Even in Canada there is genetic diversity within species. This applies to bear populations as well
where there is a golden coloured bear. You might consider a pre-adaptation instead of a genetic
diversity that may have lead to the polar bear. If just looking at the species they all look the
same so they are species. They would enter the biodiversity as 1 number. Nobody knows how
to quantify properly and it gets very peculiar when you get to bacteria. It is more complicated
than the Great Barrier Reef that we talked about last time.
Relationship between how large organisms they can become and what they are eating. Eat a lot
= getting larger.
The size of pumas and their prey: the amount of energy from the trophic chain. Small pumas
of tropical regions prey on relatively small animals. More massive pumas of temperate and
boreal regions take large prey. There is this truism about the more you eat the larger you will be
and that is true. If there is an average of large bald eagles and in another area there is an average
of smaller bald eagles they can categorize the amount of food in relation to the prey.
There is a north-south gradient to this as well. This is a polar bear and they are by far the largest
bears on the planet in terms of biomass. They feast on prey that is larger as well. Queen Latiffa
narrates a movie about a polar bear and it is a very good movie to watch. The polar bear crashes
through the ice and catches the seal with no problem. There is a mention about polar bears
heading towards extinction and the numbers don’t support this. The population sizes of polar
bears have not reliably shrunk at this time. They are healthier now than 10 years but that may
not be true 50 years from now.
S: They are doing fine in the global warming issue.
P: They are not falling on to the line they can draw in the change in temperature. A professor
from here, Bill Goff, put out a paper about this a few years ago.
“Into the Wild” is a great movie so see it if you can. It is about a guy who gives up everything
and goes up to Alaska. He doesn’t last long and different things happen to him. In the movie he
dies of eating a plant that was poisonous and it killed him but that was just for the movie. By the
time he wanted to go home he couldn’t cross back over the river. I tell you this so you know
what to hunt and what not to hunt if you are in the wild. He spent so much time hunting little
things and by the time he caught them and ate them he got less energy out of the meal than what
he had spent getting it. In Alaska you have to put on the pounds to survive and that is why I put
it up here on the overhead.
The size of the polar bear follows a rule called “Bergman’s rule”. He was an ecologist that was
the 1st to relate body size not onto to what they ate but the climate in which they were living. If
you are a warm blooded animal i.e. polar bear it behoves you to be larger. The less surface area
you have in relation to your body mass. As you eat and get fatter your volume increases in 3
dimensions whereas the surface area only increases in 2 dimensions. Volume gain outruns the
surface area gain. This way the internal organs inside (heart, liver, pancreas, lung, etc.) are all
protected in the core temperature maintenance.
BGYC61H3F.October.27.2008 Lecture 7 2