and the behavior of different fish farms
around the world
so how it's possible to take almost any
trait that you're interested in and find
interesting is the correct populations
we in many others to go back labs i send
out
uh... students and post docs from the
lab each year it a coke liked from on
interesting sites were fissionable
this a graduate student lamp on shown
collecting stick a backs in the
northwest territories the fisher
relatively high easy to catch
you throw in these metal buckets that
have chronicle openings at the end
fish get funneled in onto the trapped in
the hole was small enough that
or they're not smart enough to swim back
out the other side
so if you trap a whole bunch of lakes in
strange in just come back the next day
in their traps aren't typically or cargo
obstacle back sanam
the fish are small and i'm relatively
easy to move around in our work within
different uh... aquatic environments
you can see here but it's a fish that
have all been brought back to a hotel
room uh... in the northwest territories
texted possible to set up ah...
fertilization sin crosses under the
microscope are right there in the hotel
rooms and bring back for my state
clutches
we also bring back like fish
raw silk lab rating with a lots of
steckel back investigators that are
interested in particular populations and
have studied them for years
including uh... long-standing club race
with dole splitter at those university
british columbia who raises thousands of
stick a backs every year
uh... for ecological studies
okay so we've got all sorts of different
rates that are uh... segregating in
these wild populations
want to talk about the genetic basis of
some of the difference is i will start
come by complain about the lateral
plates this is one of the major
morphological differences that's a bold
repeatedly in on different
different our locations
the sod images actually taken from an
old uh... monograph
by uh... a pinch french nationals could
be a who
several decades before the origin of
species gave different species names two
marine and fresh water forms of steckel
backs because of the dramatic changes
aachen banding patterns
reformers from the top with plates from
head to tail
fresh water for mission on the bottom
mini the freshwater forms have lost a
lot of the armor plates
uh... retain them only at the front or
having very complex at all
again this is taught to be
uh... almost a military decision about
the best kind of armor to have in
particular environments you can either
be heavily armored and small
or lightly armored and fast so there's a
higher bursts wind speed in the located
steckel backs
depending on the predators that are
chasing you it may be better to have one
form of the other
you know we can do first to go back to
exactly the sort of genetic archaeology
experiment that we describe before for
mason kia sent it
so take a marine form
and a freshwater form that look very
different in the number of plates
thirty-five or thirty-six plates in the
marine fish on the left
only a single plate left on one of these
freshwater populations from uh... paxton
lake near vancouver
generated f_-one hybrid generation
inter proce
the f_ once the generator you have two
grandchildren letter i'm putting back
together in various chromosome
combinations all of the marine in the
freshwater chromosomes
then go in
count armor plate numbers in all of
those i have two offspring isolate
d_n_a_ samples play problem with a set
of genetic markers that we've developed
for genome-wide linkage mapping in stick
a backs
and then look to see whether there's
particular chromosomes that always go
together up with particular tricks
when you do that what we found
was that there is a single major gene on
the distal end
of uh... leakage group four
that controls about seventy percent of
the variation armor plate number on in
the cross
so uh... very large genetic defect
sana symbolism in doing in trade
there's also are chromosomes that have
smaller quantitative affect some plate
number
three call these modifier genes
quantitative modifiers
they may teach control summer between
five and ten percent of the variation in
armor plate number
uh... in the cross
hit so many ways is results very similar
to what i described before
uh... for doing this kind of experiment
inmates are key isn't it
as a nation to sent it's also possible
once you've identified one of these
chromosome regions third go into that
region
sequence all of the d_n_a_ in that area
and decode
uh... the actual genes that are in that
region that may be controlling out the
traits
we've been able to do that before this
major jean region the controls armor
plate number instead go banks
and been able to identify a single
signaling molecule gene
that plays a key role in armor plate
formation
the easiest way to demonstrate that it
plays a key role
is to reintroduce that gene into
eggs from low armored fish
so you can aren't directly inject
fertilized eggs from law armored fish or
with the gene from the chromosome region
the controls armor and when you do that
you put armor plates back on the side
statistical back
again very like the kinds of single gene
experiments that have been done
uh... for corn deus intake
my conclusions are very similar
single genes can control uh... major
morphological differences
now in these populations that have
evolved in that room by him
kato's actually i don't talk about uh...
