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Lecture 10

Lecture 10

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Biological Sciences
Rudy Boonstra

LECTURE 10 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 dont 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 varietiesmorphs 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 Hudsons 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. BGYC58H3F.November,20,, 2007 LECTURE 10 1 www.notesolution.comIn 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 wasnt correlated to changes in precipitation. Figure #3: you see two different scenarios 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 doesnt 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 animalplant 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 (potentially). 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 dont know. We have this accordion going on with regards to glaciation so we dont know the answer to that. It isnt like animalsplants 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 BGYC58H3F.November,20,, 2007 LECTURE 10 2
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