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Lecture 10

Lecture 10

Biological Sciences
Course Code
Rudy Boonstra

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November 20, 2007
There will be a tutorial on Thursday.
I taped a video: John Magnasan gave a lecture and he lectures about fresh water and
global change. I watched the first 10 minutes and Brendan will present it. Watch what
he says and take notes. Some of the arguments he makes are very good. He is a good
scientist, highly specialized, and he will talk about what I am talking about today.
You have a paper to discuss as well.
Last day I talked about the implications of climate change and how the biological communities at
a whole range were being affected. I am just touching the surface of literature that is coming out
on this subject. There was a journal last week on animal ecology. There are thousands coming
out every year on this topic. Some directly look at plants and animals.
Evolutionary and Morphological Changes
I will get to that example in a minute. I will give another example right now. A fact usually
downplayed in the discussion of responses to global warming is the tendency for evolutionary
changes to occur. There is strong selection, if you don’t measure up you are gone and someone
else will take your place. Example: The white mouse of the lab world, (Latin name of insect)
that was typically found in Europe and in the Northern country you find individuals with longer
wings in the southern part they have shorter wings. We bring it to southern California but we
only release the short winged forms. Now if you take a gradation from B.C. to California you
see the same as what happened in Europe i.e. long wing in northern portion and shorter wings in
southern portion when we only released short winged forms. This means that the selection was
for different varieties/morphs to meet the different environments. The environment dictates what
the animal looks like and what ones can survive.
In the Pied Flycatcher as the temperatures warmed the eggs are getting bigger. It is a bird and it
sits at the end of branches and ambushes insects as they fly past. This is typical of a reasonable
number of birds i.e. barn swallows as well are getting bigger. Remember egg size is critical, the
larger the egg the larger the babies.
Polar bears in the southern Hudson’s Bay, look at the condition of the females is declining
because the length of the ice period is shortened. Ice leaves early in the spring and comes later in
the fall so they have to live on food stores and the babies will be in poor condition as well.
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In some butterfly and grasshopper species in Europe the wings are lengthening because of
moving north. Their reproductive output is decreasing so it is a trade-off. It varies by species.
(Refer to overhead) This is Neotoma cinerea which is a wood rat. It is our native rat. The other
name is ‘pack rat’ which means you hate to throw things away. Here you see the range of the
wood rat. What you find on the chart is the average body size and the temperature on the graph.
This is part of the thermal window of this particular native rat species. We have native rats here
and they are highly selected to live beside us. This one is a nice native rate in this overhead. I
worked in Jasper and we stayed in a warden station. We prevented people from coming in and
poaching. On the ceiling it looked like someone had urinated and they had. They live in the
attic. So with the wood rat as the temperature increases they get smaller (July & January) so this
tells you something fundamental. There is selection about large body size here and where it is
colder. There are biological reasons for this. As global change occurs you will see a change in
body size in this particular species. They could actually pinpoint a 2 -> 3 degrees rise in
temperature was the driver of body size and it wasn’t correlated to changes in precipitation.
Figure #3: you see two different scenario’s here. You can see fitness (# of babies that you have)
and at the top you have a stable or changing climate. The phenology during the stable period is
stable and the change is change. This is the optimistic scenario where fitness doesn’t change.
The full line is temperature and the dotted line is phenology i.e. wing length, body size, # of
babies, etc. So it is constant and it declines and the phenology of this optimistic species the
animal/plant compensates. As it does fitness remains constant. Just as good under change as
under stable. The alternative is that you see fitness trying to hold its own then you get outside
the thermal tolerances and things change. So temperature goes down and the phenology remains
constant. There may be no more genetic variation to allow them to compensate for the change
S:Is one theoretical and the other actual?
P:No. I will give an example though. What drives an animal or plant to extinction? This is
what you have. In all likelihood we don’t know. We have this accordion going on with regards
to glaciation so we don’t know the answer to that. It isn’t like animals/plants are adapted to
constancy either over the short term or long term. There are many genes that make a particular
trait i.e. body size.
Figure #4: this is a red squirrel and they are about 200 or 250 grams. Why do they have those
eye colours? This guy lives in the southern Yukon. If you take yourself back with respect to
temperature change, where will we feel it most dramatically in Canada? We will notice it in the
north. If I look at Whitehorse temperatures in January it is the same as Toronto quite often. If
you look at the average spring temperature over a period of about 31 years you see the
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temperature has increased by about 2C degrees. Secondly, if you look at precipitation there is no
change. Only temperature changed over the 31 years.
Figure #5: what does this mean for the female red squirrel? They eat the spruce cones and the
only way they get through the winter is by this food supply. You can see over a period that we
are documenting was that the spruce cone crop increased over this time, about the last 10 years
of this 31 year period. If you look at the parturition date (when they give birth) this is 110 or 115
days after January 1st and you can see the parturition date is dropping. They are giving birth
earlier and earlier as the temperature is increasing so they are compensating. The question is
why? What is driving this change?
Figure #6: 2hat a PhD student did, Andrew McAdam, was a huge amount of work to follow
them over multiple years and also followed the daughters to see when they had kids. You can
build a picture that requires long term monitoring. By doing this you can decompose by some
complex genetic equations (same as when you do breeding experiments in cows and chickens)
and the bottom line is the following; you can decompose the variation you can see amongst
females into 3 components. There is natural inherent variation called Phenotypic plasticity
which means she has the ability to vary the birthday between 15th of March and 15th of April.
Evolution is 13% and this amount of the variation is genetic. Natural selection can operate on
that and as the climate changes it can select for those who have an advantage, those who can
have babies earlier. 25% is unknown which means we don’t know what is going on. This is a
very critical study in the Yukon which was flattened by 3 Kms of ice in the border area because
of glaciation and deglaciation. These populations would have been pushed north and south.
This is all I want to say about the biological impacts in the world regarding climate change.
(Quote – Paul Crutzen (Nobel Laureate) & Will Steffen (International Geosphere-Biosphere,
(Quote – Sir Winston Churchill, 1936 – said in response to the growing menace of the Nazi
threat in Germany in the 1930’s)
Now I want to talk about one of the critical resources that is affected by climate change and that
is water. It is absolutely essential to life. We talked about temperature but what do we know
about water? We will talk about fresh water.
Total Global Saltwater and Freshwater Estimates
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