one other trade which is the presence of
the absence of the hind fitting
fica like most land animals they have
four major coffins
uh... and it is our limbs
to uh... four friends or pectoral fins
and too high a fence
or pelvic fins
these are treated modified in some of
the fish populations
we think that that presence for the
absence of the huntington is actually
very interesting sort of trade
because as the same kind of trade that's
evolved repeatedly in a whole range of
different animals
first takes and some reptiles are
have evolved major when reduction
they've lost both the forms in hind
limbs
whales and on some aquatic mammals like
on
manatees
have opal
hind limb reduction they still retain
four friends or flippers but they've
lost on the plane thin
and pelvic her hind ten reduction also
occurs both in fossil steckel backs and
bought him some living populations
again in those special populations that
have decided to lose their hien phan
spot to be are unlikely adaptation onto
particular predator environments if
you're a fish that's evolving
environment where there are two new
truck trying teach you so you don't need
the artur rec spine to try to avoid a
trout
but you are being not chased by insects
that may actually be good to lose some
of these are structures
uh... that uh... predators try to grab
onto
so i'll show you are a little bit higher
resolution look at the hunt for the
mystical back continent the short video
this is a tree dimensional
reconstruction of the stick a black
skeleton on created by craig miller in
my lab based on our uh... micro on
x_-ray approach
meeting armor plates that we talked
about before along the sides of this
marine fish
then colored in red you can see the
public apparatus
which consists of this pouring the
projects from the site of the animal
audit articulating a ball and socket
joint with this underlying public
structure which children read wrapping
around the side and on the bench will
surface for the fish
the fish can actually raise and lower
those fines are that's so they're not
vote public and consists of the sparring
and sunderland our public bomb
marine fish
always have the pelvis the forms front
the top felt was highlighted in red in
the middle
but again some of the freshwater
populations
i have evolved the complete elimination
uh... of the hun sen
like the paxton like instrument the bomb
so what is the genetic basis of
completely losing eleven
uh... in natural populations
again we can use exactly the same sort
of genetic archaeology approach
measuring now on the presence of the
absence of the hind families crosses
between marine in freshwater fish
when you do that it turns out
we get a result that should be on their
sounding familiar
the single major gene that maps to the
distal end this kind of like a troop
seven
that controls
about two-thirds of the variation in
public size in
the f two progeny from the sort of cross
once again
it's not armin dealing in
so there are series of chromosomes that
have smaller quantitative affection
control maybe five to ten percent of the
delegation
uh... in public sites
so again
more complicated then mendel
but even the presence or absence of an
entire uh... lemur fan here is being
controlled by a relatively simple on
genetic system
just as we saw before
for major transformations
uh... in both horn
and and dot
so i think it is amazing what can be
done by simply
selecting an accumulating clyde genetic
variance
artificial selection has transformed to
sent into mason transformed our walls
into a diversity of different dog breeds
but natural selection can generate
equally large changes incompletely wild
animals
that are adapting to the kind of
environmental changes that occur all the
time in the history of the earth
one of the conclusions of the sort of
uh... genetic work is that it doesn't
take that long to generate are really
major changes in plants and animals
so all the changes that we talked about
have been generated
uh... in the last ten thousand years or
so
that's just a blink of the i compared to
the long geologically resisted on chon
summarized in in in the first
so how r can things go so fast
part of the answer is that single genes
have bigger facts
right so we saw that
fourth are the genes that control the
fruit cases in coorg for the branching
pattern
important
for the late blank
uh... in dogs
those are all examples of artificial
selection
sako same thing we've seen on some of
the genetic analysis of
natural selection
so major genes that control armor plate
numbers or our presence or absence of a
friend fan
or in the case the charm mention this
morning
uh... whether you're a black her light
colored are rock pocket maps another
example metro berry ation
the other thing that helps the speeding
is it doesn't take very long for
selective pressures to increase the
frequency of an end and advantageous
allyl once the mutations occur even at
random
sean showed you this morning that that's
true for the case of coke colors in
pocket mice
one percent five percent selective
advantage and pretty soon
whatever the gene is the controls that
trait spreads rapidly out through the
population
that's likely to be true not just for co
colors but for a whole range of
different rates
think one of the striking things about
the stucco backs
is that all sorts of things have changed
in the last ten thousand years
skeletal traits
feeding traits
treat related to meeting in reproduction
and whether fishery even compatible up
to meet with each other
all sorts of physiological differences
in behavioral differences
that the principles that shana outline
this morning how one gene could sweep to
produce a color change uh... in five
thousand years last
is actually an example of selection
that's occurring
for multiple traits
simultaneously
even a natural fireman's
there's all kind of challenges out there
uh... in the changing world
in the process
of random variation followed by
selection for those very insular best
adapted to a given environment
can do remarkable things to take animals
and in a time scale
that's completely compatible with the
needs of the animals onto are adapt to
different violence
so i'll stop there and i'd be happy to
have to pick up more questions
yeah kasi anyway so yeah
waiting to hear values yet
well when he got to be but we have two
guests
decides that is the message services
anymore and it is and what they do you
think it is not involved in the world
has to do that environment
or how it worked great question what
would happen if the dollar rate for
release from the wild
miss actually i a m
fishing question because one of the old
arguments about whether artificial
selection was relevant to the way i wish
they would work as a lot of people so if
you release those dogs in the wild
you don't think he talks right i mean
the high and
therefore the kinds of genetic
architectures that underlying
the major changes that humans have been
able to achieve
aren't relevant
for the kinds of genetic mechanisms that
might underline
a process of natural selection to change
the environment
i think that's one of the things that's
so striking about to stick aback
resolved
there's no humans and ball in trying
fiscal these organisms to adapt to these
new post glacial lake
and yet if you go in and use exactly the
same sort of genetic archaeology methods
to try to investigate
what kinds of genetic changes and rely
doug's differences
fact the architecture's
are many ways surprisingly similar you
can get major genes
uh... have
uh... substantial affects on huge uh...
