robust to insights but if you are a baby you can’t. If the environment isn’t suitable the adult will
survive and the baby will not. You have two zones, dark blue is optimal and light blue is marginal, so
if this is an area within the geographical range of the species then site A falls completely within the
temperature moisture gradient and so does B. For C and D a portion of the variation falls outside
their zone. So portions are suitable but not all the time so this is the extreme idea I mentioned.
This gives the niche space for this bird called the blue-grey gnatcatcher. They forge at different
heights but this shows the tolerance and the optimal height that they can eat. Why not go to the top of
the tree? There is competition and predators. Here we have Cooper’s Hawks and they will just pick
off the smaller birds.
This shows the Loblolly pine tree. The dash line shows the natural limits and this purple line is the
calculated limits. IN trying to project you have to understand how this pine species will respond in
the new environment that is coming.
The same thing goes for birds. Here you see the Eastern Phoebe and we have it here in the summer.
They catch flies by sitting on the end of a branch and waiting until they fly by to catch them. The
bold blue line marks the edge of the winter range. Isotherm is the zone of equal temperature across
The other thing to think about is the problem of ecotypes. Within a species there may be a number of
different races and each race is adapted to a unique environment. They may interbreed but they cope
with unique environmental conditions of a particular site. What might happen with climate change?
If you look at initial time and the geographical range of the species (blue -> green -> yellow -> red)
and each is an ecotype. You can’t assume that within a species everybody has the same genetic
compliment. They can do everything everywhere and this is very important. With climate change
species will have to move and have to move into areas where they may not be genetically adaptable.
So their environment shifts at each time change and note that there are two axis and it shifts up to the
upper right. The only ones that can survive in this new environment is the genotype with that
particular configuration so you lose all the other genetic variation. So if you think of glaciation and
deglaciation this continuous back and forth had to result in a lot of loss of genetic variation.
Types of things that might change – we expect populations to go north and south of the equator but
what changes might happen to which they have to adapt to? The critical thing that changes is light.
Equator you have 12:12 hours (light/dark). So how do 1 million Wildebeest get together to breed
within 5 days? By the moon. If you go into the woods right now the white tailed deer males will be
breeding. I had a student walking out to my research trailer and a buck (male deer) chased him. It hit
the door of the trailer. All they think about are females right now. They are synchronized to this
latitude and the time giver is light. They know the light is decreasing and they know to shift the
BGYC58H3F.October,30, 2007 LECTURE 7 2