huge structures
and uh... i think that
uh... that shows the power
of what genes can do and the power of
what selection can do by acted on the
jeans
visit hostels only de casa aslan crosses
lately sleazy dogs that he's innocent
accident
uh... victims also decide if i didn't
read tributes to leave the seen the
children from the same hands
you
questioned whether you get in reading
the factory duties were to process and
you can't so
there are uh... recessive mutations that
can be present in population this
concept mutations occur randomly
so during the replication d_n_a_ you'll
get heiress
those are sometimes are
are not apparent in less are the jeans
the same a mutation is on both
chromosomes so they may have occurred
original one but when you start to in
brief you bring those on the patients
together sat absolutely are can be seen
uh... inbreeding um...
inbreeding effects that uh... that
plague played breeders because you have
to find the stuff that you want to mix
the stuff that on bet
that you might not want
i think what that really serves to
emphasize is something that came up also
in the questions this morning
the process of mutation itself is random
it's not that uh... corn for that you
sent a new art form should look like or
that the dog breeders
were able to pic
pre-existing aren't traits that already
buried in the way that that
somebody wanted to have happened
mutations occur at random they can be
advantageous they can be disadvantageous
what selection does is it screams
the ones are that are bad are eliminated
the ones that are good can be chosen
either by a human breeder
or by the process of imitation having a
wonderful over ten percent advantage in
overall survival or on or reproduction
i'll take one dollar in the rate in the
red shirt
steam matthew michigan q_c_ eight
sixteen planning d thank you and he's
been offline contact romance
negligent in the areas that have entry
now twelve citizens and and and i'm so
there is no more experiments have been
going on to look at the genetic basis of
are
domestication traits and other animals
implants
so part of the motivation that research
is if we understood the jeans
made crops better for humans it might
actually be possible to move the
teachings around in a more designed
target approach improve plant
very some more work that's going on for
tomatoes to try to identify the genes
that make me there was no big big juicy
uh... there is some more work that's
going on in the car lots of different
organisms
so far
i don't know of any examples where one
of the domestication genes that has been
found in on this plant has been moved
over into another one
but i do think that the better our
understanding is of how you can change
plant architecture the better long-term
hope there is
operate cheating real improvements that
are based on trying to modify our
knowledge of the genetic pathways of how
the structures develop
off by a lot
i gather from here
moving video that your laboratory
similar ideas positions in the uh...
database
do you do this
but just to read
board through
musicians
for the that's the correct product in
lab is very focused on trying to analyze
the genetic basis of natural variants
had never been manipulated and humans
so lots of people work on mom organisms
may sit up needed genesis experiments to
try to identify
are rare very instead
uh... test
what it's possible to do to an animal in
the laboratory
mystical back project is very geared
toward trying to understand how nature
has redesigned the animals and natural
environments
so all of the crosses are
taking wild caught fish that have
adapted in different areas and then
trying to
carry out these sorts of experiments to
identify what genes that made them are
not the way that they do
okay i think we could take one last
question now
mistreat
he thought
pieces
they still exists
so i'm
by the one the most remarkable
demonstrations of how close related dogs
and wolves actually still are is the
fact that you can breathe walls and dogs
still make our fertile hybrids
the dog genome project i've just
recently i have been carried out we've
got a lot of sequence information now
from dogs and you can ask what other
organisms are the most closely related
to dogs based on d_n_a_ sequence that
confirms the same thing that on people
move from breeding experiments that
uh... dogs come are very closely related
to what you can see that both by the
inner fertility and from god similarity
in the in the sequence
you are the easiest possible day
okay so our thanks very much on we're
happy to take on more questions at the
break you'd asked great questions and
i'll give it back to p
gave it up
i'm really glad that we selected you to
give a lecture
it's really exciting i think to to learn
how our evolution is working in the
living populations now i had to see the
mechanisms behind it
there were always good questions and
there are many more and i know are
audience out there in the virtual world
i couldn't ask their questions anyway
but there is a way you can ask these
questions
that website i mentioned before bio
interactive dot org
has a section called ask a scientist you
can't
go to that section and put in a question
and our panel of volunteer scientists
will answer it for you not only will you
get an answer back
but if we think the question is
generally interesting in the answer is a
good one and then we'll put it on the
site for others to see and there's an
archive of questions and answers and a
search function sets actually a pretty
good resource and a lot of things so
have to ask a scientist
on up i'll interactive dot for
that was a commercial message
so join us again tomorrow out for two
more lectures on evolution from our
speakers
david will explore the connections
between fossil
evidence in the like your evidence
uh... for evolution and shana lmu our
revolutionary thinking from insect wings
to human traits
